Welcome back to Gaming On the Fringe. In two previous articles we’ve looked at ways of skirting the lightspeed barrier to allow “effective” faster than light (FTL) travel. What this means is that technically the starship in question never itself traveled at FTL speeds – i.e. above 186,000 miles per second – but found a clever way around it. While relativity does state that nothing can accelerate to lightspeed, let alone exceed it, what about something that never travels slower than lightspeed? Enter the tachyon.
While I will of course explain in more detail later on, the tl;dr is that tachyons are hypothetical particles that are always traveling FTL. The relativity barrier works both directions so these can never slow below lightspeed. While these particles are currently hypothetical, video games work on fiction so they can get around that. Let’s examine some ways games use tachyon technology.
Stellaris is a 4X based space simulation where you command a species in real time space strategy action. Our own Matt Faherty discussed the game before, but I’m looking at just one technology you can research in game. It’s highly interesting for a sci-fi scenario in that while most settings feature the same technology applied universally by all races, this one does not. You can have ships with warp drive right along ships that use hyperspace or those that use wormholes. This extends into weaponry as well. While some ships feature relativistic mass accelerators – that’s another article – you can choose for your race to favor energy weapons. One of the most powerful is the Tachyon Lance.
Essentially, the Tachyon Lance is a more powerful version of a particle lance. A particle lance simply flings high speed (massive fractions of the speed of light, or c) as a weapon. However, why stick to relativistic speeds when you can shoot FTL munitions? The advantages of a tachyon weapon is that by the very nature of FTL travel the target would never see it coming. Instead of something like a laser turret, which by nature travels at lightspeed, you get a particle beam weapon that is physically impossible to see. You don’t have to be a disciple of Sun Tzu to grasp the power of such a weapon.
Stellaris also uses tachyons for a more obvious technology. The Tachyon Sensors tech allows your ships to detect objects at a much farther range than other scanners can. Considering that a sensor based on tachyons would be able to pick up signals faster than the light transmitted from the objects, this would be a boon for any space military. Unless your enemy has realspace FTL, you would be able to detect them before they have any way of seeing your ships, or you seeing theirs. There would be no chance of ambushes as you would be able to sense your enemies before they even know you have arrived. Conversely, it would be very easy to set up ambushes for enemies since you can track their movements without being seen.
While Stellaris certainly has interesting applications of tachyons, I would be remiss to not mention Tachyon: The Fringe in this article. This epic space dogfighting simulator uses the eponymous tachyons to enable all faster than light travel or communications. Most ships in the game aren’t big enough to have any built-in FTL capability so they use stationary gates that use Tachyon Coil Generators to traverse light years. Although very large ships may carry a generator that allows them to travel where they would like, without gates. Interestingly, this game apparently uses tachyons to create what are essentially wormholes despite the two having no relationship in physics.
Tachyon: The Fringe makes use of tachyons almost purely for FTL travel, with no mention of FTL communications besides ships carrying messages back and forth. I find it interesting that for a game named after the particle they do nothing with it but use it as a piece of phlebotinum for what is essentially hyperspace travel. The use of gates for smaller vessels but on-board tachyon generators for larger ships actually parallels the tv series Bablyon 5, which had just concluded a few years before the game’s release.
Alright, let’s look at the “real world” version of tachyons. As I stated before, this is purely theory at this point, so I don’t see the need to mention that every other sentence. Just assume that anything mentioned from here on out is simply mathematics with no physical evidence as of yet. I’ve mentioned a lot in this series that nothing with mass can achieve lightspeed, let alone exceed it. However, this also works in reverse. If a particle starts as FTL, it can never slow down enough to reach lightspeed or slower. It does take energy to slow down anything in motion so the energy to slow down an FTL particle to just lightspeed would then become infinite.
You might be an educated reader who is asking how any massed particle can even begin existence at FTL speeds, and that would be a great question. Tachyon theory involves the particles possessing imaginary mass. If you remember high school algebra then you know that imaginary numbers are where imaginary mass gets its name. Any imaginary number when squared produces a negative number, instead of a positive one. An imaginary mass when increased due to speed and relativistic mass would decrease, which is why a tachyon can always accelerate far beyond lightspeed. However, going the opposite direction would still create an infinity, and negative or not, infinities are impossible.
Impossible is unfortunately a word that will be used a lot while discussing tachyons. The fact is that in all likelihood tachyons of this sort are just not possible, and that’s proven with the tachyonic antitelephone paradox. The wikipedia page details it far better than I could, but here’s a shot. Essentially, the use of an FTL communications device could allow for some observers to see events happen before their causes. All this flows from relativity declaring there are no special frames of observation.
Causality, or the flow of cause and effect, is one of the absolute bedrocks of science. If two travelers are traveling in opposite directions close to the speed of light, but have tachyon communicators, we can see this in action. Due to each traveler experiencing time dilation relative to the other, there are paths in which one traveler could receive a reply to a message they haven’t sent yet. If you sent a tachyonic signal from Earth to Mars, and got a response, it would be instantaneous. A starship traveling slower than light closer to Mars than Earth would see Mars respond before the message was received. This breakdown of basic causality is a feature in most FTL scenarios and is a major reason why many scientists call it impossible. There have been various claims around it – most featuring some variant of the Novikov self-consistency principle but that’s more in depth than I plan to go into here.
One question that might be in your heads is “what would a tachyon look like,” and the answer is actually pretty interesting. Due to it traveling faster than light you obviously wouldn’t be able to see the particle coming, but you could see the after effects. If you’re in the path of a tachyon as it passes you, two separate images would appear. An image of the tachyon going both directions from you would appear, along with a blast of Cerenkov radiation. This is a bluish radiation emitted by particles that exceed the speed of a light in a medium – the blue light from an underwater nuclear reactor is an example. So by the act of the particle going FTL past you, there would be two images. I said this was interesting, I didn’t say it wasn’t weird.
Unfortunately, there seems to be little evidence that tachyons can exist, let alone actually do. While there are mass fields that exist called tachyons, they are not superluminal. The combination of paradoxes and difficulty in creating an imaginary mass conspire to reduce tachyons to interesting mathematical constructs, not actual particles. Now, they are still predicted by some versions of string theory so we may one day find ourselves with tachyons, but I wouldn’t hold my breath.
Something I’ll revisit a lot in this series is science fiction ideas that are sadly incompatible with known physics. Tachyons, despite their many uses in fiction, simply don’t fit with the law of physics as we know them today. That doesn’t mean they make for bad science fiction, just bad physics. As they stand now, they are just interesting thought experiments, but one can always dream. I hope you enjoyed this article, and maybe even learned something. See you next time.