Speed!

Hi everybody. When I took astronomy in college my professor (or maybe he was a doctor) said that the fastest thing known in the universe is the speed that a red giant shrinks when it implodes. He said that the the red giant our sun will become will go from touching Mars all the way down to something the size of say something like Jupiter in a matter of seconds (3 or 4 seconds.) Does anyone know what the acutally speed is? Tried googling it and tried googling fastest thing known to man. Most websites still say light but then, isn't gravity proven now to have a speed and that speed is faster than light too?

- Thanks, David/Wildcard

Firstly, thanks for joining David!!!

I'm not too sure what the fastest thing in the universe is, when I googled it I got exacty the same!

Gravity travels at c, the speed of electromagnetic radiation in a vacuum if general relativity is to be believed. The sun will certainly not be doing any rapid shrinking once it becomes a red giant, it is too small for that sort of nonsense. Your professor (who was probably a doctor as well) was likely thinking about stars that are massive enough for core fusion to procede all the way to iron. Stars with iron in their core can no longer carry out fusion reactions to supply the energy needed to generate the temperature necessary to prevent gravitational collapse. It is the core of such stars that undergoes rapid collapse, the outer layers follow more slowly but accelerate. Once the core has become dense enough it stops collapsing suddenly and rebounds sending a shock wave out through the star. The shockwave meets outer layers falling in and a supernova results. The sun will likely not get much further than carbon in its core so will just eject its outer layers as a planetary nebula allowing the core to cool slowly as a white dwarf.

Fastest thing known to man apart from light? I am guessing that particles accelerated in large magnetic fields would be likely candidates. Either the stuff they play with at CERN or particles ejected from active galactic nuclei would be my guess.

Wow, thanks Sharukin! I love reading information like that. But now I pose to you the question, how fast does the core of one of these suns collapse?

I have been following the CERN project. I cant wait to see what they find in a year when they fire it all the way up.

The really interesting question is the fastest object with mass.

I had to do many equations on this subject and it becomes complex because the observed speed from distance is much different to the perceived speed as the object. Due to the changing of time no object (will perceive as the object) to travel faster than the speed of light. However from distance it may occur that speeds greater than light may be observed. 

chess4david wrote:

The really interesting question is the fastest object with mass.

I had to do many equations on this subject and it becomes complex because the observed speed from distance is much different to the perceived speed as the object. Due to the changing of time no object (will perceive as the object) to travel faster than the speed of light. However from distance it may occur that speeds greater than light may be observed. 

The fastest object with mass is likely one of those particles accelerated by a big magnetic field. Even an electron has mass!

wildcard wrote:

Wow, thanks Sharukin! I love reading information like that. But now I pose to you the question, how fast does the core of one of these suns collapse?

I have been following the CERN project. I cant wait to see what they find in a year when they fire it all the way up.

It takes less than a second for the core to collapse. How fast is the actual stuff going? Well, that will depend on when and where you measure it. At the start of the collapse the speed is tiny. The core is a very massive object (several suns packed into a small space) so the gravitational acceleration is large. Just before the core stops collapsing and rebounds the matter is travelling at substantial fraction of the speed of light.

Wow thanks for the information

True. There are mathematical models of core collapse but none actually predict what is observed. The best match for observations of Type II supernovae come from numerical simulations of core collapse using fluid dynamics codes.

I am really enjoying reading and learning from these comments. Keep it up.

The computational dynamics still doesn't match the observations, but it's far better than it used to be. We calculated how fast a supernova shock front should travel but I can't find the work so I'll have to have a look when I get back to uni, but it was pretty fast!

The particles at CERN will be travelling at a speed of >0.99999c or something along those lines, which is severely relativistic, some interesting things should drop out of it I can't wait. :)

Chess4David: The fastest speed at which you can transmit information of any form is the speed of light.

