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Einstein's theory of special relativity

Why you can't travel at the speed of light

A lbert Einstein is famous for many things, not least his theories of relativity. The first, the special theory of relativity, was the one that began the physicist's reputation for tearing apart the classical worldview that had come before. Special relativity, a way of relating the motion of objects in the universe, led scientists to re-evaluate their assumptions about things as fundamental as time and space. And it led to important revelations about the relationship between energy and matter.

Special relativity was published by Einstein in 1905, in a paper titled "On the Electrodynamics of Moving Bodies". He came to it after picking on a conflict he noticed between the equations for electricity and magnetism, which the physicist James Clerk Maxwell had recently developed, and Isaac Newton's more established laws of motion.

Light, according to Maxwell, was a vibration in the electromagnetic field and it travelled at a constant speed in a vacuum. More than 100 years earlier, Newton had set down his laws of motion and, together with ideas from Galileo Galilei, these showed how the speed of an object would differ depend on who was measuring it and how they were moving relative to the object. A ball you are holding will seem still to you, even when you're in a moving car. But that ball will seem to be moving to anyone standing on the pavement.

But there was a problem in applying Newton's laws of motion to light. In Maxwell's equations, the speed of electromagnetic waves is a constant defined by the properties of the material through which the waves move. There is nothing in there that allows the speed of these waves to be different for different people depending on how they were moving relative to each other. Which is bizarre, if you think about it.

Imagine someone sitting in a stationary train, throwing a ball from where he's sitting to the opposite wall, a few metres further down the train from him. You, standing on the station platform, measure the speed of the ball at the same value as the person on the train.

Now the train starts to move (in the direction of the ball), and you again measure the speed of the ball. You would rightly calculate it as higher – the initial speed (ie, when the train was at rest) plus the forward speed of the train. On the train, meanwhile, the game-player will notice nothing different. Your two values for the speed of the ball will be different; both correct for your frames of reference.

Replace the ball with light and this calculation goes awry. If the person on the train were shining a light at the opposite wall and measured the speed of the particles of light (photons), you and the passenger would both find that the photons had the same speed at all times. In all cases, the speed of the photons would stay at just under 300,000 kilometres per second, as Maxwell's equations say they should.

Einstein took this idea – the invariance of the speed of light – as one of his two postulates for the special theory of relativity. The other postulate was that the laws of physics are the same wherever you are, whether on an plane or standing on a country road. But to keep the speed of light constant at all times and for all observers, in special relativity, space and time become stretchy and variable. Time is not absolute, for example. A moving clock ticks more slowly than a stationary one. Travel at the speed of light and, theoretically, the clock would stop altogether.

How much the time dilates can be calculated by the two equations above. On the right, Δt is the time interval between two events as measured by the person they affect. (In our example above, this would be the person in the train.) On the left, Δt' is the time interval between the same two events but measured by an outside observer in a separate frame of reference (the person on the platform). These two times are related by the Lorentz factor (γ), which in this example is a term that takes into account the velocity (v) of the train relative to the station platform, which is "at rest". In this expression, c is a constant equal to the speed of light in a vacuum.

The length of moving objects also shrink in the direction in which they move. Get to the speed of light (not really possible, but imagine if you could for a moment) and the object's length would shrink to zero.

The contracted length of a moving object relative to a stationary one can be calculated by dividing the proper length by the Lorentz factor – if it were possible for an object to reach the speed of light its length would shrink to zero.

It is important to note that if you were the person moving faster and faster, you would not notice anything: time would tick normally for you and you would not be squashed in length. But anyone watching you from the celestial station platform would be able to measure the differences, as calculated from the Lorentz factor. However, for everyday objects and everyday speeds, the Lorentz factor will be close to 1 – it is only at speeds close to that of light that the relativistic effects need serious attention.

Another feature that emerges from special relativity is that, as something speeds up, its mass increases compared with its mass at rest, with the mass of the moving object determined by multiplying its rest mass by the Lorentz factor. This increase in relativistic mass makes every extra unit of energy you put into speeding up the object less effective at making it actually move faster.

As the speed of the object increases and starts to reach appreciable fractions of the speed of light (c), the portion of energy going into making the object more massive gets bigger and bigger.

This explains why nothing can travel faster than light – at or near light speed, any extra energy you put into an object does not make it move faster but just increases its mass. Mass and energy are the same thing – this is a profoundly important result. But that is another story.

  • Albert Einstein
  • A short history of equations
  • Isaac Newton

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Here's What Actually Happens When You Travel at the Speed of Light, According to NASA

NASA created a fun video to answer all of our burning questions about near-light-speed travel.

will travel at the speed of light ever be possible

Ever wish you could travel at the speed of light to your favorite destinations ? Once you see the reality of that speed, you may rethink everything.

"There are some important things you should probably know about approaching the speed of light," NASA's video, Guide to Near-light-speed Travel , explains. "First, a lot of weird things can happen, like time and space getting all bent out of shape."

According to the video, if you're traveling at nearly the speed of light, the clock inside your rocket would show it takes less time to travel to your destination than it would on Earth. But, since the clocks at home would be moving at a standard rate you'd return home to everyone else being quite a bit older.

"Also, because you're going so fast, what would otherwise be just a few hydrogen atoms that you'd run into quickly becomes a lot of dangerous particles. So you should probably have shields that keep them from frying your ship and also you."

Finally, the video tackles the fact that even if you were moving at the speed of light, the "universe is also a very big place, so you might be in for some surprises." For example, your rocket's clock will say it takes about nine months to get from Earth to the edge of the solar system. An Earth clock would say it took about a year and a half. Fortunately, NASA astronauts have a slew of tips for avoiding jet lag along the way.

"If you want to get to farther out vacation spots," the video explains, "you'll probably need more than a few extra snacks. A trip to the Andromeda Galaxy, our nearest large neighbor galaxy, can take over one million years. And a trip to the farthest known galaxy where it currently sits might take over 15 billion years, which is more vacation time than I think I'll ever have."

The video doesn't explain how your rocket will travel at the speed of light. Our technology just isn't there yet, but maybe the aliens will share that tech with us soon. Until then, you can track the first crew launch of Artemis II , a rocket that will fly around the moon in 2024 before making its first lunar landing in 2025.

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Is time travel possible? An astrophysicist explains

Time travel is one of the most intriguing topics in science.

Will it ever be possible for time travel to occur? – Alana C., age 12, Queens, New York

Have you ever dreamed of traveling through time, like characters do in science fiction movies? For centuries, the concept of time travel has captivated people’s imaginations. Time travel is the concept of moving between different points in time, just like you move between different places. In movies, you might have seen characters using special machines, magical devices or even hopping into a futuristic car to travel backward or forward in time.

But is this just a fun idea for movies, or could it really happen?

The question of whether time is reversible remains one of the biggest unresolved questions in science. If the universe follows the  laws of thermodynamics , it may not be possible. The second law of thermodynamics states that things in the universe can either remain the same or become more disordered over time.

It’s a bit like saying you can’t unscramble eggs once they’ve been cooked. According to this law, the universe can never go back exactly to how it was before. Time can only go forward, like a one-way street.

