CERN breaks light speed barrier?

[JLawrence]

I am curious, how exactly do they measure the speed of these particles?
I have only an elementary understanding of physics, so this is all slightly mind boggling to me.

 

[Famine]

Then nevermind, its confirmed in my book.

The results are confirmed, but the media conclusion of "Neutrinos go faster than light!" is not. All it means is that, in that particular experiment, that result is inevitable.

As has been pointed out, we know neutrinos go at the speed of light from supernova observations - because they don't get held up by matter and move at the speed of light, massive neutrino bursts arrive at Earth before the photons from the explosion, which also move at the speed of light but get held up by matter. Photons take time to escape exploding stars, neutrinos don't. For a supernova like SN1987, that'd mean neutrinos arrive 3 hours earlier than the light and, in 1987, the neutrinos arrived 3 hours earlier than the light. If the neutrinos are faster than light - and by the magnitude OPERA's results suggest - the neutrinos would have arrived in 1982...

So at the moment, the suspects appear to be "error" or a peculiar behaviour of neutrinos not yet observed or applied to this experiment - like oscillation or dimensional tunnelling.

I am curious, how exactly do they measure the speed of these particles?
I have only an elementary understanding of physics, so this is all slightly mind boggling to me.

In this case the neutrinos are measured and enumerated as they leave CERN alone and then measured and enumerated as they arrive at Gran Sasso. The time taken is logged and distance divided by time is speed.

 

[Touring Mars]

I am curious, how exactly do they measure the speed of these particles?

From my basic understanding, it's pretty simple. They fire them from one (precisely known) location and detect them at another (precisely known) location. By using synchronised, extremely accurate atomic clocks, they can measure the length of time between the pulse and the detection. Knowing the time of flight precisely and the distance precisely, they can figure out the speed. The locations in this instance are accurate to something like 0.2 cm (by GPS), and the systematic errors associated with a range of factors add up to less than 10 nanoseconds.

In this case, they've measured the neutrinos as arriving at the detectors at 60 nanoseconds earlier than photons would to do the same distance.

 

[mattythedog]

How do they fire particles?

 

[Famine]

How do they fire particles?

Instead neutrinos are made by proton-proton beam collisions in a particle accelerator, with the collision products magnetically channelled into long, straight tunnels where they decay into neutrinos - in this case muon neutrinos. The proton-proton collision would have been generated at SPS at CERN (not the LHC - which runs at half energy right now of 7TeV, 3.5TeV per beam) and the products aimed down a 1km tunnel - in which they decay to other things - at a graphite target which absorbs everything apart from the neutrinos. They then footle along 732km to Gran Sasso.

It's worth noting that the collision products trundle down a 1km tunnel, decay into neutrinos and other things, the other things are stopped by an iron-graphite block (neutrinos don't normally interact with matter) and then the neutrinos just head through the planet to Italy. There's no special tunnel or conduit 732km long. They just pass clean through the Earth - which means the Gran Sasso collector has to be aimed at a tiny patch of nothingness they can't see through the planet despite the curvature of the Earth...

 

[JLawrence]

D=RT, basic algebra there
I suppose I was thinking it would be some ridiculous quantum shenanigans.

 

[Danoff]

 

[AOS-]

I should do that too.... Bring on your ridiculous claims!

 

[W3H5]

If one were able to move information or matter from one point to another faster than light, then according to special relativity, there would be some inertial frame of reference in which the signal or object was moving backward in time. This is a consequence of the relativity of simultaneity in special relativity, which says that in some cases different reference frames will disagree on whether two events at different locations happened "at the same time" or not, and they can also disagree on the order of the two events (technically, these disagreements occur when the spacetime interval between the events is 'space-like', meaning that neither event lies in the future light cone of the other).[23] If one of the two events represents the sending of a signal from one location and the second event represents the reception of the same signal at another location, then as long as the signal is moving at the speed of light or slower, the mathematics of simultaneity ensures that all reference frames agree that the transmission-event happened before the reception-event.[23]

However, in the case of a hypothetical signal moving faster than light, there would always be some frames in which the signal was received before it was sent, so that the signal could be said to have moved backwards in time. And since one of the two fundamental postulates of special relativity says that the laws of physics should work the same way in every inertial frame, then if it is possible for signals to move backwards in time in any one frame, it must be possible in all frames. This means that if observer A sends a signal to observer B which moves FTL (faster than light) in A's frame but backwards in time in B's frame, and then B sends a reply which moves FTL in B's frame but backwards in time in A's frame, it could work out that A receives the reply before sending the original signal, a clear violation of causality in every frame

According to this the discovery of this particle happened a while ago, or hasn't happen at all.