I don’t think I explained things last time so I will try again. This metaphor is used a lot so I apologise for all those who have heard it before. If you imagine a train travelling at 30 ms^-1 and you turn on its front light you expect the speed to be 30ms^-1 + c. In reality as you look at the train, time is slower so that the light is travelling still at perceived c. The light never travels faster than c. Hence even if you expect a situation to have a speed faster than c it is probable that an alteration to the continuum of time will still give the observation of c. Einstein did a lot of work on this proving Newton wrong.

The faster an object travels the greater the mass. Thus an object with mass can never travel faster than the speed of light due to the fact that the energy required can never be generated as it is infinite. Thus it may be thought that an object without mass may travel faster than light but not one with mass.

I was at CERN last summer while it was being put together. It is very impressive. Higgs boson and Muon detection was the focus of why I went. There are other experiments occurring at the LHC but they are not looking for partials faster than the speed of light! The experiments at LHC could take years for their data to be analysed so don’t expect major results soon!

I can see people coming out with some ideas to this so I shall try to stunt them first- A neutrino though thought of as mass-less, is only so when stationary. It is thought that is has some mass when it has velocity.

An electron will never travel faster than the speed of light! – Just trust me on this one! The mass of an electron is massive in comparison to some subatomic particles.

Magnetic field particle accelerators have never claimed or expected to generate speeds of partials faster than light. Then don’t have infinite power so they know they can’t.

Active Galactic Nuclei have never been theorised to generate particles faster than the speed of light in their ‘jets’

I have no idea why ck516 addresses me with: Chess4David: The fastest speed at which you can transmit information of any form is the speed of light. I never mentioned information in my first comment. I am perfectly aware that fiber-optics can transfer information at the speed of light (rather obvious why) but the transfer of this to memory or the processing of data from this is colossally slower than the speed of light. Radio and TV etc are other examples. All electromagnetic waves travel at the speed of light (again for obvious reasons)

There are arguments that some waves may travel faster than the speed of light but this again is more optimistic guessing than reality.  

I hope this some what fragmented ramble sorts out the lose ends arising from the perception of my first comment and resolves some of the issues here!  

No one said anything about anything travelling faster than c as far as I can see. I certainly did not say anything about particles in LHC or from AGN travelling faster than c. All I said was that those would be likely candidates for the fastest massive objects known.

Einstein did not prove Newton wrong for two reasons:

1. Proof is a mathematical concept that does not work in science. A scientist gathers evidence from experiment and/or observation, creates a theory to explain that evidence and then looks for more experimental and/or observational evidence to back up the theory. Scientific theories are never proved.

2. Newton was not wrong. General relativity reduces to Newtonian gravitation when gravitational fields are not large and speeds are small.

If you want to believe that light suddenly travels faster because it is emitted from a moving object then go ahead! 

Newton was wrong! Even at small speeds objects increase fractionally in mass! Thus direct addition of velocities NEVER WORKS because there is always a fractional deficit! Newton never expected this! Ok maybe it takes 20 decimal places to find the difference but at the end of the day Newton was wrong! If you do the mathematics to place a satellite in orbit and you want to calculate its location if you use newton then you will be over 25m out! Those are not particularly fast speeds to be dealing with.

You can prove a theory wrong! You just cant prove it right! Einstein showed newton was wrong! There is evidence that newton is wrong! 

If Newton was alive today he would say he was wrong!

Keeping with wave/particle duality then a photon would be the fastest particle known to man! 

chess4david wrote:

 It was this bit that threw me, I wasn't sure what you were trying to say here.

I wasn't talking about fibre-optics or anything complex, just that the fastest speed any information can be transferred is c.

The photon is a strange one!

Isn't saying Newtonian Gravitation is wrong a bit like saying Maxwell's equations are wrong? Maxwell's equations had to me modified to allow for relativity and various other things, but they still hold in free space and at classical speed.

We know GR is flawed as well...we still havn't reached the bottom of this, and we probably never will.

However from distance it may occur that speeds greater than light may be observed. 

Again does time exist? If it does not then neither does speed :P 

Wow I love reading these comments, keep them flowing in.

chess4david wrote:

If you want to believe that light suddenly travels faster because it is emitted from a moving object then go ahead!