Time is relative

However, physicist Albert Einstein’s  theory of special relativity  suggests that time passes at different rates for different people. Someone speeding along on a spaceship moving close to the  speed of light  – 671 million miles per hour! – will experience time slower than a person on Earth.

Related: The speed of light, explained

People have yet to build spaceships that can move at speeds anywhere near as fast as light, but astronauts who visit the International Space Station orbit around the Earth at speeds close to 17,500 mph. Astronaut Scott Kelly has spent 520 days at the International Space Station, and as a result has aged a little more slowly than his twin brother – and fellow astronaut – Mark Kelly. Scott used to be 6 minutes younger than his twin brother. Now, because Scott was traveling so much faster than Mark and for so many days, he is  6 minutes and 5 milliseconds younger .

Some scientists are exploring other ideas that could theoretically allow time travel. One concept involves  wormholes , or hypothetical tunnels in space that could create shortcuts for journeys across the universe. If someone could build a wormhole and then figure out a way to move one end at close to the speed of light – like the hypothetical spaceship mentioned above – the moving end would age more slowly than the stationary end. Someone who entered the moving end and exited the wormhole through the stationary end would come out in their past.

However, wormholes remain theoretical : Scientists have yet to spot one. It also looks like it would be  incredibly challenging  to send humans through a wormhole space tunnel.

Time travel paradoxes and failed dinner parties

There are also paradoxes associated with time travel. The famous “ grandfather paradox ” is a hypothetical problem that could arise if someone traveled back in time and accidentally prevented their grandparents from meeting. This would create a paradox where you were never born, which raises the question: How could you have traveled back in time in the first place? It’s a mind-boggling puzzle that adds to the mystery of time travel.

Famously, physicist Stephen Hawking tested the possibility of time travel by  throwing a dinner party  where invitations noting the date, time and coordinates were not sent out until after it had happened. His hope was that his invitation would be read by someone living in the future, who had capabilities to travel back in time. But no one showed up.

As he  pointed out : “The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.”

Telescopes are time machines

Interestingly, astrophysicists armed with powerful telescopes possess a unique form of time travel. As they peer into the vast expanse of the cosmos, they gaze into the past universe. Light from all galaxies and stars takes time to travel, and these beams of light carry information from the distant past. When astrophysicists observe a star or a galaxy through a telescope, they are not seeing it as it is in the present, but as it existed when the light began its journey to Earth millions to billions of years ago.

NASA’s newest space telescope, the  James Webb Space Telescope , is peering at galaxies that were formed at the very beginning of the Big Bang, about 13.7 billion years ago.

While we aren’t likely to have time machines like the ones in movies anytime soon, scientists are actively researching and exploring new ideas. But for now, we’ll have to enjoy the idea of time travel in our favorite books, movies and dreams.

This article first appeared on the Conversation. You can read the original here .

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to  [email protected] . Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

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This Trick Flips Space and Time

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By Meddling With Spacetime Dimensions, We Could Finally Reach Warp Speed

New research shows that the “superluminal observer” needs three separate time dimensions for a warp-speed math trick that would please even Galileo.

✅ Quick Facts:

  • In new research, the lead scientist explains why just one space and one time aren’t enough for this scenario.
  • Symmetry is a physics concept that goes all the way back to Galileo’s time.

The secret to faster-than-light physics could be to double down on the number of dimensions. Specifically, the solution may lie in three dimensions of time , with just one representing space. The math is deep and complicated, but the ideas may be within our grasp after all. And there’s one math trick at superspeeds that may just “flip” your lid.

The key idea at play is that of a “superluminal observer,” according to research published in December 2022 in the journal Classical and Quantum Gravity. “Superluminal” means faster than light, from super - meaning “more” or “most,” and - luminal like, well, Lumière from Beauty and the Beast, and the lumens that power your home movie projector. The superluminal observer is a hypothetical thing that is looking at the universe while traveling faster than light. It’s you in your Star Trek warp-speed shuttle.

star trek

Superluminal observers are cool because, in a way, they marry together two very different sides of physics: general relativity and quantum mechanics . General relativity is the work embodied by Albert Einstein, which governs how spacetime functions as bodies move around the universe at subluminal, or slower than light, speeds. Quantum mechanics explains how subatomic particles behave, or don’t behave, in very strange ways on the smallest of scales.

The research team—led by theoretical physicist Andrzej Dragan of the University of Warsaw and the National University of Singapore—has theorized that many parts of quantum physics, like indeterminism and superposition , can be explained if you take general relativity and apply its principles to the superluminal observer. In other words, how messy does spacetime get if we take our shuttle up to warp speed? Is everything suddenly in multiple places at once?

Dragan’s new work indicates that it’s at least a possibility. Perhaps more interestingly, the way general relativity becomes quantum phenomena at speeds greater than light doesn’t seem to introduce any causal paradoxes. In earlier work , published in the New Journal of Physics in March 2020, Dragan and his coauthor studied “just” one space dimension and one time dimension, known as 1+1. In the new paper, the researchers upped the ante to include one space dimension and three time dimensions, or 1+3.

When Time and Space Flip Math

Why do we need three time dimensions? To understand, we have to talk about some math. “[D]espite our common perception, time and space are strikingly similar according to relativity, and mathematically the only difference between them is the minus sign somewhere in the equations,” Dragan explains to Popular Mechanics in an email. That’s a small difference in complicated math, but think of the algebra example of the difference of two squares: x² - 16, for example, is the result of (x - 4)(x + 4). With one flipped sign, the middle term in the polynomial falls away.

But when the observer is going faster than the speed of light, the difference in signs also changes. That’s because time and space must flip in the math. “The time of the superluminal observer becomes space of the subluminal one, and their space becomes time,” Dragan says. In other words, the regular, non-light-speed observer’s space and time turn into the time and space, relatively, of the faster-than-light observer. “So their corresponding signs have to interchange.”

In a 1+1 scenario, that means the two dimensions are the same, making it redundant. If 50 = 50, does it matter which 50 is which? (In logic, we call this a tautology.) That means that if we want to truly study space and time as different things, we have to add a second “set” of two dimensions: space and time 1, together, represent space; while time 2 and time 3, together, represent time . It’s not quite the difference of two squares, but we have two balanced sets of dimensions.

The Symmetry in Physics

balls balancing on scale

There’s another interesting aspect to this research, because Dragan’s team wants to show that even at superluminal speeds, physics shows symmetry.

“The idea of symmetry in physics can be traced back to Galileo,” Dragan says. “He noticed that no matter what velocity we move at, as long as that velocity is constant, our physics remains the same. A parrot flying in a moving ship experiences the same dynamical laws as at ‘rest’ on Earth.”

✅ Galileo Galilei was an influential Italian scientist who lived during the 16th and 17th centuries. As an elderly man, he received a life sentence for going public with his belief that Earth orbited the sun!

But our conceptions of physics are limited by the long-running (and reasonable!) belief that nothing can travel faster than light, Dragan explains. That means the superluminal observer, by definition, exists as a kind of exception into which we must work to extend the idea of symmetry. Does it make sense that a superluminal observer would still be subject to symmetry? Is the parrot traveling faster than light still the same as the parrot in the ship or on Earth?

“We argued that this additional limiting assumption isn’t necessary,” Dragan says. He believes symmetry may extend into faster-than-light speeds, and our parrot friend would be just as affected by the same laws of physics while traveling in the warp-speed shuttle.

