Editing Tachyon (section)

=== Speed ===
One curious effect is that, unlike ordinary particles, the speed of a tachyon ''increases'' as its energy decreases. In particular, <math> E </math> approaches zero when <math> v </math> approaches infinity. (For ordinary bradyonic matter, ''<math> E </math>'' increases with increasing speed, becoming arbitrarily large as ''<math> v </math>'' approaches '''''<math> c </math>''''', the [[speed of light]].) Therefore, just as bradyons are forbidden to break the light-speed barrier, so are tachyons forbidden from slowing down to below ''c'', because infinite energy is required to reach the barrier from either above or below.

As noted by [[Albert Einstein]], [[Richard C. Tolman]], and others, [[special relativity]] implies that faster-than-light particles, if they existed, [[Tachyonic antitelephone|could be used to communicate backwards in time]].<ref name="Benford" />