Newton was wrong! Even at small speeds objects increase fractionally in mass! Thus direct addition of velocities NEVER WORKS because there is always a fractional deficit! Newton never expected this! Ok maybe it takes 20 decimal places to find the difference but at the end of the day Newton was wrong! If you do the mathematics to place a satellite in orbit and you want to calculate its location if you use newton then you will be over 25m out! Those are not particularly fast speeds to be dealing with.

You can prove a theory wrong! You just cant prove it right! Einstein showed newton was wrong! There is evidence that newton is wrong!

If Newton was alive today he would say he was wrong!

Keeping with wave/particle duality then a photon would be the fastest particle known to man!

Never said anything about light travelling faster if it is emitted from a moving object either. I think you need to read what people write instead of just assuming you know by a quick scan.

If Newtonian dynamics is so wrong why do NASA and co still use it to place probes in orbit around Saturn and other planets? Why are researchers still using it to work out how globular clusters work? There is evidence that general relativity is a more accurate description of the universe than Newton's description but there is a trade off between accuracy (do I really need more decimal places?) and how feasible the calculations are. If I am mucking about with GPS then I need to take account of relativity. Incidentally, the correction is not due to the speed of the satellite but due to the difference in gravitational field between the surface of the Earth and the satellite's altitude. For models of galaxies good old Newtonian dynamics and Newtonian gravity will do nicely. I may have to apply a correction for the difference between Newtonian orbital speeds and the observed orbital speeds of stars in galaxies but the Newton's description is accurate enough for my purposes. Interestingly, even relativity will not give me a perfect match for galactic rotation curves so Einstein was wrong as well and we have evidence (you can say proof if you like).

If Newton were alive today it is highly unlikely he would admit to being wrong, he was not inclined to admit error publicly even when he was clearly in the wrong.

The photon may be the fastest particle known to man which is essentially what I said - nothing moves faster than electromagnetic radiation i.e. photons or waves according to choice. However, the fastest massive particle (that's what I said, go back and read it if you have any doubts) is not a photon since photons have no mass. I suppose the fastest massive particles are potentially neutrinos but the difficulty in detecting them would make measuring their speed impossible with current technology.

For a start Newton stole most of his work from other members of the royal society. What work can be attributed to him is tricky to say the least. Case example: a member starts work of gravity, Newton all of a sudden claims to have been hit by an apple many years ago and hence thought of it first! 

Secondly Nasa don't just use Newton. They have to calculate using Einstein's equations the relative time difference that occurs due to perception and real object speeds having a deficit. I know this as a fact having spoken to NASA and CASC scientists myself about issues of time perception but what the hey! You know best. 

I know even Einstein was wrong but the fact remains he was closer to the real truth than Newton. 

Interestingly if you actually read up on Newtons corpuscular theory of light then you will see newton had no idea what happens at high speed. His work on gravity has been massively polished up to be served as it is now. 

' Never said anything about light traveling faster if it is emitted from a moving object either. I think you need to read what people write instead of just assuming you know by a quick scan.' I was being ironic to show my point. That is a conclusion Newton would have come to.

Neutrinos are tricky as they are meant to have momentum but no one knows their mass. A lot of what we know about them comes from energy conservation laws and deductions rather than observations. A lot of the best science in this area is done in Japan. 

Please try not to take any hyperbole too heart this time.

    wildcard, let's say you have a straight line of christmas lights 600,000 kilometers long and you time them to go out in succession (one after the other before it) so that it takes one second. Now it appears the light going out is traveling twice as fast as C but actually nothing in the experiment is "traveling" faster than C, it's just our perception. Likewise no particles or waves are going faster than light in the collapse, it just appears that way. Remember, the star is just a big ball of gas (an astronomical amount of particles) held together by gravity and internal pressures, it's not one individual thing, so the act of collapsing may be faster than light but no einsteinion rules are being broken. I'm sure the science guys in our group can explain it better