Toward a Grand Unified Theory

So, this paper isn’t about traveling at warp speed, but instead an analysis of physics to show how we can bring two very different physics branches together. Why is that, itself, so important?

“The idea of more than one time dimension has been considered by others over the years, so that particular premise is not novel,” Harold “Sonny” White, a onetime NASA physicist and the founder of the Limitless Space Institute (LSI), a group that funds and promotes far-out space travel and physics research, tells Popular Mechanics . “But the mathematical framework developed by the authors in this published paper is unique. It would seem the authors’ perceived benefit from the effort is that it establishes a mathematical basis for why we need a field theoretical framework.”

einstein writing equation on blackboard

What is a field theoretical framework? It’s the big picture of physics that can bring everything together. “[I]f we envision the standard models of physics as a Venn diagram, there would be two circles side-by-side that touch at a single tangent point,” White explains. “The idea of a grand unified field theory might be envisioned as a larger circle that encircles both the smaller circles.”

By showing their work, these researchers have pointed out a really specific way in which one big basket of physics—rather than two baskets that we aren’t sure how to carry at the same time—would make more sense in practical and mathematical terms.

Okay, sure, you may be thinking: all this superluminal jabberwocky is interesting. But warp speed itself is science fiction, right? (At least for now: White’s LSI funds education that may eventually lead us elsewhere.) The superluminal observer is just a thought exercise ... right?

Dragan isn’t so sure. “The last remaining question is whether superluminal objects are only a mathematical possibility, or they actually exist in reality,” he concludes. “We believe the latter to be that case, and that is the purpose of our further research.”

That means our warp-speed shuttle, once the most far-out thing science fiction writers could even imagine, could embody an elegant theory that brings together two very different kinds of physics. Indeed, objects in the superluminal mirror may be closer than they appear.

Headshot of Caroline Delbert

Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all. 

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Can anything travel faster than the speed of light?

Does it matter if it's in a vacuum?

Artist's impression of beams of light

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch mathematician and scientist Christiaan Huygens became the first person to attempt to determine the actual speed of light, according to the American Museum of Natural History in New York City. Huygens came up with a figure of 131,000 miles per second (211,000 kilometers per second), a number that isn't accurate by today's standards — we now know that the speed of light in the "vacuum" of empty space is about 186,282 miles per second (299,792 km per second) — but his assessment showcased that light travels at an incredible speed.

According to Albert Einstein 's theory of special relativity , light travels so fast that, in a vacuum, nothing in the universe is capable of moving faster. 

"We cannot move through the vacuum of space faster than the speed of light," confirmed Jason Cassibry, an associate professor of aerospace engineering at the Propulsion Research Center, University of Alabama in Huntsville.

Question answered, right? Maybe not. When light is not in a vacuum, does the rule still apply?

Related: How many atoms are in the observable universe?

"Technically, the statement 'nothing can travel faster than the speed of light' isn't quite correct by itself," at least in a non-vacuum setting, Claudia de Rham, a theoretical physicist at Imperial College London, told Live Science in an email. But there are certain caveats to consider, she said. Light exhibits both particle-like and wave-like characteristics, and can therefore be regarded as both a particle (a photon ) and a wave. This is known as wave-particle duality.

If we look at light as a wave, then there are "multiple reasons" why certain waves can travel faster than white (or colorless) light in a medium, de Rham said. One such reason, she said, is that "as light travels through a medium — for instance, glass or water droplets — the different frequencies or colors of light travel at different speeds." The most obvious visual example of this occurs in rainbows, which typically have the long, faster red wavelengths at the top and the short, slower violet wavelengths at the bottom, according to a post by the University of Wisconsin-Madison . 

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When light travels through a vacuum, however, the same is not true. "All light is a type of electromagnetic wave, and they all have the same speed in a vacuum (3 x 10^8 meters per second). This means both radio waves and gamma rays have the same speed," Rhett Allain, a physics professor at Southeastern Louisiana University, told Live Science in an email.

So, according to de Rham, the only thing capable of traveling faster than the speed of light is, somewhat paradoxically, light itself, though only when not in the vacuum of space. Of note, regardless of the medium, light will never exceed its maximum speed of 186,282 miles per second.

Universal look

According to Cassibry, however, there is something else to consider when discussing things moving faster than the speed of light.

"There are parts of the universe that are expanding away from us faster than the speed of light, because space-time is expanding," he said. For example, the Hubble Space Telescope recently spotted 12.9 billion year-old light from a distant star known as Earendel. But, because the universe is expanding at every point, Earendel is moving away from Earth and has been since its formation, so the galaxy is now 28 billion light years away from Earth.

In this case, space-time is expanding, but the material in space-time is still traveling within the bounds of light speed.

Related: Why is space a vacuum?

Diagram of the visible color spectrum

So, it's clear that nothing travels faster than light that we know of, but is there any situation where it might be possible? Einstein's theory of special relativity, and his subsequent theory of general relativity, is "built under the principle that the notions of space and time are relative," de Rham said. But what does this mean? "If someone [were] able to travel faster than light and carry information with them, their notion of time would be twisted as compared to ours," de Rham said. "There could be situations where the future could affect our past, and then the whole structure of reality would stop making sense."

This would indicate that it would probably not be desirable to make a human travel faster than the speed of light. But could it ever be possible? Will there ever be a time when we are capable of creating craft that could propel materials — and ultimately humans — through space at a pace that outstrips light speed? "Theorists have proposed various types of warp bubbles that could enable faster-than-light travel," Cassibry said.

But is de Rham convinced?

"We can imagine being able to communicate at the speed of light with systems outside our solar system ," de Rham said. "But sending actual physical humans at the speed of light is simply impossible, because we cannot accelerate ourselves to such speed.

"Even in a very idealistic situation where we imagine we could keep accelerating ourselves at a constant rate — ignoring how we could even reach a technology that could keep accelerating us continuously — we would never actually reach the speed of light," she added. "We could get close, but never quite reach it."

Related: How long is a galactic year?

This is a point confirmed by Cassibry. "Neglecting relativity, if you were to accelerate with a rate of 1G [Earth gravity], it would take you a year to reach the speed of light. However, you would never really reach that velocity because as you start to approach lightspeed, your mass energy increases, approaching infinite. "One of the few known possible 'cheat codes' for this limitation is to expand and contract spacetime, thereby pulling your destination closer to you. There seems to be no fundamental limit on the rate at which spacetime can expand or contract, meaning we might be able to get around this velocity limit someday."

— What would happen if the speed of light were much lower?

— What if the speed of sound were as fast as the speed of light?

— How does the rubber pencil illusion work?

Allain is similarly confident that going faster than light is far from likely, but, like Cassibry, noted that if humans want to explore distant planets, it may not actually be necessary to reach such speeds. "The only way we could understand going faster than light would be to use some type of wormhole in space," Allain said. "This wouldn't actually make us go faster than light, but instead give us a shortcut to some other location in space."

Cassibry, however, is unsure if wormholes will ever be a realistic option.

"Wormholes are theorized to be possible based on a special solution to Einstein's field equations," he said. "Basically, wormholes, if possible, would give you a shortcut from one destination to another. I have no idea if it's possible to construct one, or how we would even go about doing it." Originally published on Live Science.

