Well, this could change things (neutrinos)

[gorcee]

http://www.reuters.com/article/2011/09/ ... UU20110922

According to the article, researchers claim to have observed neutrinos moving at faster than light speeds.

The article is quite an understatement, so its veracity is certainly questionable. But, let's say that the journalism is accurate. The findings seem to come out of CERN, which is pretty reputable and puts a pretty tight lid on premature press releases. The article says the researchers have confirmed their findings, but are awaiting independent analysis. It doesn't go into much detail.

My question is, is the 60 ns discrepancy in a 730 km distance within the uncertainty threshhold of c?

[rflrob]

My question is, is the 60 ns discrepancy in a 730 km distance within the uncertainty threshhold of c?

My understanding is that the speed of light is defined to be exactly 299,792,458 m/s, and a second being a well defined, independent property, so the actual question should be "is it within the uncertainty threshold of 730km". I have not read (nor even attempted to skim) the paper, but I'm assuming if they've published it, they're clear of the error bars.

Personally, I'd guess that they've messed something up, and neutrinos move slower than light, but I don't have a clue what they might have done wrong.

[Macbi]

Almost certainly misreporting.

[Glass Fractal]

Almost certainly misreporting.

Well I can't seem to find CERN's statement on the matter but they have quotes from the scientists about it. More like easily excitable reporting.

[Tass]

My question is, is the 60 ns discrepancy in a 730 km distance within the uncertainty threshhold of c?

60ns is roughly equivalent to 60 feet. That is twenty meters. We can certainly measure distance much more accurately than that, over much greater distances than 730km. For comparison we can detect the moon moving away by centimeters by shooting lasers at it.

60ns is a lot when you are dealing with cutting edge, accurate, light speed including physics.

Still it is most likely a mistake. I couldn't find anything directly from CERN, but plenty of news stories. BBC has more info than the above linked, and apparently the scientists themselves think is a mistake, they just can't find it:

"we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy"

[Dopefish]

http://news.sciencemag.org/sciencenow/2 ... n-lig.html

This one goes into a bit more detail, apparently their uncertainty is 10ns. It seems most likely that theres some sort of systematic error and they're just throwing up their arms and saying that they can't find it, rather then saying that they actually are faster then light.

[Tass]

http://news.sciencemag.org/sciencenow/2011/09/neutrinos-travel-faster-than-lig.html

This one goes into a bit more detail, apparently their uncertainty is 10ns. It seems most likely that theres some sort of systematic error and they're just throwing up their arms and saying that they can't find it, rather then saying that they actually are faster then light.

Oh this post ninja'ed my edit above.

Yes apparently they have 10ns uncertianty because that is the accuracy of the GPS system* (3-4m).

*Sorry for spelling out the last part of an abbreviation, while leaving the letter for it as well, I hate it myself. PIN number, ATM machine, AFM microscope, HIV virus, bah.

[Sowieso]

http://io9.com/5842947/scientific-break ... than-light

^^Another article about it.
Apparently (according to BBC according to io9) they took 15,000 measurements, which I would say is a good way to assure accuracy. I'm no expert physicist but I plan on tuning in to this live seminar they're holding tomorrow (info in link).

How exciting!

[Glass Fractal]

Is it maybe a general relativity thing that they didn't account for? Gravity, the rotation of the planet and all that stuff? (just throwing that out there, supposedly GR ends up creating FTL stuff somehow)

[gorcee]

http://io9.com/5842947/scientific-breakthrough-physicists-at-cern-have-recorded-particles-moving-faster-than-light

^^Another article about it.
Apparently (according to BBC according to io9) they took 15,000 measurements, which I would say is a good way to assure accuracy. I'm no expert physicist but I plan on tuning in to this live seminar they're holding tomorrow (info in link).

How exciting!

That many measurements can also indicate a systematic error, which I admit seems to be the most likely scenario.

I'd love to see the data. I wonder if it's some or all of the neutrinos coming in 60ns too soon.

