Are you a journalist? Please sign up here for our press releases. How much time does it take to send a package from New York to Tel Aviv, and how does that compare with sending an email from one side of the Weizmann Institute of Science campus to the other?
Now shrink the package down to the size of one of the electrons making up the email and put up an impenetrable barrier over the ocean. Eli Pollak , together with postdoctoral fellow Dr. Randall Dumont of McMaster University in Canada, recently provided theoretical support for this idea.
This effect, or an optical shockwave, is called Cherenkov radiation. It is only visible with the naked eye if the object is travelling extremely quickly and through quite a dense material. Nuclear reactors will spew out electrons at high speeds, since these are by-products of the very same nuclear reaction.
Interestingly, these electrons travel faster than the speed of light in water, causing shockwaves of light. Air is very close to being a vacuum but it will never be a perfect vacuum.
For this reason, the speed of light in the air around us is slightly slower than the speed of light in a vacuum, or c.
This means that it is technically possible for something to break the light barrier in regular air without breaking fundamental laws and limits of the speed of light in a vacuum. But you are not as likely to see the blue glow of the Cherenkov radiation in air than you are in water. This is simply because you would have to travel faster in air than water, since water is a denser medium, so the speed of light is slower.
That is not to say that it never happens in air though. We can actually see examples of this from earth. Some of these cosmic rays are even fast enough to create the optical shockwave when they travel through air around earth. This is too faint to see with a naked human eye, but we have been able to record this Cherenkov radiation with the use of cameras. If you wave a flashlight across the night sky, then, in principle, its image can travel faster than light speed since the beam of light is going from one part of the Universe to another part on the opposite side, which is, in principle, many light years away.
The problem here is that no material object is actually moving faster than light. Imagine that you are surrounded by a giant sphere one light year across.
The image from the light beam will eventually hit the sphere one year later. This image that hits the sphere then races across the entire sphere within a matter of seconds, although the sphere is one light year across. Just the image of the beam as it races across the night sky is moving faster than light, but there is no message, no net information, no material object that actually moves along this image.
Quantum entanglement moves faster than light. If I have two electrons close together, they can vibrate in unison, according to the quantum theory. If I then separate them, an invisible umbilical cord emerges which connects the two electrons, even though they may be separated by many light years.
Einstein thought that this therefore disproved the quantum theory, since nothing can go faster than light. Quantum tunneling is a well known phenomenon that occurs as a direct result of the strange uncertainty which pervades nature at very small scales. It allows subatomic particles to break apparently unbreakable barriers. Even if the discovery turns out to be real, IBRS's McIsaac isn't convinced that it could be turned into a useful product: "About 15 or 20 years ago a scientist claimed to have discovered cold fusion One of the big promises has been quantum computing and we still don't have it.
Also, photonic computing — we still don't have that either. Quantum tunneling To understand the principle of quantum tunneling, consider a ball being bowled up a hill. If the ball has insufficient velocity, it will not roll over the top of the hill and appear on the other side. But, if the ball was a subatomic particle, subject to quantum laws, it would also behave like a wave.
The "wave function" describing the particle would represent the probability of finding it at a certain location. This wave could extend to the other side of the hill, meaning there will always be a small possibility of the particle being detected there unexpectedly.
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