Joe Phelan

Joe Phelan is a journalist based in London. His work has appeared in VICE, National Geographic, World Soccer and The Blizzard, and has been a guest on Times Radio. He is drawn to the weird, wonderful and under examined, as well as anything related to life in the Arctic Circle. He holds a bachelor's degree in journalism from the University of Chester. 

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will travel at the speed of light ever be possible

Expert Voices

Is Interstellar Travel Really Possible?

Interstellar flight is a real pain in the neck.

Artist’s illustration of a Breakthrough Starshot probe arriving at the potentially Earth-like planet Proxima Centauri b. A representation of laser beams is visible emanating from the corners of the craft’s lightsail.

Paul M. Sutter is an astrophysicist at The Ohio State University , host of Ask a Spaceman and Space Radio , and author of " Your Place in the Universe. " Sutter contributed this article to Space.com's Expert Voices: Op-Ed & Insights . 

Interstellar space travel . Fantasy of every five-year-old kid within us. Staple of science fiction serials. Boldly going where nobody has gone before in a really fantastic way. As we grow ever more advanced with our rockets and space probes, the question arises: could we ever hope to colonize the stars? Or, barring that far-flung dream, can we at least send space probes to alien planets, letting them tell us what they see?

The truth is that interstellar travel and exploration is technically possible . There's no law of physics that outright forbids it. But that doesn't necessarily make it easy, and it certainly doesn't mean we'll achieve it in our lifetimes, let alone this century. Interstellar space travel is a real pain in the neck. 

Related: Gallery: Visions of Interstellar Starship Travel

Voyage outward

If you're sufficiently patient, then we've already achieved interstellar exploration status. We have several spacecraft on escape trajectories, meaning they're leaving the solar system and they are never coming back. NASA's Pioneer missions, the Voyager missions , and most recently New Horizons have all started their long outward journeys. The Voyagers especially are now considered outside the solar system, as defined as the region where the solar wind emanating from the sun gives way to general galactic background particles and dust.

So, great; we have interstellar space probes currently in operation. Except the problem is that they're going nowhere really fast. Each one of these intrepid interstellar explorers is traveling at tens of thousands of miles per hour, which sounds pretty fast. They're not headed in the direction of any particular star, because their missions were designed to explore planets inside the solar system. But if any of these spacecraft were headed to our nearest neighbor, Proxima Centauri , just barely 4 light-years away, they would reach it in about 80,000 years.

I don't know about you, but I don't think NASA budgets for those kinds of timelines. Also, by the time these probes reach anywhere halfway interesting, their nuclear batteries will be long dead, and just be useless hunks of metal hurtling through the void. Which is a sort of success, if you think about it: It's not like our ancestors were able to accomplish such feats as tossing random junk between the stars, but it's probably also not exactly what you imagined interstellar space travel to be like.

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Related: Superfast Spacecraft Propulsion Concepts (Images)

Speed racer

To make interstellar spaceflight more reasonable, a probe has to go really fast. On the order of at least one-tenth the speed of light. At that speed, spacecraft could reach Proxima Centauri in a handful of decades, and send back pictures a few years later, well within a human lifetime. Is it really so unreasonable to ask that the same person who starts the mission gets to finish it?

Going these speeds requires a tremendous amount of energy. One option is to contain that energy onboard the spacecraft as fuel. But if that's the case, the extra fuel adds mass, which makes it even harder to propel it up to those speeds. There are designs and sketches for nuclear-powered spacecraft that try to accomplish just this, but unless we want to start building thousands upon thousands of nuclear bombs just to put inside a rocket, we need to come up with other ideas.

Perhaps one of the most promising ideas is to keep the energy source of the spacecraft fixed and somehow transport that energy to the spacecraft as it travels. One way to do this is with lasers. Radiation is good at transporting energy from one place to another, especially over the vast distances of space. The spacecraft can then capture this energy and propel itself forward.

This is the basic idea behind the Breakthrough Starshot project , which aims to design a spacecraft capable of reaching the nearest stars in a matter of decades. In the simplest outline of this project, a giant laser on the order of 100 gigawatts shoots at an Earth-orbiting spacecraft. That spacecraft has a large solar sail that is incredibly reflective. The laser bounces off of that sail, giving momentum to the spacecraft. The thing is, a 100-gigawatt laser only has the force of a heavy backpack. You didn't read that incorrectly. If we were to shoot this laser at the spacecraft for about 10 minutes, in order to reach one-tenth the speed of light, the spacecraft can weigh no more than a gram.

That's the mass of a paper clip.

Related: Breakthrough Starshot in Pictures: Laser-Sailing Nanocraft to Study Alien Planets

A spaceship for ants

This is where the rubber meets the interstellar road when it comes to making spacecraft travel the required speeds. The laser itself, at 100 gigawatts, is more powerful than any laser we've ever designed by many orders of magnitude. To give you a sense of scale, 100 gigawatts is the entire capacity of every single nuclear power plant operating in the United States combined.

And the spacecraft, which has to have a mass no more than a paper clip, must include a camera, computer, power source, circuitry, a shell, an antenna for communicating back home and the entire lightsail itself.  

That lightsail must be almost perfectly reflective. If it absorbs even a tiny fraction of that incoming laser radiation it will convert that energy to heat instead of momentum. At 100 gigawatts, that means straight-up melting, which is generally considered not good for spacecraft. 

Once accelerated to one-tenth the speed of light, the real journey begins. For 40 years, this little spacecraft will have to withstand the trials and travails of interstellar space. It will be impacted by dust grains at that enormous velocity. And while the dust is very tiny, at those speeds motes can do incredible damage. Cosmic rays, which are high-energy particles emitted by everything from the sun to distant supernova, can mess with the delicate circuitry inside. The spacecraft will be bombarded by these cosmic rays non-stop as soon as the journey begins.

Is Breakthrough Starshot possible? In principle, yes. Like I said above, there's no law of physics that prevents any of this from becoming reality. But that doesn't make it easy or even probable or plausible or even feasible using our current levels of technology (or reasonable projections into the near future of our technology). Can we really make a spacecraft that small and light? Can we really make a laser that powerful? Can a mission like this actually survive the challenges of deep space?

The answer isn't yes or no. The real question is this: are we willing to spend enough money to find out if it's possible?

  • Building Sails for Tiny Interstellar Probes Will Be Tough — But Not Impossible
  • 10 Exoplanets That Could Host Alien Life
  • Interstellar Space Travel: 7 Futuristic Spacecraft to Explore the Cosmos

Learn more by listening to the episode "Is interstellar travel possible?" on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com . Thanks to @infirmus, Amber D., neo, and Alex V. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter .  

Follow us on Twitter @Spacedotcom or Facebook . 

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Paul Sutter

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York City. Paul received his PhD in Physics from the University of Illinois at Urbana-Champaign in 2011, and spent three years at the Paris Institute of Astrophysics, followed by a research fellowship in Trieste, Italy, His research focuses on many diverse topics, from the emptiest regions of the universe to the earliest moments of the Big Bang to the hunt for the first stars. As an "Agent to the Stars," Paul has passionately engaged the public in science outreach for several years. He is the host of the popular "Ask a Spaceman!" podcast, author of "Your Place in the Universe" and "How to Die in Space" and he frequently appears on TV — including on The Weather Channel, for which he serves as Official Space Specialist.

