Nothing can travel faster than 300,000 kilometers per second (186,000 miles per second). Only massless particles, including photons, which make up light, can travel at that speed. It's impossible to accelerate any material object up to the speed of light because it would take an infinite amount of energy to do so.
These particles, which he called tachyons, would never travel slower than the speed of light. In fact, they would be forced to always go above light speed and would have just as much difficulty slowing down to light speed as we do trying to accelerate to it.
A tachyon (/ˈtækiɒn/) or tachyonic particle is a hypothetical particle that always travels faster than light. Physicists believe that faster-than-light particles cannot exist because they are not consistent with the known laws of physics.
In special relativity, the speed of light is the ultimate speed limit to the universe. Nothing can travel faster than it.
Darkness travels at the speed of light. More accurately, darkness does not exist by itself as a unique physical entity, but is simply the absence of light. Any time you block out most of the light – for instance, by cupping your hands together – you get darkness.
So light is the fastest thing. Nothing can go faster than that. It's kind of like the speed limit of the universe.
If you were able to travel at the speed of light, all of your motion would be wrapped up in getting you to travel at the maximum speed through space, and there would be none left to help you travel through time — and, for you, time would stop. At the speed of light, there is no passage of time.
At any rate, the beam of light emitted by your flashlight would appear to reach the far wall instantly, as the speed of light is independent of your speed and would always be constant at about 300,000 kilometres per second in a vacuum.
Answer: Firstly, the physical consequence of traveling at the speed of light is that your mass becomes infinite and you slow down. According to relativity, the faster you move, the more mass you have. The same works on Earth when you're driving down the freeway.
Yet despite this incredible journey, the photon itself experiences none of what we know as time: it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time. Given everything that we know, a photon never ages in any way at all.
Because space isn't curved they will never meet or drift away from each other. A flat universe could be infinite: imagine a 2D piece of paper that stretches out forever. But it could also be finite: imagine taking a piece of paper, making a cylinder and joining the ends to make a torus (doughnut) shape.
Methuselah: The oldest star in the universe. Space.
These explosions generate beams of high-energy radiation, called gamma-ray bursts (GRBs), which are considered by astronomers to be the most powerful thing in the universe. What's more, these GRBs could be killing our chances of ever discovering life on other planets.
speed of sound, speed at which sound waves propagate through different materials. In particular, for dry air at a temperature of 0 °C (32 °F), the modern value for the speed of sound is 331.29 metres (1,086.9 feet) per second.
In 1998, Danish physicist Lene Vestergaard Hau led a combined team from Harvard University and the Rowland Institute for Science which realized much lower group velocities of light. They succeeded in slowing a beam of light to about 17 meters per second.
Color paints are mixed together to create darkness, because each color absorbs certain frequencies of light. Theoretically, mixing together the three primary colors, or the three secondary colors, will absorb all visible light and create black.
Spirals, ellipticals, and irregulars are all more common than ring galaxies. At last, we know how these ultra-rare objects are made. Discovered in 1950, this galaxy is known as Hoag's object, and is the first known instance of a ring galaxy.
In the beginning, there was an infinitely dense, tiny ball of matter. Then, it all went bang, giving rise to the atoms, molecules, stars and galaxies we see today. Or at least, that's what we've been told by physicists for the past several decades.
The trite answer is that both space and time were created at the big bang about 14 billion years ago, so there is nothing beyond the universe. However, much of the universe exists beyond the observable universe, which is maybe about 90 billion light years across.
Scientists now consider it unlikely the universe has an end – a region where the galaxies stop or where there would be a barrier of some kind marking the end of space. But nobody knows for sure.
The universe will get smaller and smaller, galaxies will collide with each other, and all the matter in the universe will be scrunched up together. When the universe will once again be squeezed into an infinitely small space, time will end.
Observations suggest that the expansion of the universe will continue forever. The prevailing theory is that the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario once popularly called "Heat Death" is now known as the "Big Chill" or "Big Freeze".
Near a black hole, the slowing of time is extreme. From the viewpoint of an observer outside the black hole, time stops. For example, an object falling into the hole would appear frozen in time at the edge of the hole.
Light is actually energy made of small particles called photons.