/sci/ - Science & Math

Either measurement error or they were always moving faster, meaning you still can't accelerate something past the speed of light

>>3872720
>or they were always moving faster
How is that possible?

http://arxiv.org/abs/1109.4897
http://indico.cern.ch/conferenceDisplay.py?confId=155620
http://arxiv.org/abs/1109.6160
http://arxiv.org/abs/1110.0239
http://arxiv.org/abs/1109.6562
http://arxiv.org/abs/1110.0241
http://arxiv.org/abs/1110.0736

>>3872720
>>3872720
Neither of your statements are supported by evidence. Faggot.

Neutrinos can go FTL. The experiments were repeated 1600 times over 3 months. Neutrinos have mass. Therefore, at least the "no FTL" aspect of relativity is debunked.

Deal with it, fundamentalist.

>>3872741
Aliens you fool

Its always aliens

>>3872747
[Citation needed]

>>3872753

>>3872747
Or there is a systematic error in their experiment they haven't managed to figure out.

>>3872762
Don't be foolish, Picard.

>>3872753
>Citation needed
here ya go.

>>3872747
>repeated 1600 times
Nothing was repeated 1600 times. There were 16000 neutrinos, but most of them were irrelevant for the analysis, and since the analysis compared PDFs, no single neutrino could have been enough to measure the speed. Even if there were 1600 measurements, which there were not, that wouldn't eliminate systematic errors. Now as you can see if you read the paper, there were a lot of cross-checks on the timing and distances, but there is still room for systematic error especially on the shapes of the PDFs. There's been criticism of the synchronization, too, although I don't know yet how valid the criticism is.

Other measurements of neutrino velocity conflict with the measurement, and although of course there are ways to reconcile them, the more complicated you have to make a theory, the more likely it is wrong.

The speed of light isn't the same as the causality speed limit.
They just found out that neutrinos travels faster than some types of light.

OP here. So basically, they still don't know what they're looking at?

>>3872735
What the fuck am I reading?

>>3872795

what makes you say that?

>>3872812
read
>>3872735

>>3872810
Science isn't good at providing instant gratification. Ask again in a year or two.

>>3872810
They know exactly what happened, but there is nothing exceptional about it.
It's made as a sensational subject by the media because it's commonly believed that the speed of light equals the causality speed limit, which it does not.
Blame it on the poor physics education in schools.
Speed of light =/= c = fastest possible speed.
Causality speed limit = c = fastest possible speed.

>>3872829
The speed of light is still c within measurement error, and the neutrino thing, if correct, doesn't change that. There are very stringent upper bounds on the photon mass.

>>3872851
>The speed of light is still c within measurement error, and the neutrino thing, if correct, doesn't change that. There are very stringent upper bounds on the photon mass.
Correct. But, it's important to stress that it's still not the same thing, even though they are comparatively close.

The only thing proven, by the experiment, is that the neutrinos travels faster than some forms of light.

> It was big news one day but I haven't heard about it since.
It's going to take months or years for other groups to replicate the experiment. Until that happens, it's just one data point. "We did X and got Y".

>>3872829
Because the speed of light doesn't always equal c, right?

one of the big things that COULD have gone wrong has to do with general relativity. Thing is, it's not as simple as just calculating "distance divided by time", because both time and distance are relative. In particular, time flows different depending on gravital force, and since gravity is stronger in places closer to the equator, that might be what caused the error.

Not saying that's definately it, I'm just saying that for at least a few months or even years, until these errors are figured out, this won't have a lot of impact. If it turns out there were no errors, it will be one of the biggest discoveries of the century though.

>>3873798
There are much more important things than that.

>>3872795
>16000 neutrinos
>not reading paper


There were 16000 "events".

>>3873796
That is correct.

>>3874502
>>3873796
In fact; it never equals c.
It is just assumed to travel close to c. So close the the error margin overshadows it.

But we still have the puzzle of why particles with mass appear to be able to travel faster than massless "particles", do we not?

>>3874522
Photons do have mass, if that is what you are referring to.

This is why physics in the school system is bad. Too many generalizations to make any sense.

>>3874530
>Photons do have mass, if that is what you are referring to.
Nah bro. They have energy and momentum. Ain't the same thing.
inb4 e=mc^2

>>3874530
What's the mass of a photon then

>>3874530
And they keep changing the definition of mass at each stage of education, and telling us that what we learnt at the keystage before was simplified to the point of being incorrect...

Whether photons have mass depends how we are defining mass (which tends to depend upon our generation).

In modern terms, photons are considered massless.