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will travel at the speed of light ever be possible

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Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

Image of galaxies, taken by the Hubble Space Telescope.

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

Illustration of GPS satellites orbiting around Earth

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

Illustration of a hand holding a phone with a maps application active.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

If you liked this, you may like:

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Could a telescope ever see the beginning of time? An astronomer explains

will travel at the speed of light ever be possible

Assistant Professor of Astronomy and Astrophysics, University of Maryland, Baltimore County

Disclosure statement

Adi Foord does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

University of Maryland, Baltimore County provides funding as a member of The Conversation US.

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will travel at the speed of light ever be possible

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] .

If the James Webb telescope was 10 times more powerful, could we see the beginning of time? - Sam H., age 12, Prosper, Texas

The James Webb Space Telescope, or JWST for short, is one of the most advanced telescopes ever built . Planning for JWST began over 25 years ago, and construction efforts spanned over a decade. It was launched into space on Dec. 25, 2021, and within a month arrived at its final destination: 930,000 miles away from Earth. Its location in space allows it a relatively unobstructed view of the universe .

The telescope design was a global effort , led by NASA, and intended to push the boundaries of astronomical observation with revolutionary engineering. Its mirror is massive – about 21 feet (6.5 meters) in diameter. That’s nearly three times the size of the Hubble Space Telescope, which launched in 1990 and is still working today.

It’s a telescope’s mirror that allows it to collect light. JWST’s is so big that it can “see” the faintest and farthest galaxies and stars in the universe. Its state-of-the-art instruments can reveal information about the composition, temperature and motion of these distant cosmic objects.

As an astrophysicist , I’m continually looking back in time to see what stars, galaxies and supermassive black holes looked like when their light began its journey toward Earth, and I’m using that information to better understand their growth and evolution. For me, and for thousands of space scientists, the James Webb Space Telescope is a window to that unknown universe.

Just how far back can JWST peer into the cosmos and into the past? About 13.5 billion years.

Against the blackness of space, the golden mirrors of the telescope are prominent.

Time travel

A telescope does not show stars, galaxies and exoplanets as they are right now. Instead, astronomers are catching a glimpse of how they were in the past . It takes time for light to travel across space and reach our telescopes. In essence, that means a look into space is also a trip back in time.

This is even true for objects that are quite close to us. The light you see from the Sun left it about 8 minutes, 20 seconds earlier. That’s how long it takes for the Sun’s light to travel to Earth .

You can easily do the math on this. All light – whether sunlight, a flashlight or a light bulb in your house – travels at 186,000 miles (almost 300,000 kilometers) per second . That’s just over 11 million miles (about 18 million kilometers) per minute. The Sun is about 93 million miles (150 million kilometers) from Earth. That comes out to about 8 minutes, 20 seconds.

But the farther away something is, the longer its light takes to reach us. That’s why the light we see from Proxima Centauri , the closest star to us aside from our Sun, is 4 years old; that is, it’s about 25 trillion miles (approximately 40 trillion kilometers) away from Earth, so that light takes just over four years to reach us. Or, as scientists like to say, four light years .

Most recently, JWST observed Earendel, one of the farthest stars ever detected . The light that JWST sees from Earendel is about 12.9 billion years old.

The James Webb Space Telescope is looking much farther back in time than previously possible with other telescopes, such as the Hubble Space Telescope . For example, although Hubble can see objects 60,000 times fainter than the human eye is able, the JWST can see objects almost nine times fainter than even Hubble can .

A diagram that shows how far back the James Webb Space Telescope can see.

The Big Bang

But is it possible to see back to the beginning of time?

The Big Bang is a term used to define the beginning of our universe as we know it. Scientists believe it occurred about 13.8 billion years ago . It is the most widely accepted theory among physicists to explain the history of our universe.

The name is a bit misleading, however, because it suggests that some sort of explosion, like fireworks, created the universe. The Big Bang more closely represents the appearance of rapidly expanding space everywhere in the universe. The environment immediately after the Big Bang was similar to a cosmic fog that covered the universe, making it hard for light to travel beyond it. Eventually, galaxies, stars and planets started to grow.

That’s why this era in the universe is called the “cosmic dark ages.” As the universe continued to expand, the cosmic fog began to rise , and light was eventually able to travel freely through space. In fact, a few satellites have observed the light left by the Big Bang, about 380,000 years after it occurred. These telescopes were built to detect the splotchy leftover glow from the Big Bang , whose light can be tracked in the microwave band.

However, even 380,000 years after the Big Bang, there were no stars and galaxies. The universe was still a very dark place. The cosmic dark ages wouldn’t end until a few hundred million years later, when the first stars and galaxies began to form.

Clouds of red, pink and white gas and dust highlight this starscape.

The James Webb Space Telescope was not designed to observe as far back as the Big Bang, but instead to see the period when the first objects in the universe began to form and emit light. Before this time period, there is little light for the James Webb Space Telescope to observe, given the conditions of the early universe and the lack of galaxies and stars.

Peering back to the time period close to the Big Bang is not simply a matter of having a larger mirror – astronomers have already done it using other satellites that observe microwave emission from very soon after the Big Bang . So, the James Webb Space Telescope observing the universe a few hundred million years after the Big Bang isn’t a limitation of the telescope. Rather, that’s actually the telescope’s mission. It’s a reflection of where in the universe we expect the first light from stars and galaxies to emerge.

By studying ancient galaxies, scientists hope to understand the unique conditions of the early universe and gain insight into the processes that helped them flourish. That includes the evolution of supermassive black holes, the life cycle of stars, and what exoplanets – worlds beyond our solar system – are made of.

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Could A Telescope Ever See The Beginning Of Time?

file-20240312-26-olxvyb

The James Webb Space Telescope, or JWST for short, is one of the most advanced telescopes ever built . Planning for JWST began over 25 years ago, and construction efforts spanned over a decade. It was launched into space on Dec. 25, 2021, and within a month arrived at its final destination: 930,000 miles away from Earth. Its location in space allows it a relatively unobstructed view of the universe .

The telescope design was a global effort , led by NASA, and intended to push the boundaries of astronomical observation with revolutionary engineering. Its mirror is massive – about 21 feet (6.5 meters) in diameter. That’s nearly three times the size of the Hubble Space Telescope, which launched in 1990 and is still working today.

It’s a telescope’s mirror that allows it to collect light. JWST’s is so big that it can “see” the faintest and farthest galaxies and stars in the universe. Its state-of-the-art instruments can reveal information about the composition, temperature and motion of these distant cosmic objects.

As an astrophysicist , I’m continually looking back in time to see what stars, galaxies and supermassive black holes looked like when their light began its journey toward Earth, and I’m using that information to better understand their growth and evolution. For me, and for thousands of space scientists, the James Webb Space Telescope is a window to that unknown universe.

Just how far back can JWST peer into the cosmos and into the past? About 13.5 billion years.

Time Travel

A telescope does not show stars, galaxies and exoplanets as they are right now. Instead, astronomers are catching a glimpse of how they were in the past . It takes time for light to travel across space and reach our telescopes. In essence, that means a look into space is also a trip back in time.

