![]() "We could get close, but never quite reach it." "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. "But sending actual physical humans at the speed of light is simply impossible, because we cannot accelerate ourselves to such speed. "We can imagine being able to communicate at the speed of light with systems outside our solar system," de Rham said. 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 (opens in new tab) that could enable faster-than-light travel," Cassibry said. This would indicate that it would probably not be desirable to make a human travel faster than the speed of light. "There could be situations where the future could affect our past, and then the whole structure of reality would stop making sense." But what does this mean? "If someone 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. 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. (Image credit: WinWin artlab via Shutterstock) In this case, space-time is expanding, but the material in space-time is still traveling within the bounds of light speed.Ī diagram of the visible color spectrum. 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. For example, the Hubble Space Telescope recently spotted 12.9 billion year-old light from a distant star known as Earendel. "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. Universal lookĪccording to Cassibry, however, there is something else to consider when discussing things moving faster than the speed of light. Of note, regardless of the medium, light will never exceed its maximum speed of 186,282 miles per second. 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. 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. "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). When light travels through a vacuum, however, the same is not true. 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 (opens in new tab). 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." 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. Light exhibits both particle-like and wave-like characteristics, and can therefore be regarded as both a particle (a photon) and a wave. But there are certain caveats to consider, she said. ![]() "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. ![]()
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