 

[lbsf1]

I really hope this is true because it would open up a whole new world of physics possiblities.

It is strange though that something that has been taught as such a definate up untill now is in doubt. This just shows to those who think that we are the pinacle of scientific development, that we are actually far from it.

 

[mattythedog]

It's worth noting that the collision products trundle down a 1km tunnel, decay into neutrinos and other things, the other things are stopped by an iron-graphite block (neutrinos don't normally interact with matter) and then the neutrinos just head through the planet to Italy. There's no special tunnel or conduit 732km long. They just pass clean through the Earth - which means the Gran Sasso collector has to be aimed at a tiny patch of nothingness they can't see through the planet despite the curvature of the Earth...

Again in english......

 

[Famine]

Der shiny-shiny hit each other. Der tiny whizzy whizzies get pointed by magnits.

 

[mattythedog]

Der shiny-shiny hit each other. Der tiny whizzy whizzies get pointed by magnits.

Thanks thats much clearer.

 

[Famine]

Right.

There's a big, circular tube under the ground in Switzerland. Within that tube, protons are thrown around until they're going really fast (electricity makes them go faster, magnets guide them) and then smashed into a block of graphite. When they smash into a block of graphite, they break up into smaller bits because, odd though it may seem, protons are huge.

The smaller bits are then guided down a straight tube with more magnets - electricity cannot make them go faster as they have no electrical charge. The smaller bits aren't very stable, they decay into smaller and smaller bits, some of which are called "neutrinos". Neutrinos are weird - they go the speed of light but have mass and they don't interact with normal matter (usually). In the time it takes you to think "Huh?", four billion neutrinos will have passed straight through your body and you won't have noticed a thing. So at the end of this straight tube is another block of graphite which stops everything but the neutrinos. A neutrino detector (please don't ask) detects the neutrinos, and counts them but, because they cannot be stopped, they keep going in the same direction they were sent. Forever.

Meanwhile, 732km away in Italy, there's a box underground pointed at where the neutrinos are coming from in Switzerland. The neutrinos pass straight through the Earth, because they don't interact with matter in any way (usually) so there is no need for a special, 732km long underground tube. The neutrinos enter the box in Italy - which means they have to point this box directly at the extremely small point they're coming from in Switzerland - and a neutrino detector (please don't ask) detects and counts them. Again, they cannot be stopped, so they carry on in a straight line, exiting the Earth's crust somewhere around Romania and sodding off into space.

The results of the experiment suggest that the neutrinos left Switzerland's detector and arrived at Italy's detector in less time than light would take to travel the same distance in a vacuum.

 

[mattythedog]

Right.

There's a big, circular tube under the ground in Switzerland. Within that tube, protons are thrown around until they're going really fast (electricity makes them go faster, magnets guide them) and then smashed into a block of graphite. When they smash into a block of graphite, they break up into smaller bits because, odd though it may seem, protons are huge.

The smaller bits are then guided down a straight tube with more magnets - electricity cannot make them go faster as they have no electrical charge. The smaller bits aren't very stable, they decay into smaller and smaller bits, some of which are called "neutrinos". Neutrinos are weird - they go the speed of light but have mass and they don't interact with normal matter (usually). In the time it takes you to think "Huh?", four billion neutrinos will have passed straight through your body and you won't have noticed a thing. So at the end of this straight tube is another block of graphite which stops everything but the neutrinos. A neutrino detector (please don't ask) detects the neutrinos, and counts them but, because they cannot be stopped, they keep going in the same direction they were sent. Forever.