This is even true for objects that are quite close to us. The light you see from the Sun left it about 8 minutes, 20 seconds earlier. That’s how long it takes for the Sun’s light to travel to Earth .

You can easily do the math on this. All light – whether sunlight, a flashlight or a light bulb in your house – travels at 186,000 miles (almost 300,000 kilometers) per second . That’s just over 11 million miles (about 18 million kilometers) per minute. The Sun is about 93 million miles (150 million kilometers) from Earth. That comes out to about 8 minutes, 20 seconds.

But the farther away something is, the longer its light takes to reach us. That’s why the light we see from Proxima Centauri , the closest star to us aside from our Sun, is 4 years old; that is, it’s about 25 trillion miles (approximately 40 trillion kilometers) away from Earth, so that light takes just over four years to reach us. Or, as scientists like to say, four light years .

Most recently, JWST observed Earendel, one of the farthest stars ever detected . The light that JWST sees from Earendel is about 12.9 billion years old.

The James Webb Space Telescope is looking much farther back in time than previously possible with other telescopes, such as the Hubble Space Telescope . For example, although Hubble can see objects 60,000 times fainter than the human eye is able, the JWST can see objects almost nine times fainter than even Hubble can .

The Big Bang

But is it possible to see back to the beginning of time?

The Big Bang is a term used to define the beginning of our universe as we know it. Scientists believe it occurred about 13.8 billion years ago . It is the most widely accepted theory among physicists to explain the history of our universe.

The name is a bit misleading, however, because it suggests that some sort of explosion, like fireworks, created the universe. The Big Bang more closely represents the appearance of rapidly expanding space everywhere in the universe. The environment immediately after the Big Bang was similar to a cosmic fog that covered the universe, making it hard for light to travel beyond it. Eventually, galaxies, stars and planets started to grow.

That’s why this era in the universe is called the “cosmic dark ages.” As the universe continued to expand, the cosmic fog began to rise , and light was eventually able to travel freely through space. In fact, a few satellites have observed the light left by the Big Bang, about 380,000 years after it occurred. These telescopes were built to detect the splotchy leftover glow from the Big Bang , whose light can be tracked in the microwave band.

However, even 380,000 years after the Big Bang, there were no stars and galaxies. The universe was still a very dark place. The cosmic dark ages wouldn’t end until a few hundred million years later, when the first stars and galaxies began to form.

The James Webb Space Telescope was not designed to observe as far back as the Big Bang, but instead to see the period when the first objects in the universe began to form and emit light. Before this time period, there is little light for the James Webb Space Telescope to observe, given the conditions of the early universe and the lack of galaxies and stars.

Peering back to the time period close to the Big Bang is not simply a matter of having a larger mirror – astronomers have already done it using other satellites that observe microwave emission from very soon after the Big Bang . So, the James Webb Space Telescope observing the universe a few hundred million years after the Big Bang isn’t a limitation of the telescope. Rather, that’s actually the telescope’s mission. It’s a reflection of where in the universe we expect the first light from stars and galaxies to emerge.

By studying ancient galaxies, scientists hope to understand the unique conditions of the early universe and gain insight into the processes that helped them flourish. That includes the evolution of supermassive black holes, the life cycle of stars, and what exoplanets – worlds beyond our solar system – are made of.

Adi Foord is an Assistant Professor of Astronomy and Astrophysics at the University of Maryland, Baltimore County. This article is republished from The Conversation under a Creative Commons license . Read the original article .

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Politics latest: 'Big questions' for Sunak over claims against suspended Tory MP; Sturgeon's husband charged over alleged embezzlement

Labour's chairwoman says there are "big questions" for Rishi Sunak over allegations against Tory MP Mark Menzies, who has been suspended by the party. Meanwhile, Nicola Sturgeon's husband, Peter Murrell, is charged amid a police investigation into SNP funding and finances.

Thursday 18 April 2024 22:35, UK

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  • Latest updates from the Politics Hub With Sophy Ridge
  • Nicola Sturgeon's husband charged amid police investigation into SNP funding and finances
  • Davidson says she'll be 'surprised' if MP accused of misusing campaign funds 'survives the week'
  • Mood in Conservative Party 'very, very bleak'
  • Lancashire Police say no complaints made following allegations against Mark Menzies
  • Tories hit historic low in new poll - but there's bad news for Starmer as well
  • Number 10 declines to recommit to spring deadline for Rwanda flights
  • Explained: Why the legislation hasn't passed yet
  • Live reporting by Charlotte Chelsom-Pill and (earlier)  Faith Ridler

By Faye Brown , political reporter

Sir Keir Starmer said police should be involved in the case of suspended Tory MP Mark Menzies, who faces allegations he misused campaign funds.

The backbench MP for Flyde in Lancashire has lost the Conservative whip after The Times published claims he had used political donations to cover medical expenses and pay off "bad people" who had locked him in a flat and demanded thousands of pounds for his release.

Mr Menzies disputes the allegations, and the Conservative Party has said it is looking into the claims and takes them seriously.

The Labour leader told reporters during a visit to Teesside: "There are obviously a lot of unanswered questions in relation to these allegations. Not least why it seems the Conservative Party took so long to act and whether they've reported this to the police, who it seems to me should be involved in this."

He said there is a "degree of frustration" that two weeks away from the local elections "yet again we're talking about misbehaviour by Tory MPs".

Earlier, Defence Secretary Grant Shapps denied suggestions there was a problem within the Tory party, telling Sky News: "There are MPs from other parties that have experienced similar problems or misdemeanours and it is right that there are processes in place."

Read more here:

Senior Tory Ruth Davidson says she'll be "surprised" if MP Mark Menzies lasts the week, following allegations - which he denies - that he misused campaign funds. 

On the latest episode of Sky's   Electoral Dysfunction  podcast, which you'll be able to listen to from 6am on Friday, Baroness Davidson says the claims against him are "utterly jaw dropping".

"It is so out with the bounds of what being a responsible, elected member is and how you treat your constituency association. It is staggering, like utterly staggering," she says.

"I would find it difficult to believe that an investigation can be held and he can be cleared in time to stand a general election. 

"In fact, I would be surprised if he survives the week here and doesn't just resign."

Mr Menzies is alleged to have used thousands of pounds given by donors to fund medical expenses and to have made a late-night call to a party volunteer asking for help because he had been locked up by "bad people" demanding money for his release, according to The Times.

He has been suspended by the parliamentary party while it investigates the allegations.

The MP for Fylde in Lancashire, who was one of Rishi Sunak's trade envoys, disputes the allegations but the Conservative Party said it is taking them "seriously" and "will always investigate matters put to them".

Defence Secretary Grant Shapps told Sky News earlier: "There's a process in place. He has had the whip withdrawn. 

"There's further information that the chief whip I understand became familiar with yesterday and actions being swiftly taken on the basis of that further information. 

"I think it is important to stress that the MP in question here denies the allegations and so on basis of sort of fairness and proper justice, I think it’s important to mention that."

To hear more from Baroness Davidson's conversation with Sky's political editor  Beth Rigby   and Labour MP Jess Phillips, tune into the full episode of Electoral Dysfunction from 6am on Friday.

