Just like a speeding driver...
...they've been caught breaking the speed limit once and now they're being careful for a bit. Perhaps they're running out of points on their license or can't afford the increased insurance premiums.
Just in case there was any doubt that our current understanding of physics remains unimpeached, those OPERA boffins probably definitely didn't prove that neutrinos can go faster than the speed of light. More boffins, this time involved in the ICARUS experiment between CERN and the Gran Sasso lab in Italy, reported a new …
"A finding that would interfere with the widely accepted maxim derived from Einstein's theory of general relativity that nothing can travel faster than light"
Would that rather be:
"A finding that would be inconsistent with the widely accepted axiom at the basis of Einstein's theory of special relativity that a maximal speed exists, which is the same in all non-accelerated reference frames, and which is equal to the speed of light, an excellent idea which was already pretty much apparent in Maxwell's equations and closely orbited by Lorentz and Poincaré."
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The beauty of the original news last year was that it revealed the profound ignorance of the Italian minister / Berlusconi-lassGelmini - who after expressing initial surprise added that she was v.proud that Italian research had constructed the necessary tunnel from CERN all the way to to Gran Sasso in Italy!
On the other hand it's only dense rock because most matter interacts well with it as does light - neutrinos don't which is why the ICARUS experiment used 600 tonnes of liquid argon in an attempt to detect a tiny percentage of the beam and why the many billions per cm^2 that arrive from the sun every second don't pose a significant biological risk. ( although anyone that is worried about that needs to wear a VERY thick tinfoil hat)
"why do they not have a huge energy/mass???"
We don't know how fast they are going or their exact mass but their energy will fit the SR equations - they will not be traveling at the speed of light but they could be close enough to make measuring the difference pretty difficult
"Maybe only a very little bit slower, but shouldn't it be measurable"
Depends on the accuracy they can measure to - the time differences could be REALLY small
a) The mass in not known but is expected to be real but very small and therefore it cannot actually reach c although it may get very close and the closer it gets the higher its energy.
b) The neutrino (which needs to have a certain minimum energy) needs to 'hit a proton head-on" which generates a neutron and a positron. The positron then combines with an electron and generates two photons. Some detectors have relied on detecting the pairs of photos but the argon, I think, acts as a bubble chamber detecting the energetic charged positron before it is destroyed.
That whenever you see a small effect in one experiment, you still know nothing. What you need are many experiments (or studies) preferably combined via linear regression.
Essentially what you do there is to find a numeric way to quantify the effect. For example, in this case, the difference to the speed of light, divided by the speed of light. Then you make a graph, showing the quantified effect over the size of the study. In reality small studies should be more random than larger ones, however studies with negative or no effects are less likely to be published, this is called the publication bias. What you will see is that the larger the study is, the smaller your effect will be. You can now lay a straight line through your dataset, and will find you that it'll point towards the true value. If there actually an effect it would point towards it, if there is no effect, it'll just point straight upwards to no effect or point towards "negative" effects.
If something goes faster than light, then there's some frame of reference where it travels backwards in time.
It's only theoretical - you would have to be travelling past at very nearly the speed of light yourself to see it.
But all reference frames are equally valid - it's special relativity, not even general.
Because of time dilation. If you fly across the Atlantic on Concorde, or a similarly fast plane, there is a small but measurable difference between the time you spend on the plane, and the time someone on the ground would spend watching you on the plane. You would come of the plane a couple of nanoseconds younger than you would have been had you stayed on the ground, If you flew at the speed of light, you would spend no time at all on the plane, but to someone on the ground, it would take you about 19ms to get there. If your plane went faster than light, then you would experience time going backwards on the plane, while on the ground, it would take less than 19ms.
Well, the result is a gaussian around zero:
The neutrinos have average energy of 3 GeV (unsure). This is enormous (solar neutrinos are < 18 MeV), the neutrino rest mass is < 0.10 eV/c², so I think no-one actually bothers to make a difference between v_nu and c.
I wonder if this result will be splashed across the news broadcasts as much as the initial result was? I doubt it will even get a "and finally..." mention, leaving the masses believing that Einstein was wrong, science is wrong and that we should all believe in the religionist claptrap that the anti-science establishment have been vomiting all along...
Where do you live? I live on mainland Europe and I can tell you that the practical convenience of the Euro is one of the best things that has happened recently (for certain values of recently).
I used to have lots of different currencies in my pocket and I'd have to pay to get them exchanged from one to the other. Having one currency has made my life much easier/better, which is what the politicians are actually supposed to enable. (They don't, they're shithouses but...)
Now, if you want to complain about how the EU lands broke their own rules on it's introduction (Denmark voted against it and that should have been an end and yet, as predicted, the bigger countries ran roughshod over them), or perhaps how the EU lands broke their own rules on deficits before the latest "pact" (*cough* France, Germany, The Netherlands *cough* - what, you don't get the same news we get? hmmm...) , or possibly how certain USA banks cooked various books and lied about certain countries' fiscal status (which is the main problem at the moment to be honest)...
...if you want to complain about that, then you might have a point
Not withstanding that being a member of the Euro club would mean that we would be required to hand over fiscal control of UK economics to unelected buerocrats. I never agreed to us joining the EEC so that we would have fiscal as well as trading union.
Our ancestors gave their lives to prevent this country falling into the clutches of bad people from abroad, and here we are arguing to hand over that same power. And one of the major players in that arrangement is Germany. I have more respect for my forefathers and consider it a shame that so many people within the UK seem committed to handing over what they fought to protect.
Of course the Euro has certain advantages as you rightly suggest. However, just because it happens to be convenient for you with respect to managing different currencies does not mean that it should apply to folks back home. As for me, when I'm travelling abroad I tend to pay by credit card - and I really couldn't give a t0ss which currency I am buying in. Having a few Francs, Deutschmarks and so on in my wallet never inconvenienced me to the point where I was willing to give up the UK controlling its own currency.
What is the momentum of the neutrinos at the newly measured speed? If, as said, they arrived at the speed of light (to within experimental error) their momentum is infinite (within experimental error). Since the detector did not explode, either the neutrino was not traveling at the speed of light, or the neutrino did not change speed, and therefore was not detected.
I could probably find the answer to this by Googling but thought i'd ask here and make myself look stupid.
What kind of light travels at the speed of light? i mean, there are different wavelengths right?
Infrared-visible light spectrum-ultraviolet. Do they all travel at the same speed but only go different distances??
All light frequencies travel at the same speed in a vacuum. When passing through a non-vacuum medium higher frequency photons travel faster than lower frequency photons, both travelling slower than if they were travelling through a vacuum. The amount they are slower is a function of their frequency and a characteristic of the medium. The "thicker" the medium and the lower the frequency, the more slower than vacuum light speed they travel at. That's how you get rainbows!
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