Meanwhile, 732km away in Italy, there's a box underground pointed at where the neutrinos are coming from in Switzerland. The neutrinos pass straight through the Earth, because they don't interact with matter in any way (usually) so there is no need for a special, 732km long underground tube. The neutrinos enter the box in Italy - which means they have to point this box directly at the extremely small point they're coming from in Switzerland - and a neutrino detector (please don't ask) detects and counts them. Again, they cannot be stopped, so they carry on in a straight line, exiting the Earth's crust somewhere around Romania and sodding off into space.

The results of the experiment suggest that the neutrinos left Switzerland's detector and arrived at Italy's detector in less time than light would take to travel the same distance in a vacuum.

Thanks. I'll surprise my physics teacher with that one. And he thought I was 🤬 at it.

 

[AOS-]

Famine, you just blew my mind...

 

[homeforsummer]

Meanwhile, 732km away in Italy, there's a box underground pointed at where the neutrinos are coming from in Switzerland. The neutrinos pass straight through the Earth, because they don't interact with matter in any way (usually) so there is no need for a special, 732km long underground tube. The neutrinos enter the box in Italy - which means they have to point this box directly at the extremely small point they're coming from in Switzerland - and a neutrino detector (please don't ask) detects and counts them. Again, they cannot be stopped, so they carry on in a straight line, exiting the Earth's crust somewhere around Romania and sodding off into space.

Whilst I understand this, I do still wonder if they can be sure that the neutrinos hitting the Italian detector were the ones fired at CERN. Not that I don't think it's possible, but presuming neutrinos can emerge from any energy source in the cosmos (say, a star) and pass through essentially everything, what's to say that some neutrinos hadn't already been passing through the Earth/CERN ahead of those "fired" at Italy, and those were the ones detected a few billionths of a second early?

It's a bit like dropping water from a pipette into the Pacific Ocean and then scooping up some water a few kilometres straight down claiming it's the same molecules of hydrogen and oxygen as those from the pipette.

 

[Exorcet]

Whilst I understand this, I do still wonder if they can be sure that the neutrinos hitting the Italian detector were the ones fired at CERN.

Interference is everywhere. I don't know how they determined where the neutrinos came from, but everything that processes a signal must do the same thing.

Radar, cell phones, antennae, etc all must pick out the signal that they are looking for from random, or sometimes purposely made (radar jamming) noise.

A simple guess would be that background neutrino emissions are fairly constant, and that the magnitude of the CERN emission was measured at CERN, allowing it to be compared to the emission detected elsewhere, which would appear as a spike.

 

[Famine]

Whilst I understand this, I do still wonder if they can be sure that the neutrinos hitting the Italian detector were the ones fired at CERN. Not that I don't think it's possible, but presuming neutrinos can emerge from any energy source in the cosmos (say, a star) and pass through essentially everything, what's to say that some neutrinos hadn't already been passing through the Earth/CERN ahead of those "fired" at Italy, and those were the ones detected a few billionths of a second early?

Naturally occurring neutrinos come in three flavours - tau neutrinos, muon neutrinos and electron neutrinos. Typically background neutrino counts would be a nearly equal ratio of all three (just to screw with you, they also have antiparticles - tau antineutrinos, muon antineutrinos and electron antineutrinos) and, importantly, they're going in random directions - typical neutrino sources are stars and we're surrounded by them!

The ones used in the neutrino oscillation experiment were all muon neutrinos and all going in the same direction - a direct line from CERN to Gran Sasso - and they were counted out and back in again. The chances of a 100% batch of muon neutrinos in the same number heading the same direction at once being due to background are about the same as my house being hit by a satel

 

[homeforsummer]

The chances of a 100% batch of muon neutrinos in the same number heading the same direction at once being due to background are about the same as my house being hit by a satel

Gotcha. I knew there'd be a logical explanation, but thought I'd put the theory out there.

And antineutrinos? Antimatter is hard enough to store and measure without antineutrinos being around passing through matter and antimatter like they own the place...

 

[Hun200kmh]

Right.

.... A neutrino detector (please don't ask) ....

I didn't dare, but I looked them up. And suddenly I thought I was seeing a picture from the Movie "Eagle Eye". I like these things

 

[CodeRedR51]

Right.

