Suppose we suddenly had proof of a super-luminal event - something going faster than the speed of light. I’ll leave the details of the event deliberately obscure but assume that we have absolute proof. What would be the ramifications of this be to science? To humanity?
We already have the ‘spooky’ action at a distance quantum entanglement and that doesn’t seem to stop people claiming the speed of light as an absolute barrier to interplanetary space travel forever and ever.
I’d hope it would make people realise that we don’t know anything like everything.
Well, we’d have to find a way to deal with losing that nice ‘effect follows cause’ relationship most of us are pretty fond of, for starters…
It would be great for science. Suddenly, physicists could rule out any theories that flatly forbid FTL travel, and concentrate on the ones that have loopholes that allow it.
It adds more point to the Fermi Paradox; FTL being possible adds more point to the “where are they ?” question.
It doesn’t stop people because it isn’t the loophole you seem to think it is. No information can be transmitted in this manner, which is what the speed-of-light barrier really signifies. Moving a spaceship–or, indeed, any mass at all, is transmitting quite a bit of information
In all the books I’ve read on quantum stuff I’ve never seen that claim made. It’s all about infinite mass and energy although I’m aware of it as weaseling about quantum tunneling.
And I don’t believe no information can be transmitted by QE. Just that by currently accepted theories it can’t.
I do believe that the universe is way weirder than we have any concept of and any iron clad laws we believe, such as the ‘light barrier’ will eventually be side-stepped.
Okay - I’m checking and Einstein said it too. Still think the universe is too weird to be pinned down like that though, mainly because it would be so boring.
And stuff like the Rochester experiment gives me hope.
Now where’s my DeLorean?
I don’t see how this follows. Just because some effect seems to happen before the seeming cause doesn’t mean that it did.
It’s just so tempting, isn’t it? Surely we ought to be able to make something of this – if one entangled quantum particle can tell the other ‘collapse now!’ instantly regardless of distance, then surely there’s a possibility for us to send a message via that channel, if we just try cleverly enough…
But actually, the reason that we can’t isn’t some deep and speculative quantum mechanical theorem, but rather simple logic – if each of two parties gets one part of an entangled quantum pair, that’s not in principle any different from two parties each getting a sealed envelope randomly stuffed with a card showing either a ‘0’ or a ‘1’, each of which only exists once (so that a ‘1’ in one envelope means there’s a ‘0’ in the other). Thus, if they both open their envelopes at some point, while they will instantly know what number is on the other’s card, there has been no information transfer – indeed, each of them can’t even know if the other is still alive, or has opened his envelope yet.
It’s the same with entangled particles, since you can’t pre-determine the outcome of any measurement – while your own measurement coming up ‘1’ for example instantly tells you that the measurement of the other party must come up ‘0’, there’s no way to actually instantaneously transfer information using that scheme; your measurement appears completely independent of anything going on on the other side – you can’t know if they’ve already measured or not, or if they’re all wiped out by an alien facehugger invasion, or have flown their spaceship into a black hole.
So isn’t this effectively using QE to transmit information?
FTL entails time travel, because of what’s called the relativity of simultaneity: as long as everything travels only at c or below, events in causal contact with each other appear in the same sequence in all frames of reference; if some influence is propagated faster than light, in some reference frames, they also move backwards in time, and thus, effects can precede their causes. Here’s some explanation of the whole thing.
It is. It’s also slower than light. 
(You have to transmit additional information over a classical channel in order to recover the transmitted quantum state.)
But … but … what if a wizard did it?
Okay - I’ve got nothin’.
Nothing but my faith in human ingenuity coupled with the unknown weirdness of the universe that is.
One day we’ll find all that we think we know is just a special sub-set of something totally off the wall. Only the other day I was reading in New Scientist how we’re all just holographic projections from the edge of the universe.
Which makes sense of a whole lot of things really. 
Yes. Here it is. I seem to remember a thread on it.
Our world may be one gigantic hologram
For the past seven years, this German set-up has been looking for gravitational waves - ripples in space-time thrown off by super-dense astronomical objects such as neutron stars and black holes. GEO600 has not detected any gravitational waves so far, but it might inadvertently have made the most important discovery in physics for half a century.
In a universe this weird just about anything is possible.
The Universe had a show where they struck a metal apple with a laser beam. The beam showed up in 4 different spots. They used it as a steppingstone to multiple universes. Not that there may be other unis but there has to be.
Then of course they are looking for other dimensions and hope the new particle accelerator will prove they exist. There is much weirdness left in science.
Wizards are rather unreliable for communication – they’re often old and cranky, hard of hearing, many have hidden agendas, and a surprisingly large portion for such a presumably complicated subject matter appear actually rather dim, so that I’d suppose that the fidelity of the transferred information is not significantly better than random noise (and worse, in some cases).
Yeah, here’s the other thread on it. Personally, I’m not too fond of the whole ‘hologram’ analogy, but by now it’s out there and we’ll have to deal with it.
The weirdness just means that different things than we’d think should be possible are possible, not necessarily more of them – a few quite reasonable things have turned out to be impossible, such as simultaneously knowing both momentum and location of an electron, or straightforward addition of (sufficiently great) velocities. 
Not with the Heisenberg Compensators engaged.
Or outside the Copenhagen Interpretation? Or if light turns out to be made of spaghettios?
Heck, relativity didn’t utterly destroy Newtonian mechanics: Newton is still useful for just about everything we do. It’s only when considering objects that are very massive or very fast that we have to add the extra v[sup]2[/sup] / c[sup]2[/sup] factor. Similarly, the existence of a superluminal will just mean some minor adjustment to applied physics, though theoretical physics might go nuts for a while.
That link doesn’t work for me, but I don’t buy it. If I place a transmitter at Proxima Centauri, then travel FTL to Earth in a day, I can with confidence say that in 4.3 years less a day that a signal will be received from Proxima Centauri.
But my OP makes no assumptions about the type or manner of superluminal event.
Quoth tagos:
As an excellent rule of thumb, whenever you read anything in the popular press about any supposedly faster-than-light experiment, your first assumption should be that the newspaper’s popular science writer got the details horribly confused and that the experiment in question doesn’t show anything remotely resembling what the article says that it does.
Actually, this is a pretty good rule of thumb for science articles in the popular press in general.