[Sheikh al-Majaneen]

What is the likelihood that it was just a random cosmic neutrino in the right place and time? (obviously, IANAS)

[Glass Fractal]

What is the likelihood that it was just a random cosmic neutrino in the right place and time? (obviously, IANAS)

It would have to be 15,000 random neutrinos in exactly the right place and time. The odds of that are nil.

[gmalivuk]

supposedly GR ends up creating FTL stuff somehow

No it doesn't.

But yeah, this is a sign of their actually being real scientists: rather than claiming they've disproved all of physics, they're earnestly requesting help from the rest of the scientific community in figuring out where mistakes or errors crept in.

[Diadem]

supposedly GR ends up creating FTL stuff somehow

No it doesn't.

But yeah, this is a sign of their actually being real scientists: rather than claiming they've disproved all of physics, they're earnestly requesting help from the rest of the scientific community in figuring out where mistakes or errors crept in.

I betcha they are still secretly hoping to have disproved all of physics. But they certainly seem to be doing things the right way around. First try to figure out an explanation for yourself, if that fails ask for help, without making bold claims.

If true (which I do not believe for a second) it'll take at least 2 decades of independent verification, more accurate measurements and dozens of experiments to rule out alternative explanations before it'll become accepted within the general community. A more likely and almost equally interesting possiblity though is some other as of yet unknown phenomenon. Though the smart money is of course on 'systematic error'.

[astrosteve]

Maybe my college professor was wrong, maybe I'm misremembering since this was in 1995 (and I'm not a physics major), but I always understood Relativity allows for faster than light particles.

Relativity, I was taught, was a barrier, not a universal speed limit. If something comes into existence moving below the speed of light, it can't ever get to light speed or above. However, if a particle comes into existence moving above light speed, it's stuck there. It can never move slower than light. The only way this discovery would be a problem would be if neutrinos are accelerating past the speed of light.

Also, doesn't Cherenkov radiation move faster than light?

As I said, this was a long time ago but for years I've been assuming they'd eventually find particles that move faster than light.

[Carnildo]

Maybe my college professor was wrong, maybe I'm misremembering since this was in 1995 (and I'm not a physics major), but I always understood Relativity allows for faster than light particles.

They're called Tachyons. Although tachyonic behavior is a possible solution to the equations of General Relativity, such particles are generally considered to not exist.

Also, doesn't Cherenkov radiation move faster than light?

Cherenkov radiation is the result of a particle moving faster than the speed of light in its local medium, but no faster than the speed of light in a vacuum.

[++$_]

They KNOW they haven't disproved physics.

In SN1987A, a pulse of neutrinos arrived several hours before the light was detected. SN1987A is located 168,000 light years from Earth. If neutrinos travel at 40,001c/40,000, then the neutrinos from SN1987A should have arrived 4 years before they did.

[Glass Fractal]

supposedly GR ends up creating FTL stuff somehow

No it doesn't.

I always hear people bring up stuff about non-inertial reference frames? I assume it's some kind of illusion or virtual speed.

Relativity, I was taught, was a barrier, not a universal speed limit. If something comes into existence moving below the speed of light, it can't ever get to light speed or above. However, if a particle comes into existence moving above light speed, it's stuck there. It can never move slower than light. The only way this discovery would be a problem would be if neutrinos are accelerating past the speed of light.

It happens to be both a limit and a barrier (in the senses you're using the words).
You can't accelerate an object above the speed of light because you needs infinite energy to do that.
However you also get problem if you just happen to start above the speed of light. You break causality.

The way it was explained to me was with duelists:

Alice and Bob have tachyon guns.
They agree to count to eight then turn and shoot.
They fly away from each other at 86% the speed of light, which means that they move through time at half speed relative to each other.
Alice counts to eight then turns and shoots.
Her shot reaches Bob instantly because it's a tachyon bullet but Bob has been going at half speed so it hits him as he reaches the count of four.
Bob immediately turns to retaliate and shoots back with his tachyon, killing Alice.
But Alice has also been going at half speed so the bullet hits her as she reaches the count of two, killing her several seconds before she can fire the shot that started the whole thing.

