Rumraket wrote:

GrahamH wrote:How do they measure time interval and distance between Cern and Gran Sasso (~732 kM) to the accuracy needed to identify a 60ns discrepancy?

Syncronized atomic clocks I presume.

Yes. I heard a scientist on the radio raising the issue that the synchronisation of the clocks could be a possible route to error. I'm sure the Opera team would have checked this several times though.

GrahamH wrote:

Jim Al-Khalili, a physicist from the University of Surrey wrote:Let us be clear: it would be a tremendously exciting time for physics, and a daunting one for physicists, but it is not going to change the price of milk.

Perhaps the most exciting thing is that time travel would look more feasible.

Why would FTL neutrinos make time travel more likely?

anything FTL if the right parts of relativity still retained validity given such a thing would permit sending at least information back in time.

A thought occured to me when i read this article... Does this explain why the universe seems to be expanding faster than we think it should?

Just a thought.

Whoa...

Thing is, this could simply be some unknown tunnelling effect, or a function of the dimensional manifold, about which we know little, or even a function of quantum uncertainty. Exciting stuff, to be sure, but there are possible explanations that don't overthrow special relativity.

james1v wrote:A thought occured to me when i read this article... Does this explain why the universe seems to be expanding faster than we think it should?

Is it? I know that observations have shown that expansion is accelerating, but current models map the expansion well enough, and I can't think of a connection between this and that anyway. That's not to say that there isn't one, of course.

hackenslash wrote:Thing is, this could simply be some unknown tunnelling effect, or a function of the dimensional manifold, about which we know little, or even a function of quantum uncertainty. Exciting stuff, to be sure, but there are possible explanations that don't overthrow special relativity.

Could it be that this observation is related to the difficulty physicists have in combining general relativity with quantum mechanics? I mean, like it's at the cutting edge between GR and QM. sort of.. I hope you get what I mean..

JoeB wrote:

hackenslash wrote:Thing is, this could simply be some unknown tunnelling effect, or a function of the dimensional manifold, about which we know little, or even a function of quantum uncertainty. Exciting stuff, to be sure, but there are possible explanations that don't overthrow special relativity.

Could you expand on that, Hackenslash? What is the dimensional manifold?

I'm not sure if this was already posted, but here's the paper at

http://arxiv.org/abs/1109.4897


My bet is on a technical glitch

JoeB wrote:

hackenslash wrote:Thing is, this could simply be some unknown tunnelling effect, or a function of the dimensional manifold, about which we know little, or even a function of quantum uncertainty. Exciting stuff, to be sure, but there are possible explanations that don't overthrow special relativity.

Could it be that this observation is related to the difficulty physicists have in combining general relativity with quantum mechanics? I mean, like it's at the cutting edge between GR and QM. sort of.. I hope you get what I mean..

Certainly, yes. If M-Theory has any basis in reality, this could cheerfully be explained in that framework. I'll come to why in a moment.

Denny wrote:Could you expand on that, Hackenslash? What is the dimensional manifold?

A manifold is a collection of multiple parts. In this case, we're talking about the totality of all dimensions, seen and unseen, hence the 'dimensional manifold'. We could really call it spacetime, because that's what it is, however many dimensions there are, but I use the term simply to differentiate between the common conception of spacetime, i.e. the 3 dimensions of space plus 1 of time, and the totality of all dimensions.

If M-Theory is correct, there are 11 dimensions in total (although it is still possible that this figure could be revised as the solutions are refined, but the solutions thus far found, using a perturbative approach, suggest that 11 is where it's at), the 4 we experience, plus 7 more. The idea is that these 7 dimensions are tacked on to every point of our familiar spacetime, but curled up really small (in the region of the Planck length, or 1.616x10-35 metres, although possibly somewhat larger). That being the case, this could possibly be explained by the muon neutrino taking a little hop through another dimension, which would mean that it wasn't travelling through our familiar spacetime for at least a portion of the time, which could easily explain the result without violating SR, because SR tells us that the limit holds for spacetime.

