The laws of the universe as we know it could all change - because of one strange particle

Tachyons might sound like creatures ripped out of a George R. R. Martin novel, but the reality is that they refer to as-yet-non-existent particles not only capable of travelling faster than the speed of light, but also of changing our understanding of the universe.

The speed of light - exactly 299,792,458 metres per second – has already given us a lot of ideas about space and the universe, such as a lightyear which, in addition to being the surname of an animated children’s character, also pertains to how many years it would take you to travel somewhere if you were going at the speed of light.

What’s more, when looking up at the night’s sky, the stars we see are shining from the past, as that light has taken a considerable amount of time to reach us.

And if we were to cut the travel part out of that equation and arrive at the source immediately, then that messes with the concepts of causality (basically, cause and effect) and relativity (how objects behave in space-time), raising questions around time travel and warp speed, too.

In 1994, a physicist called Dr Miguel Alcubierre, of the University of Wales in Cardiff, took Albert Einstein’s theory of general relativity (different to special relativity, and concerning the concept of a space-time continuum of which gravity is a warp in this ‘fabric’) and concluded a ‘warp drive’ was possible, but required “negative energy”.

More recently, in May last year, University of Alabama researchers looked into whether such a ‘warp drive’ could actually be produced by something more familiar – namely particles underpinning the creation of planets and humans.

And they could use more ordinary matter to produce such a phenomenon, but only at sub-light speed, and lead researcher Dr Jared Fuchs told BBC Science Focus that “you need a lot of energy to make any small change in space”.

The outlet writes: “To move a passenger compartment the size of a small room would require a ‘warp bubble’ the size of a small house. And to make that would require squeezing a few times the mass of Jupiter into a volume the size of a small asteroid.”

Meanwhile Dr Fuchs said that although the possibility of that is a “maybe”, he “wouldn’t say” that it’s practical, given it again raises challenges around the sheer amount of energy required.

But that brings us back to tachyons, which Polish professor Andrzej Dragan says “make perfect sense mathematically”, and that while the familiar particles we’ve come across are subluminal (that is, slower than the speed of light), they could be hanging about with superliminal particles which are tachyons.

Though again, a question of energy comes up when it comes to slowing such particles down to the subliminal speeds we recognise.

Except there’s another familiarity which was identified by Dragan, namely that they defied the strict cause and effect of causality (see above) which we see in subatomic particles.

To be specific, an atom can absorb a light photon and then emit it at a later stage, but we won’t know in exactly which direction that will be – and Dragan is suggesting an interaction between a tachyon and ordinary matter could bring about an outcome which is just as unpredictable.

It doesn’t follow strict cause and effect, because we only have the latter as something observable.

And so, to summarise, the bright beams of light you see blasted in the faces of space pilots in media such as Star Trek and Star Wars is being thought about, but significant challenges and questions remain.

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