Or something like that? (also not a physicist)

[eSOANEM]

Possibly a bigger problem with tachyons is the gravitational cherenkov radiation caused by them travelling faster than their gravitational wave (c) and rob them of energy. As they are tachyons, losing energy accelerates them and so any tachyon would necessarily accelerate towards infinte velocity and zero energy.

[sourmìlk]

So if we can send messages back in time. What happens if I tell a computer to send a boolean value to itself three minutes ago, at which point the computer saves the value and sends the opposite one back three minutes later?

[Darrell88]

Thought it was from a school lab, but if it's from the CERN then there's a high chance it could be true. But I really hope that they made a mistake cos it could bring down 100 years of physics ....

[Diadem]

Thought it was from a school lab, but if it's from the CERN then there's a high chance it could be true. But I really hope that they made a mistake cos it could bring down 100 years of physics ....

Could what be true? Even the authors of the paper are not suggestion a violation of causality. They are presenting it as an unexplained phenomenom they want opinions on.

[curtis95112]

So if we can send messages back in time. What happens if I tell a computer to send a boolean value to itself three minutes ago, at which point the computer saves the value and sends the opposite one back three minutes later?

Either the universe splits in half or your computer can't run that program for some reason.

If it turns out the universe is consistent despite causality being broken, we get to solve NP problems in polynomial time.

[sourmìlk]

So if we can send messages back in time. What happens if I tell a computer to send a boolean value to itself three minutes ago, at which point the computer saves the value and sends the opposite one back three minutes later?

Either the universe splits in half or your computer can't run that program for some reason.

If it turns out the universe is consistent despite causality being broken, we get to solve NP problems in polynomial time.

What do you mean by "splits in half?" And as an observer just watching the computer, what value do I see when I say "cout <<futureBool ? 'true' : 'false';"

[ArgonV]

Say this wasn't just a measuring mistake, could this then be a bit of proof for Tesla's aether-theories? Or are those just a bunch of bull?

[Thesh]

If I was going to speculate wildly, I'd say they created a wormhole.

[Minerva]

The actual paper from the CNGS team is here: "Measurement of the neutrino velocity with the OPERA detector in the CNGS beam"
http://arxiv.org/pdf/1109.4897v1

At the moment all the usual arXiv disclaimers apply. Not published for peer-review.

[idobox]

Thought it was from a school lab, but if it's from the CERN then there's a high chance it could be true. But I really hope that they made a mistake cos it could bring down 100 years of physics ....

I wish, although I don't really believe, they didn't make any mistakes.
Science goes forward when we encounter unpredicted phenomenons.

The way they estimate the emission time of neutrinos is quite indirect. It seems very likely to me, who don't really understand particle physics, that a small error in the proton velocity inside the graphite target, proton/graphite collision rate, or speed of resulting pions could easily result in a 60ns error.

[makc]

What happens if I tell a computer to send a boolean value to itself three minutes ago, at which point the computer saves the value and sends the opposite one back three minutes later?

Assuming by that time computer already received 'false', it will send 'true', problem? *trollface* Your computer does not explode Why woud it - I mean we received 'false', ok - so you're left with investigating the reason behind your system failure (exactly why you received 'false' after you sent 'true' is not really important).

edit: better question is, what happens when you start the program? does it just sit there in the infinite loop, waiting for the signal, until the conditions are such that nothing in the universe can prevent it from sending the signal back? or, if the universe allows it to receive the signal that was (or will be) never sent, - does it receive tons of random signals?

[thoughtfully]

I think this article may have the information you're looking for.

[sourmìlk]

Yes, except I would receive false, send true, receive true, send false, etc. It's in a continuous cycle of receiving the opposite of what it sends, and sending the opposite of what it receives. So if I tell it to print the value of the boolean it received, what will it display? It won't just display "false", because then it well send true and will have displayed "true", which means it will send "false" and will have displayed "false" etc.

EDIT: okay, so I get that the state of the boolean is a superposition of true and false. I'm still not sure what that means when I say print(boolean);

[makc]

It's in a continuous cycle

it is not cycle. It is just two events.

[sourmìlk]

It's in a continuous cycle

it is not cycle. It is just two events.

