"If we do not have causality, we are buggered"...

[Guest]

http://www.guardian.co.uk/science/2011/sep/22/faster-than-light-particles-neutrinos

[The Nal]

Faster than the speed of light!? Time travel?! wow.

I've always said that Einstein was an awful wally.

http://www.youtube.com/watch?v=GrsN8iTwFiw

[eFestivals]

the thing I don't get about this is how exactly they're able to know that the starting point and end point are both working from the same point in time to then be able to measure the time taken for the neutrinos to travel.

As far as I'm able to see, there's absolutely no way of knowing that both points are synched to the same point in time. Anything that might be used to measure that they're in synch is subject to time delays, and those time delays that will always have a different variance each time its tried, as conditions will never be 100% identical.

I guess that these tefal-heads believe they've got a way of getting those points in synch, so I'd love to know how.

[eFestivals]

Faster than the speed of light!? Time travel?! wow.

you do know that even Einstein's theories allow time travel to happen without going past the speed of light, don't you?

Or put more correctly, that's the perception a person travelling at near-light speed would have in relation to those who weren't travelling at near-light speed.

[eFestivals]

they fire the particles at a given time, and they arrive earlier than they would if they were travelling at the speed of light....

< shrug shoulders >

(like I understand....)

yeah, but to know they arrive early, they have to ensure that the send point and the receive point are measuring from the same point in time. As I said, I can't see how they can know that (I'm not saying it's impossible, I'm saying I don't get how they can do it).

If the test was done to bounce the signal off something and come back to the send point then that problem goes away, but according to that article that's not how they've done it (but if they had done then that's a method that has its own different problems).

[5co77ie]

I pity A Level Physics students.

When I was doing Physics they realised the theories on particle physics (higgs boson) and dark matter (cold dark matter/exotic mesons) we were learning were wrong - however our course refused to acknowledge this and we had to learn what had become out dated theories - I refused to answer the questions pertaining to these with the wrong answers put about the new findings and got marked zero each time.

It totally put me off science.

[feral chile]

I pity A Level Physics students.

When I was doing Physics they realised the theories on particle physics (higgs boson) and dark matter (cold dark matter/exotic mesons) we were learning were wrong - however our course refused to acknowledge this and we had to learn what had become out dated theories - I refused to answer the questions pertaining to these with the wrong answers put about the new findings and got marked zero each time.

It totally put me off science.

[eFestivals]

The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery."

from http://www.bbc.co.uk/news/science-environment-15017484

they can measure it as many times as they like, but without a method to ensure that the start and end point are working from the exact same point in time, there can be no meaningful statistical significance as there's no fixed reference point to take a measure from, especially when we're talking about billionths of a second.

So I'd love to know how they've synched up both the send and receive points. I'm presuming they have done somehow; I can't believe they've been dumb enough to only use an average.

[eFestivals]

Yeah same thing happened to me as a student of psychology. We tried to replicate an experiment and failed to obtain the same results, and we had to make up reasons why our experiment failed, because we couldn't contradict established researchers.

That makes a mockery of the principle of replicability though, if all our variables were the same, which as far as we could tell, they were.

the problem there is that, despite it's claims, psychology is not a science. It's instead an idea with only human ideas of how we think and operate as its basis, with nothing to give any external verification for those ideas.

[The Nal]

Oh look... More "laws of science" being made to look silly

[The Nal]

Can you prove that

[rabid]

So I'd love to know how they've synched up both the send and receive points.

[eFestivals]

Well duh, Timestamps in UDP packets obviously.

If that was correct and it worked, they'd already have known they could break the speed of light before doing the experiment.

It ain't right. It's not something that's possible without knowing the always-fixed time (and such things don't travel in always-the-same-time) it takes for that packet to travel from a to b ... and it would still need a fixed reference point-in-time, which they don't have.

[rabid]

It ain't right. It's not something that's possible without knowing the always-fixed time (and such things don't travel in always-the-same-time) it takes for that packet to travel from a to b ... and it would still need a fixed reference point-in-time, which they don't have.

[eFestivals]

this is where your little brain fails... There isn't any evidence to prove something exists over god... God and the big bang for example mix together quite well... One does not destroy the other...

And this is where your little brain fails.

While one does not destroy the other, there is no evidence for one and only internal verification, while the other has a heap of externally verified evidence to support it.

So while one does not destroy the other, one is baseless while the other is not. They are not equal ideas.