Let's say an object was 1 light year big and capable of self movement. If it moved, would it be traveling fast than light speed?

>>3874543
Because it was.

You're following the development of science itself, bro. Before Einstein, people thought mass was what you thought it was before you learned relativity

If I carried a stick long let's say 1ly and I started turning around, what would prevent the stick from reaching the speed of light?

>>3874566
The infinite amount of energy needed to accelerate the ends, and the infinite strength to withstand the force, and infinite stiffness required to transmit that energy to the ends effectively.

>>3874540
Wtf?

Isn't momentum just mass in motion? How can you have momentum without mass?

fuck you

>>3872829
If neutrinos do travel faster than light then doesn't that mean we can send information faster than light?

That would be a big deal, wouldn't it?

>>3874566
the energy required to move something that big.

>>3874589
nope
all that would happen is that the stick would distort since the information that the rod is moving can only travel at the speed of light so you would end up with a spiral when it's being spun and it would straighten back out some time after you stopped rotating it

>>3874583
momentum is the position derivative of the lagrangian
a field has no mass and still has position derivatives

>>3874540
>>3874542
>>3874543
>>3874547
The resting mass of a photon is x*10^-16 eV (our best experimental measurement to date).
That number is figuratively infinitely small, but still bigger than 0.
Photons are ASSUMED to be massless because the mass it has is negligible. BUT; as in cases like this, it is important to remember that it still has a resting mass, else speed of light = c (which it is not).

>>3874621
No, because the speed of light has no relevance, other than being faster than light.
The relevance would come in if it was faster than c, the causality speed limit, but that is impossible.
Neutrinos just travels a little bit faster than light, and are therefor a littler closer to c.

>>3874583

E² = m²c⁴ + p²c²
m=0
∴E² = p²c²
∴ p = <span class="math">\frac{E}{c}[/spoiler]

>>3874653
no, the mass of the photon has to be 0 exactly, being anything other than 0 destroys the theory

>>3874653
>protip; if a photon was at rest it would have 0 energy and from that 0 mass

>> 3874678
>implying mass ≠ energy

>>3874682
>implying saying E=0 implies m=0 is not implying mass = energy

>>3874662
>causality speed limit
What is this term and how does it differ from the speed of light?

>>3874694

It is c: the speed of light in a vacuum of zero energy. Light is never in a vacuum of zero energy, and so never travels at c.

The neutrinos were traveling faster than c. If they weren't, why would anyone have cared?

>>3874703
This is the question I would like answered: were they travelling faster than c or faster than the speed of light?

>>3874702
light always travels at c, when there are other particles in the way it takes a longer path making it appear to travel at a speed less than c

>>3874713
c is the speed of light

>>3874730
>>3874733

And, due to quantum fluctuations, there are always virtual particles in the way in a vacuum that isn't at zero energy. Therefore light never quite reaches c.

Mass of Photon should always be
7.37249493 × 10-51 kilograms

>>3874743
>implying virtual particles can change the velocity of light
>implying virtual particles can take energy out of the universe
>implying the taking a longer paths changes the velocity of light
>implying vacuum energy can't defined as 0
>implying you know QFT

I hope many of you are trolling, because you can't be that stupid to believe that c = speed of light, when it has been explained many times in this thread that it isn't and why it isn't.

>>3874791
c is defined as the speed of light, that is it's definition
http://en.wikipedia.org/wiki/Speed_of_light
>The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics.

>>3874804
>wikipedia
fyi speed of light is ASSUMED to be c.

the speed of light is assumed to be c, where c is defined as the speed of light
so you are saying the speed of light is assumed to be the speed of light, well done, I generally assume 1 = 1 and 2 = 2 aswell

>>3874815
Nope. c is immutable. Meters are defined in units of c.

Probably a systematic error that wasn't noticed or was miscalculated.

In during retardation.

Neutrinos aren't real physical particles.
They are a model to balance equations
If you treat them as one you came to wrong conclusions like in this case.

Repeat after me:
Neutrinos aren't real physical particles.

Thank you for you attention.

>>3874848
>[citation needed]

>>3874823
1. I never said you could change the speed of light, the speed of light, c, is a fixed constant
2. the metre can be defined as the distance traveled by light in some t seconds so m=t c
2i). the units of c are m/s where as the units of m are m, so metres cannot be defined in units of c

I repeat again, the definition of c is the speed of light which is a physical constant with units of m/s

>>3874848
that explains why they've been detected irl

>>3874848
Nice assertion, now where is the data to back that ?

>>3874863
they haven't been detected directly
What they detected is the remains of some reaction