There's a big, circular tube under the ground in Switzerland....

Thanks, perfectly clear for my small brain. :tup:

 

[Dennisch]

See, it was a good idea to bring Famine into this thread, now even more people understand this heavy stuff.

But, as you brought them up already, the neutrino detector and how it works, pretty easy to read and understand at Wiki. Clickie

 

[wfooshee]

Whilst I understand this, I do still wonder if they can be sure that the neutrinos hitting the Italian detector were the ones fired at CERN. Not that I don't think it's possible, but presuming neutrinos can emerge from any energy source in the cosmos (say, a star) and pass through essentially everything, what's to say that some neutrinos hadn't already been passing through the Earth/CERN ahead of those "fired" at Italy, and those were the ones detected a few billionths of a second early?

It's a bit like dropping water from a pipette into the Pacific Ocean and then scooping up some water a few kilometres straight down claiming it's the same molecules of hydrogen and oxygen as those from the pipette.

I already did this, in post #48. But Famine's point that they are all one kind of neutrino (result of the particle decay at CERN) rather than a mix of the natural three types kinda puts that one to bed.

 

[VEXD]

It's easy really, they all pass through the Purpl painter as they head off to Gran tur sasso.

When they get there, if they're Purpl, then they are the ones the swiss painted, and have taken not very long to do 700 odd Kilometres.....

Or they are the ones flying straight.

Or something.

I like Brian Cox.

👍

 

[Dan_]

Wow, I was quite disappointed with the fact that nothing could actually exceed the speed of light, it was like an unbeatable limitation that you just had to accept. Interesting findings.

Thanks to Mr. Fa for clearing the terms and acronyms into a noob-friendly post. 👍

 

[W3H5]

It is strange though that something that has been taught as such a definate up untill now is in doubt.

Many would constitute disproving things as being science. The world was once flat, remember? It was a theory, a theory can never be a definite because then it would be fact.

How do they fire particles?

In a particle furnace.

I'll get my coat.

 

[terminator363]

So, Famine are you saying these "Neutrinos" can pass through anything cleanly? So for example if I were to walk into a blast of Neutrinos I would be find and they would have dodged or missed all my cells? On the other hand could I get cut into little bits and pieces? I'm a bit confused as to how they can just go through anything without any interference.

 

[W3H5]

They would pass through you the same way gamma radiation would I'm guessing. The have no mass like photons, you don't see photons shredding windows do you?

 

[burgermaster]

Right.

There's a big, circular tube under the ground in Switzerland. Within that tube, protons are thrown around until they're going really fast (electricity makes them go faster, magnets guide them) and then smashed into a block of graphite. When they smash into a block of graphite, they break up into smaller bits because, odd though it may seem, protons are huge.

The smaller bits are then guided down a straight tube with more magnets - electricity cannot make them go faster as they have no electrical charge. The smaller bits aren't very stable, they decay into smaller and smaller bits, some of which are called "neutrinos". Neutrinos are weird - they go the speed of light but have mass and they don't interact with normal matter (usually). In the time it takes you to think "Huh?", four billion neutrinos will have passed straight through your body and you won't have noticed a thing. So at the end of this straight tube is another block of graphite which stops everything but the neutrinos. A neutrino detector (please don't ask) detects the neutrinos, and counts them but, because they cannot be stopped, they keep going in the same direction they were sent. Forever.

Meanwhile, 732km away in Italy, there's a box underground pointed at where the neutrinos are coming from in Switzerland. The neutrinos pass straight through the Earth, because they don't interact with matter in any way (usually) so there is no need for a special, 732km long underground tube. The neutrinos enter the box in Italy - which means they have to point this box directly at the extremely small point they're coming from in Switzerland - and a neutrino detector (please don't ask) detects and counts them. Again, they cannot be stopped, so they carry on in a straight line, exiting the Earth's crust somewhere around Romania and sodding off into space.

The results of the experiment suggest that the neutrinos left Switzerland's detector and arrived at Italy's detector in less time than light would take to travel the same distance in a vacuum.

Dear santa. I know what i want for chrismas. Famine as my physics teacher.