At the time of the release of the Princeton Lab findings, the head researcher for the experiment, Dr. Liujun Wang, stated that “Our experiment shows that the generally held misconception that nothing can move faster than the speed of light, is wrong. Einstein’s Theory of Relativity still stands, however, because it is still correct to say that information cannot be transmitted faster than the vacuum speed of light.”

But hold on. Enter quantum physics. In experimental results published on February 8, 2018, in the Journal of Physical Review Letters, in an article entitled, “Two-Way Communication with a Single Quantum Particle,” two quantum physicists,  Jinyang Liang and Lihong V. Wang, from the Unversity of Vienna, demonstrate that quantum systems can surpass the speed limit of light.

Their experiment involves the exchange of a single quantum particle (a photon) by two individuals at the same time with both in receipt of the results in half the normal time of a transmission traveling at the speed of light.

Why is it even possible to exceed the speed of light by double? Because of quantum superposition. That is the single photon each participant in the experiment sends gets canceled or transposed at the same time. The end result, the single photons end up in two places simultaneously.

Is there a practical application for this discovery? Theoretically, this technique could be used for the sending and receiving of secure communications where no third-party could eavesdrop on messages sent and received.

If you are not familiar with superposition, it is a strange phenomenon at the quantum scale. We can observe superposition when we throw two pebbles in a pond and watch the waves created spread in rings until they intersect and cancel out each other.

In quantum states, the analogy of waves on a pond is applicable. The quantum particle strikes the pond surface in one state which then becomes a wave, a series of ripples, a separate state. The ripples move outward and may encounter other ripples which effectively cancel out the wave. What happens to the quantum particle? It still exists but it has undergone a change of states. Thus it is both particle and wave, existing in different states simultaneously.

Some argue that in the experiment described above that the quantum particle in our physical world never really moves because it already exists in the quantum world in two places or two states. Yet we know in this experiment that individual particles have been both fired and received.

Are you confused? Watch this video and maybe it will help.

Of course, this brings up the idea of humanity at some point being able to travel at speeds faster than light, bringing unreachable stars closer to us and making the world of Star Trek no longer science fiction? We have a while to go before anyone can turn a single photon traveling faster than light into a starship doing the same.

Of course, Einstein’s explanation of what is light, both a particle and a wave, (described as wave-particle duality) get discussed on a number of occasions. And exactly what does Einstein tell us about light?

• In a vacuum, light travels at 299,792 kilometers (186,000 miles) per second. That means light from the Sun takes on average about 8.3 minutes to reach us here on Earth. So if the Sun were to wink out as I write these words, we wouldn’t know it until approximately 8 minutes later. And if we were on Mars we wouldn’t know it for almost an additional 5 minutes after passing Earth.
• The theory of general relativity reinforces the notion that light speed is a constant which produces some interesting thought exercises such as:
  • If we were to travel in a spacecraft at the speed of light from the perspective of those watching us from Earth time would continue to tick by, but for us time would slow down and stop, and upon our return to Earth we wouldn’t have aged at all while those who stayed on the planet would be much older.
  • Or if we were to exceed the speed of light then theoretically time would go backward.

But our understanding of the constancy of light is being shaken by questions scientists pose to better understand how the Universe looks today and what it may have been like the moment of its birth, the Big Bang.

Cosmologists look at the Universe today and question inflation after the Big Bang because they don’t understand the uniformity they see in the background temperature of space. From one end of the observable Universe to the other, there is no variance. This calls into question the moment of the Big Bang itself with light traveling out from the centre to the outer edge traveling at a constant speed. Why aren’t there pockets of the Universe warmer than other areas? The only way uniformity can exist is if light energy exchanges occurred throughout space from the beginning. But light traveling in one direction from the Big Bang could never exchange energy with light traveling in the opposite direction. So space’s background temperature should not be uniform because there would no opportunity for energy exchanges to create it.

The cosmological puzzle of uniformity of background temperatures has brought into question Einstein’s theory that light travels at a constant speed and has done so forever. New hypotheses suggest inflationary theories of the Universe after the Big Bang may be wrong and that light, at the moment of the Big Bang, the beginning of space-time, traveled at near infinite speed.

Niayesh Afshordi, Associate Professor, University of Waterloo, is one of a number of physicists who suggest that in going back to a point when the Universe was hot just after the Big Bang, temperatures would have been ten thousand trillion degrees Celsius. Under such conditions light may have behaved far differently.

Afshordi isn’t questioning the observable speed of light as we know it today. He and others argue that the only explanation for what we are observing through the data our telescopes and satellites are collecting today, suggests a very different model. Light may very well have traveled at very different speeds in the past.

Other physicists also look at the voids in the Universe, areas that appear empty, and speculate that they aren’t as they appear, that they are packed with particles in altering states caused by quantum fluctuations. They propose that quantum fluctuations slow the speed of light.

And in fact, physicists from the University of Glasgow and Heriot-Watt in laboratory experiments have demonstrated that a single photon of light can be slowed down in a vacuum by having it travel on an oval track. Doing this the researchers demonstrated light speed diminished over a distance and time by a fraction of a millimeter. That’s something that would have had Einstein doing some real head scratching.

Further experimentation on the theoretical limits of the speed of light will be put to the test when the James Webb telescope is launched next year and we will for the first time see back 13.5 billion years to the beginning of space-time. That should make for some interesting new takes on cosmology and our understanding of the Big Bang and the properties of light as an inconstant or constant.