Two contradictory ones. That each cause another in turn. I don't know if it's physically a cycle, but I thought that it was a nice visual sort of representation of the chain of causality.

[makc]

Two contradictory ones.

I dont know where is the contradiction that you are seing. Without repeating my 1st post in this thread, there is nothing much else I can comment. You receive the value 1. You then send some other value 2. Which means (after you sent value 2) that something happened to your signal on its way back. You know it did, because you already received value 1. There is no problem. Unless you insist that nothing happens to your signal (like, "it is my thought experiment, so I can do whatever the hell I want"), but then you are trying to force us to accept two contradictory premises, which is not reasonable. It's like if I would simply say "imagine I have a cake, and I don't", but in more complex way. Not a paradox, just nonsense

[curtis95112]

So if we can send messages back in time. What happens if I tell a computer to send a boolean value to itself three minutes ago, at which point the computer saves the value and sends the opposite one back three minutes later?

Either the universe splits in half or your computer can't run that program for some reason.

If it turns out the universe is consistent despite causality being broken, we get to solve NP problems in polynomial time.

What do you mean by "splits in half?" And as an observer just watching the computer, what value do I see when I say "cout <<futureBool ? 'true' : 'false';"

By that I meant every time you send information back to the past, you send it to a parallel universe that's not really your own. So you may receive "True", and send "False, and it's perfectly consistent. More likely (insofar as any of this is likely), you'll find that quantum uncertainty caused your computer to malfunction because the probability of it functioning was zero. Or so says Novikov, http://en.wikipedia.org/wiki/Novikov_self-consistency_principle

[sourmìlk]

Two contradictory ones.

I dont know where is the contradiction that you are seing. Without repeating my 1st post in this thread, there is nothing much else I can comment. You receive the value 1. You then send some other value 2. Which means (after you sent value 2) that something happened to your signal on its way back. You know it did, because you already received value 1. There is no problem.

Well yes, there is, because I then send back the value 1, which causes me to send back the value 2, which causes me to send back the value 1.

And curtis: if I can send information back in time, how is the probability of me doing it this way 0? Is it proof that sending information back in time is impossible? Or is it that, in all possible universes, quantum fluctuations will always cause it so my computer breaks and can't run the program properly?

[makc]

yes, there is, because...

...you're hopeless.

[sourmìlk]

I don't think I understood what you were saying then. What, for example, could have happened to the signal? I sent a 2 and received a 1. Assuming things work perfectly, isn't that a contradiction? And if they don't work perfectly, why not?

[OllieGarkey]

Are you all stodgy old men in ivory towers puffing on pipes?!

We have a truly fantastic, truly crazy result from what is the most advanced physics laboratory on earth, and your reaction is the biggest "Meh" I've ever seen.

No one's even remotely excited about the possibility of faster than light interstellar travel? Not even remotely?

Do you guys just love rules and constraints?

I know jumping to conclusions is idiotic, but can't you people just consider how cool this is and what it might mean rather than getting upset that your rules might be broken?

Are you all so Autistic that you hate changes that might mean something incredible for the human species?

Because if we can send mass PAST the speed of light, FTL travel becomes a question of Engineering.

Is it that you don't want to share your little corner of the universe with engineers?

Why would it be so bad if we had to re-write physics again? I thought scientists loved challenges like this, but you whinging sadsacks are so sure that this result is some kind of lab error.

Think about it:

If they made an error, their careers are probably over. Do you honestly think they wouldn't check and recheck everything, ever equation, every instrument, every line of code to make damned sure there wasn't a career-ending error somewhere before they published their paper?

These aren't glory hounds! They're not saying "We broke physics!" They're saying "Holy crap, we didn't expect this. Hey everybody: help!"

And you're all standing around talking about how wrong their result was rather than thinking about what might be the case, and what the new model might be?

An inconstant speed of light, for example.

But no, you people have no imagination, no joy in the idea that there are mysteries yet to be unlocked by human science, and you take yourselves way too fucking seriously.

Collectively, you're the biggest disappointment since the crucifixion.

[cpt]

Subtle trolling