👉 Listen above then tap here to follow Electoral Dysfunction wherever you get your podcasts 👈

Nicola Sturgeon's husband and former SNP chief executive Peter Murrell has arrived back at home after being charged by police amid an investigation into the party's funding and finances.

He returned to the home he shares with Ms Sturgeon on the outskirts of Glasgow earlier this evening.

Police said he has been charged in connection with the embezzlement of funds from the party.

He was questioned by detectives after being taken into Police Scotland custody on Thursday at 9.13am.

He remained in police custody until he was charged just after 6.30pm.

An SNP spokesperson said: "While this development will come as a shock, the police investigation remains ongoing and it would, therefore, be inappropriate to make any comment." 

Over a year ago, Rishi Sunak made five pledges for voters to judge him on.

The prime minister met his promise to halve inflation by the end of 2023.

But with the general election approaching, how is Mr Sunak doing on delivering his other promises?

You can see the progress for yourself below:

The European Commission wants to open up post-Brexit talks which could make it easier for young Britons to study, work and live in the EU. 

It said it would ask EU Council member states permission to negotiate with the UK government on a youth mobility agreement.

It suggested Britain had shown interest in agreements with individual European nations, but said an EU-wide approach was preferable.

Downing Street, however, suggested bilateral schemes were in the UK's best interest.

Under the prospective deal proposed by the Commission, UK and EU citizens between the ages of 18 and 30 would be able to stay for up to four years in their destination country.

It would not amount to reinstating free movement, which the UK gave up when it left the EU. 

European Commission vice president Maros Sefcovic said: "The United Kingdom's withdrawal from the European Union has hit young people in the EU and the UK who would like to study, work and live abroad particularly hard.

"Today, we take the first step towards an ambitious but realistic agreement between the EU and the UK that would fix this issue. 

"Our aim is to rebuild human bridges between young Europeans on both sides of the Channel."

A No 10 spokeswoman said: "The UK does have at a bilateral level a number of such schemes in place and we do that where it's in the best interest of the UK.

"And we do it as long as it meets our requirement to balance bringing in skills to the UK and exchanging those skills, but at the same time making sure that it's in line with our objectives to also be promoting and fostering UK talents and skills.

"We have spoken about wanting to reduce legal migration and also about wanting to support UK talent and skills and that's why we have a system in place whereby we have a number of agreements with individual EU member states where that works in our interests and we have that rather than a Commission-wide agreement." 

Labour, meanwhile, has said it has "no plans for a youth mobility scheme".

Conservative MP Mark Menzies has been suspended from the parliamentary party in light of allegations he abused local Tory party funds to pay off "bad people".

Mark Menzies strongly disputes the claims which also include accusations he used campaign funds to pay his personal medical bills.

On the Conservatives' investigation into the claims, Defence Secretary Grant Shapps told Sky News: "There's further information that the chief whip I understand became familiar with yesterday and actions being swiftly taken on the basis of that further information.

"I think it is important to stress that the MP in question here denies the allegations and so on basis of sort of fairness and proper justice, I think it's important to mention that."

On the Sky News Daily, Niall Paterson is joined by political correspondent Darren McCaffrey to analyse how Westminster will cope with another scandal.

Plus, the Scottish government has come under fire for rowing back on its climate commitments.

Niall speaks to science correspondent Thomas Moore about the consequences of the government missing eight out of 12 of its annual climate commitments.

👉 Listen above then tap here to follow the Sky News Daily wherever you get your podcasts 👈

By Connor Gillies , Scotland correspondent

The climate gloves are off in a tale as old as time. Holyrood vs Westminster: the Green edition.

The SNP and its former leader Nicola Sturgeon stood on the global stage and won plaudits for their bold ambitions to help the slowdown in environmental doom.

Ms Sturgeon basked in a standing ovation when she boasted that Scotland was the first country on the planet to declare a “climate emergency”. But was it all talk? Was it without real substance?

The reality is the Edinburgh government, which includes Green Party ministers, has failed to hit its own targets for years and has faced claims of over promising and under delivering.

At Holyrood on Thursday, ministers climbed down from their big plans of reducing greenhouse gas emissions by 75% by the end of the decade while lashing out at cuts from Downing Street making it more difficult ( see post at 2.52pm ).

The reality is the fallout of Rishi Sunak’s backpedalling last year on the UK’s climate targets has impacted what Scotland can deliver within its constraints. Edinburgh was, in part, pinning plans on consequential cash from London.

But, is that the full story? Some would say the separate tartan targets were far from achievable.

Humza Yousaf told Sky News he is fully committed to net zero by 2045 which is still five years ahead of Westminster. It feels a political world away to say whether that date will also fall victim to tweaks and changes.

Nevertheless, it reveals the road to net zero continues to throw up surprises along the way.

People voting in local elections in England on 2 May will need to provide photo ID.

It is the second year the requirement has been in place - but in 2023,  14,000 people couldn't cast their ballot because they didn't take ID to the polling booth.

There are 22 different types of ID you can use - and if you don't have any of them, you can register for a Voter Authority Certificate.

Here's everything you need to know to avoid being caught out:

By Serena Barker-Singh , political correspondent

A former senior civil servant criticised some of the policymakers behind the illegal migration bill, accusing them of "harbouring racist views" about immigrants, it has emerged.

The senior policy official was in key ministerial meetings on the small boats policy, including in meetings with the then prime minister Boris Johnson.

Her claims emerged as part of an employment tribunal that has now concluded.

She says from her perspective the head of the illegal migration task force Michael Bourke and his deputy directors saw "the ultra-hostile environment towards unwanted foreigners as both being practical, necessary and gratifying".

In formal court documents seen by Sky News, the ex-head of policy in the illegal migration task force, who has been a civil servant for 12 years, said she had repeatedly tried to move conversations away from "prejudice and blame, to objective assessment and accountability".

Mr Bourke has stated his position is that his conduct towards the former civil servant was fair and during the time she was on the task force she was "negative and problematic, leading colleagues to feel disrespected, overburdened or undermined".

He denies she was treated less favourably and discriminated against on the grounds of her race or sex.

The progamme next turns to a lively discussion about former prime minister Liz Truss's book, detailing her short time in Downing Street. 

On the panel is Conservative commentator Tim Montgomerie who says: "I really have no time for Liz Truss. 

" Anyone with any sense of dignity would have absented themselves ... She should have gone and run a hotel in the Outer Hebrides or something.

"To actually still be at the forefront of politics without any real apology for what she did, I really think she's a disgrace, actually."

The conversation comes after the cabinet office confirmed the book is in breach of its rules. 

It says although the book was submitted for review, "we did not agree on the final wording". 

That concludes tonight's Politics Hub with Sophy Ridge.