For those who will undoubtedly jump in and say that all of this is speculative, untestable nonsense, there is a test that can be carried out, at least in principle, to verify the existence of extra dimensions, although the test would require that the hidden dimensions are curled. More on that HERE.

As for the latter, if we take the path-integral formulation of quantum mechanics as our guide for the purposes of this exercise, as postulated by Feyman, we see that particles are treated as existing at every point on all possible paths simultaneously until an observation is made, collapsing the wavefunction. Once the observation has been made, the particle returns to its state of superposition, which could mean that it can jump from here to there without actually passing any point in between. This would seem to violate causality, but causality is intact, because no information can be transmitted this way (which should answer some of the above objections, to boot).


Coming back to the original question by Joe, the solution to the unification of GR and QM (note that, although we're talking about SR here, not GR, GR essentially supersedes SR, as SR is simply a specialised case of GR) proposed by M-Theory is the graviton (not a prediction of M-Theory, but of quantum field theory) which, like all other particles, are merely vibrating strings (the vibrations are the source of energy and therefore mass via E=mc2), which means that all particles, including this postulated boson, come under the same framework.

Note: As always, this is massively oversimplified but not, I think, to the point of being misleading. No doubt some fo the physics geeks will weigh in if I've cocked anything up.

A good source for this material, quite accessible, is The Elegant Universe by Brian Greene.

Who's there? Neutrinos. Knock Knock



sorry, couldn't help it

Thanks! That was a great explanation.

Not that good, I think. There are some problems with it. Let me see if I can iron them out and make it a bit more robust.

The seminar from CERN today 2hrs long.
http://www.youtube.com/watch?v=ZFz3fJMJ-yA

Rumraket wrote:

GrahamH wrote:How do they measure time interval and distance between Cern and Gran Sasso (~732 kM) to the accuracy needed to identify a 60ns discrepancy?

Syncronized atomic clocks I presume.

something like that...


The distance between terrestrial points far apart can be measured very precisely with VLBI:

VLBI is most well known for imaging distant cosmic radio sources, spacecraft tracking, and for applications in astrometry. However, since the VLBI technique measures the time differences between the arrival of radio waves at separate antennas, it can also be used "in reverse" to perform earth rotation studies, map movements of tectonic plates very precisely (within millimetres), and perform other types of geodesy. Using VLBI in this manner requires large numbers of time difference measurements from distant sources (such as quasars) observed with a global network of antennas over a period of time.

http://en.wikipedia.org/wiki/Very_Long_ ... rferometry

In this case, Dual Frequency static GPS in long occupation times (SV geometry change) measuring the route above ground, and lines parallel to the route of the timing track. Observed eccentricities in the distance between parallel lines can discriminate local anisotropies in spacetime, ie gravity.

Combined with some intense absolute and relative Gravimetry of the route.



As for timekeeping/sync, 60ns of latency is pretty coarse. 1ns is everyday stuff...

National standards agencies maintain an accuracy of 10−9 seconds per day (approximately 1 part in 1014), and a precision set by the radio transmitter pumping the maser. These clocks collectively define a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but approximately synchronized, by using leap seconds, to UT1, which is based on actual rotations of the earth with respect to the solar time.

http://en.wikipedia.org/wiki/Atomic_clock

Brian Cox talks about it here http://www.bbc.co.uk/programmes/b014vy08

Animavore wrote:Brian Cox talks about it here http://www.bbc.co.uk/programmes/b014vy08

"Not available in your area". Bah

That sucks. There are work arounds though

http://www.daveproxy.co.uk/

Rumraket wrote:

Animavore wrote:Brian Cox talks about it here http://www.bbc.co.uk/programmes/b014vy08

"Not available in your area". Bah

Here's the link to the podcast. VLC might handle it without a proxy.

http://www.bbc.co.uk/iplayer/console/b014vy08

(Try Opera Turbo too)

Oh yeah, it starts at 2:17:00

Oh joy! He's making a new series for the BBC called The Wonders of Life about abiogenesis, evolution... etc.