Sir Einstein, through his Special theory of relativity concluded that no object can start and accelerate to a speed more than the speed of light, this is also called the ‘speed of light barrier’, which means that the universal speed limit is 299,792,458 m/s aka the speed of light. In layman’s language, if an object started with a speed which is less than the speed of light, can never cross the speed of light barrier. But this opens the possibility that there may be a particle that always and forever is traveling faster than the speed of light so it was never required to cross over the barrier.

Such particles are called **Tachyons**. These particles were earlier called Meta Particles but when in 1966, “Gerald Feinberg” came up with his ideas about these particles, he coined the term Tachyons. Tachyons are hypothetical particles which exist while always having a speed that is way more than the speed of light. Here, ‘hypothetical’ refers that they exist just in theory yet.

**Expected properties of Tachyons**

The Rest mass, Proper length and Proper lifetime of Tachyons will be imaginary. This can be proved through mathematical formulae of relativistic mass, length, time.The speed of Tachyon increases as it loses energy via Cherenkov radiation. In case, energy is supplied to Tachyons they slow down which means their speed decreases. As Tachyons always travel faster than the speed of light, it will allow us to send messages to our past.

Until these particles completely satisfy the mathematical equations there is no doubt in their existence.

But some physicist don’t imply their existence because-

They violate the principle of causality.

Gives birth to different time travel

**paradoxes**.

**For Example**-Grandfather’s Paradox, Tachyon Telephone Paradox and many more.

Even though some physicist give possible solutions for these paradoxes by using the concept of **parallel universe,** but the problem is that the existence of parallel universe hasn’t been proven yet.

*Written by: Aaryan Salgania*
*Aaryan Salgania is *__volunteering__* for Voyager Space Outreach to write Blog Posts on STEM/Space Topics.*