[Pinhead]

"they can measure it as many times as they like, but without a method to ensure that the start and end point are working from the exact same point in time, there can be no meaningful statistical significance as there's no fixed reference point to take a measure from, especially when we're talking about billionths of a second.

So I'd love to know how they've synched up both the send and receive points. I'm presuming they have done somehow; I can't believe they've been dumb enough to only use an average.

they can measure it as many times as they like, but without a method to ensure that the start and end point are working from the exact same point in time, there can be no meaningful statistical significance as there's no fixed reference point to take a measure from, especially when we're talking about billionths of a second.

So I'd love to know how they've synched up both the send and receive points. I'm presuming they have done somehow; I can't believe they've been dumb enough to only use an average."

Can't they just factor in the known, measurable difference in time that is expected between the two points so as to exclude that from the calculation of neutrino speed? It will be small in any case as the diameter of the planet does not represent a very significant distance for significant dilations in time to occur.

[eFestivals]

The timestamp in the datagram is the reference.

it only works if the receive point is synched up somehow beforehand (possible to do if in close proximity, impossible if not), or if the travel time for the packet is 100% fixed (it never is - it goes thru too many devices, each with their own issues) so that you can add the travel time to the timestamp.

You could reasonably ignore these factors over an average if looking to see a large-ish time difference, but I don't see how they can be ignored when you're coming out with a result to billionths of a second.

[eFestivals]

Can't they just factor in the known, measurable difference in time that is expected between the two points so as to exclude that from the calculation of neutrino speed? It will be small in any case as the diameter of the planet does not represent a very significant distance for significant dilations in time to occur.

They can know how quickly the neutrinos are meant to travel, that's an easy part to this ('easy' meant in a relative way).

But to take a measure of how quickly it's got from A to B, A and B need to work from the same reference point in time, they need to be synched.

Any method I can think of for synching them has its own time delays &/or varying conditions, meaning that getting an absolute precise synch isn't possible.

As I've already said, this wouldn't much matter if the time measure result was fairly sizable, but for such a small time difference as they're reporting to have got, it seems to me to be of big relevance.

[eFestivals]

I thought the recieve point was the same place for the nutrinos and the 'light'. Why do they need to be synched up?

To measure how long something takes to travel from A to B requires a single reference point.

For you on a car journey from A to B, you can take your single reference point with you (your watch, say). But if you relied on your watch at A and someone else's watch at B, you can't be sure that the measure is right unless those watches are 100% in synch.

You could synch that other person's watch with yours on your arrival and then take the measure from their watch - but the accuracy of that measure is dependant on your watch having kept perfect time during the journey, something you can't know it has without referring back to the perfect time source that you set your watch against before you left (which is subject to a possible difference, because of the time taken to return your watch to A to make that comparison).

You could synch those watches by (say) telephone before you started your journey. But there's a delay to the telephone network so that B hears 'now' a fraction after you've said it (so they're not actually in synch), and that delay will always vary slightly because of changing conditions around the wires the signal travels along, and because of changing conditions with switchgear on the phone network

Hopefully that's made the issue I'm getting at a little clearer for you.

I'm not saying they can't do it, I'm saying that I can't think how they do it. All of the ideas I can think of have flaws, and flaws that always have variance because of changing conditions.

Edited September 23, 2011 by eFestivals

[rabid]

it only works if the receive point is synched up somehow beforehand (possible to do if in close proximity, impossible if not), or if the travel time for the packet is 100% fixed (it never is - it goes thru too many devices, each with their own issues) so that you can add the travel time to the timestamp.

You could reasonably ignore these factors over an average if looking to see a large-ish time difference, but I don't see how they can be ignored when you're coming out with a result to billionths of a second.

[rabid]

maybe the nutrinos know a short cut?

[5co77ie]

As has been suggested, they may be passing through other dimensions. They could save a bit of time by disappearing from this one and immediately reappearing 100km further on.

[Pinhead]

The inter-dimensional theory seems good in the sense that neutrinos seem to behave as if they live outside of our space/time, possibly indicated by the observation that they do not respect the currently defined boundaries of velocity as imposed by the photon. In which case measuring them would be rather a waste of effort in itself since how can you measure anything that lives outside thouse boundaries. Step forward please Prof. Brian Cox, particle physicist and keyboard player . . .

[The Nal]

Maybe it was god playing games ?

[Pinhead]

Only just noticed this follow up article . . .

http://www.bbc.co.uk/news/science-environment-15034414