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will travel at the speed of light ever be possible

IMAGES

  1. What happens if you travel at the speed of light?

    will travel at the speed of light ever be possible

  2. NASA Explains How to Travel at 99.9 Percent of the Speed of Light

    will travel at the speed of light ever be possible

  3. Journey Through The Universe At The Speed Of Light (4K UHD)

    will travel at the speed of light ever be possible

  4. WATCH

    will travel at the speed of light ever be possible

  5. Will Light-Speed Space Travel Ever Be Possible?

    will travel at the speed of light ever be possible

  6. What is the Speed of Light?

    will travel at the speed of light ever be possible

VIDEO

  1. Interstellar Travel possible or not ?? #shorts #short #viral #wormhole

  2. What If You Could Travel at the Speed of Light😳🚀 #factsintelugu #threeightexplains

  3. Does Traveling at Light Speed Have a Limit? A Journey Beyond Time

  4. If it was possible to travel faster than the speed of light, would time reverse itself

  5. Is it possible to travel at the speed of light🤯

  6. What Will Happen If We Travel At The Speed Of Light? #shorts

COMMENTS

  1. Will Light-Speed Space Travel Ever Be Possible?

    The idea of travelling at the speed of light is an attractive one for sci-fi writers. The speed of light is an incredible 299,792,458 meters per second. At that speed, you could circle Earth more than seven times in one second, and humans would finally be able to explore outside our solar system. In 1947 humans first surpassed the (much slower ...

  2. What Would Happen If You Traveled At The Speed Of Light?

    When you traveled to Mars at 90% light speed, humanity on Earth was older by 16.67 minutes, while you aged by just 8.33 minutes! This difference in aging would become much more pronounced at higher speeds, say at 99.99% the speed of light. At 99.99% Speed Of Light. Now, suppose you could travel at 99.99% of the speed of light.

  3. Warp drives: Physicists give chances of faster-than-light space travel

    The fastest ever spacecraft, the now- in-space Parker Solar Probe will reach a top speed of 450,000 mph. It would take just 20 seconds to go from Los Angeles to New York City at that speed, but it ...

  4. Three Ways to Travel at (Nearly) the Speed of Light

    1) Electromagnetic Fields. Most of the processes that accelerate particles to relativistic speeds work with electromagnetic fields — the same force that keeps magnets on your fridge. The two components, electric and magnetic fields, like two sides of the same coin, work together to whisk particles at relativistic speeds throughout the universe.

  5. Scientists Believe Light Speed Travel Is Possible. Here's How

    Here's How. Scientists Believe Light Speed Travel Is Possible. Here's How. A functioning warp drive would allow humans to reach the far ends of the cosmos in the blink of an eye. n late 2020 ...

  6. Warp Speed Travel Is Theoretically Possible, Says Astrophysicist

    And that's something we need if we ever want to get serious about exploring the Universe. "Even travelling at the speed of light, it would take four years to go to the nearest star and 2 million years to go to the nearest large galaxy," said Lewis. "[These distances] would stop you colonising the Universe … so you would need some sort of way to beat that speed limit, and Einstein's theory of ...

  7. Why you can't travel at the speed of light

    This explains why nothing can travel faster than light - at or near light speed, any extra energy you put into an object does not make it move faster but just increases its mass. Mass and energy ...

  8. Warp drives: Physicists give chances of faster-than-light space travel

    If humanity ever wants to travel easily between stars, people will need to go faster than light. But so far, faster-than-light travel is possible only in science fiction.

  9. Speed of light: How fast light travels, explained simply and clearly

    In fact, we now define the speed of light to be a constant, with a precise speed of 299,792,458 meters per second. While it remains a remote possibility in deeply theoretical physics that light ...

  10. Faster-Than-Light Travel Could Work Within Einstein's Physics

    There are still plenty of puzzles to solve, but the free-flow of these kinds of ideas remains our best hope of ever getting a chance to visit those distant, twinkling stars. "This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering," Lentz said.

  11. The Casimir Effect: Unlocking a Mind-Boggling Part of Reality

    Hendrik Casimir's idea for an experiment was simple: bring two metallic objects extremely close together and wait. Spontaneously, as if by magic, the objects will be drawn together. No external ...

  12. Here's What Would Happen If You Could Travel at the Speed of Light

    Finally, the video tackles the fact that even if you were moving at the speed of light, the "universe is also a very big place, so you might be in for some surprises." For example, your rocket's ...

  13. Is time travel possible? An astrophysicist explains

    Time gets a little strange as you approach the speed of light. FlashMovie/Shutterstock Will it ever be possible for time travel to occur? - Alana C., age 12, Queens, New York.

  14. Research Shows Faster-Than-Light Warp Speed Is (Probably) Possible

    Warp speed could be entirely possible. The secret to faster-than-light physics could be to double down on the number of dimensions, according to new research. Search

  15. Have we made an object that could travel 1% the speed of light?

    The fastest things ever made by humans are spacecraft, and the fastest spacecraft reached 330,000 mph - only 0.05% the speed of light. But there are ways to go faster.

  16. Can anything travel faster than the speed of light?

    So, according to de Rham, the only thing capable of traveling faster than the speed of light is, somewhat paradoxically, light itself, though only when not in the vacuum of space. Of note ...

  17. Is Interstellar Travel Really Possible?

    Once accelerated to one-tenth the speed of light, the real journey begins. For 40 years, this little spacecraft will have to withstand the trials and travails of interstellar space. It will be ...

  18. Is Time Travel Possible?

    In Summary: Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

  19. How to Travel at (Nearly) the Speed of Light

    The theory of special relativity showed that particles of light, photons, travel through a vacuum at a constant pace of 670,616,629 miles per hour — a speed that's immensely difficult to achieve and impossible to surpass in that environment. Yet all across space, from black holes to our near-Earth environment, particles are, in fact, being ...

  20. No, the expanding Universe doesn't break the speed of light

    And for an object 33 billion light-years away, the current cosmic record for most distant galaxy, we infer a recession speed of 708,000 km/s: more than double the speed of light.

  21. Could a telescope ever see the beginning of time? An astronomer explains

    All light - whether sunlight, a flashlight or a light bulb in your house - travels at 186,000 miles (almost 300,000 kilometers) per second. That's just over 11 million miles (about 18 ...

  22. Could A Telescope Ever See The Beginning Of Time?

    Or, as scientists like to say, four light years. Most recently, JWST observed Earendel, one of the farthest stars ever detected. The light that JWST sees from Earendel is about 12.9 billion years old. The James Webb Space Telescope is looking much farther back in time than previously possible with other telescopes, such as the Hubble Space ...

  23. Israel vs. Iran: What an All-Out War Could Look Like

    Listen. 5:37. Iran's massive missile and drone attack on Israel, which began in the late hours of April 13, pushed the conflict between the two countries into a potentially explosive new phase ...

  24. Faster-Than-Light Travel Is Possible Within Einstein's Physics

    Faster-Than-Light Travel Is Possible Within Einstein's Physics, Astrophysicist Shows. Space 11 March 2021. ... While pushing matter past the speed of light will always be a big no-no, spacetime itself has no such rule. ... the far reaches of the Universe are already stretching away faster than its light could ever hope to match.

  25. Middle East latest: Iran tells Israel 'our hands are on the trigger

    US officials have flatly denied reports (see our 1.15pm post) that the Biden administration gave a green light to Israel's plans to assault Rafah in return for Israel holding off on striking Iran ...

  26. Politics latest: Tories hit historic low in new poll

    Politics latest: Tories hit historic low in new poll - but there's bad news for Sir Keir Starmer as well. One polling firm has the Tories on 19%, the lowest level of support it has ever recorded ...