Particle Physics and Faster-Than-Light Neutrinos…Discuss.

On September 22, an international team of researchers working on the OPERA project at the Gran Sasso research facility released a paper on some potentially physics-shattering findings: beams of neutrinos that had traveled from the CERN facility near Geneva to their detector array outside of Rome at a speed faster than light. (Read more about this here and here.) Not a great deal faster, to be sure – only 60 nanoseconds faster than expected – but still faster. There’s been a lot of recoil from the scientific community about this announcement, and rightly so, since if it does end up being a legitimate finding then it would force us to rework much of what we have come to know about physics ever since Einstein’s theory of relativity.

Of course, to those of us not so well-versed in particle physics *raises hand* a lot of this information can quickly become overwhelming, to say the least. Thankfully the folks at Sixty Symbols have recorded this interview with two astrophysicists at the UK’s University of Nottingham. It helps explain some of the finer points of the discovery, what it means and what the science community in general thinks about it. Check it out!

Thanks to Dan Satterfield for posting this at his Wild Wild Science blog.

Tachyon

Tachyon

[/caption]Ever since Einstein unveiled his theory of relativity, the speed of light has been considered to be the physical constant of the universe, interrelating space and time. In short, it was the speed at which light and all other forms of electromagnetic radiation were believed to travel at all times in empty space, regardless of the motion of the source or the inertial frame of reference of the observer. But suppose for a second that there was a particle that defied this law, that could exist within the framework of a relativistic universe, but at the same time defy the foundations on which its built? Sounds impossible, but the existence of such a particle may very well be necessary from a quantum standpoint, resolving key issues that arise in that chaotic theory. It is known as the Tachyon Particle, a hypothetical subatomic particle that can move faster than light and poses a number intriguing problems and possibilities to the field of physics.

In the language of special relativity, a tachyon would be a particle with space-like four-momentum and imaginary proper time. Their existence was first attributed to German physicist Arnold Sommerfeld; even though it was Gerald Feinberg who first coined the term in the 1960s, and several other scientists helped to advance the theoretical framework within which tachyons were believed to exist. They were originally proposed within the framework of quantum field theory as a way of explaining the instability of the system, but have nevertheless posed problems for the theory of special relativity.

For example, if tachyons were conventional, localizable particles that could be used to send signals faster than light, this would lead to violations of causality in special relativity. But in the framework of quantum field theory, tachyons are understood as signifying an instability of the system and treated using a theory known as tachyon condensation, a process that attempts to resolve their existence by explaining them in terms of better understood phenomena, rather than as real faster-than-light particles. Tachyonic fields have appeared theoretically in a variety of contexts, such as the bosonic string theory. In general, string theory states that what we see as “particles” —electrons, photons, gravitons and so forth—are actually different vibrational states of the same underlying string. In this framework, a tachyon would appear as either indication of instability in the D-brane system or within spacetime itself.

Despite the theoretical arguments against the existence of tachyon particles, experimental searches have been conducted to test the assumption against their existence; however, no experimental evidence for the existence of tachyon particles has been found.

We have written many articles about tachyon for Universe Today. Here’s an article about elementary particles, and here’s an article about Einstein’s Theory of Relativity.

If you’d like more info on tachyon, check out these articles from Science World. Also, you may want to browse through a forum discussion about tachyons.

We’ve also recorded an entire episode of Astronomy Cast all about the Theory of Special Relativity. Listen here, Episode 9: Einstein’s Theory of Special Relativity.

Sources:
http://en.wikipedia.org/wiki/Tachyon
http://en.wikipedia.org/wiki/Speed_of_light
http://scienceworld.wolfram.com/physics/Tachyon.html
http://en.wikipedia.org/wiki/D-brane
http://www.nasa.gov/centers/glenn/technology/warp/warp.html