Post by: pensador on 06/05/2019 16:53:38
https://futurism.com/newtonian-physics-vs-special-realtivity
Post by: Bored chemist on 06/05/2019 17:03:03
because they contradict eachother
Post by: Colin2B on 06/05/2019 17:20:59
Can Special Relativity be derived from Newtonian mechanics? :-\To add to what @Bored chemist said, Newtonian mechanics does not contain any theory of electromagnetism which is key to special relativity.
Post by: yor_on on 06/05/2019 19:48:56
Hup does not give you that
It might give you 'statistics'
But that's the long run
It does not include yourself.
Post by: pensador on 06/05/2019 20:15:54
How would special relativity give a different answer in this case to a Newtonian explanation of the same thing. Both are modelling the exact same light clock. Both are limited by the speed of light, are they not?
Post by: pensador on 06/05/2019 20:18:05
No Newtonian mechanics came from a belief, that the world could be counted at.
Hup does not give you that
It might give you 'statistics'
But that's the long run
It does not include yourself.
Does the HUP limit the speed of light to c via quantum foam. ?
How is the HUP related to special relativity or Newton mechanics ?
Post by: Bored chemist on 06/05/2019 20:47:42
Per Newton it will accelerate forever.
Per Einstein it will accelerate less as time goes on, because there's a limit at C.
Post by: yor_on on 06/05/2019 21:18:10
As for a quantum foam? Under Planck scale?
Your guess is as good as mine.
Scaling it up 'c' will be a limit though.
Post by: yor_on on 06/05/2019 21:24:23
Post by: evan_au on 06/05/2019 23:04:16
Quote from: flummoxed
The photon moves further and so ticks slower for a stationary observer.Perhaps you are thinking that Newton could have discovered the Doppler effect long before Doppler: the frequency of light shifts towards the red when you are moving away from an object.
But this depends on understanding light as a wave - and Newton came down on the side of the debate that said "light is a particle".
See: https://en.wikipedia.org/wiki/Corpuscular_theory_of_light#Isaac_Newton
Now we understand that light has characteristics of both a wave and a particle, so we can apply Doppler shift to light (such as in Police radar).
But this is a long way from understanding that:
- Light has a specific speed (in a vacuum): would not have been known until Maxwell's equations of electromagnetism
- Every observer sees light with this speed (in their own lab)
- This paradox is related to time dilation of observers moving relative to each other
- The existence of this paradox would not have been understood before the Michelson-Morley experiment
See: https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment#Most_famous_%22failed%22_experiment
Post by: pensador on 07/05/2019 00:00:11
If I start with a 1 Kg rock and apply 1 newton to it then it will accelerate at 1m/s/s.
Per Newton it will accelerate forever.
Per Einstein it will accelerate less as time goes on, because there's a limit at C.
Am I correct in thinking acceleration is to do with general relativity and not special relativity? Special relativity deals with none accelerating objects does it not.
Using simple algebra and tracing the path of a photon between two moving mirrors, will result in time dilation for an observer in a stationary reference frame. Assuming of course that light is fixed at c for the observer and someone moving with the mirrors.
Would Newton have assumed that light speeded up for the observer, so that the clocks would still tick at the same rate, for the observer and for someone moving with the mirrors?
Post by: pensador on 07/05/2019 00:21:13
Perhaps you are thinking that Newton could have discovered the Doppler effect long before Doppler: the frequency of light shifts towards the red when you are moving away from an object.But this depends on understanding light as a wave - and Newton came down on the side of the debate that said "light is a particle".
Both Newton and Einstein viewed photons as particles.
How does viewing light as a wave affect a photons movement between two moving none accelerated mirrors?
I understand special relativity has been inccorporated into quantum field theory and QED. But Special relativity does not need Quantum field theory. What am I missing in what way does special relativity include waves and quantum theory?
Post by: Halc on 07/05/2019 02:53:02
Am I correct in thinking acceleration is to do with general relativity and not special relativity? Special relativity deals with none accelerating objects does it not.Special relativity deals with acceleration just fine. General relativity introduce the equivalence principle with allowed the properties of gravitational fields to be (locally) described in terms of accelerating reference frames.
Newton's equations did not cap speed of mass at c. F=ma. If you continue to apply force to an object, the acceleration will continue up to any beyond c. With SR, acceleration (not proper acceleration) drops off and that same force just drives up m after a while. They do this in particle accelerators where getting a particle to near light speed is easy, but then they just add mass to the thing until up to the limits of the magnetic field to hold it in its path.
Quote
Using simple algebra and tracing the path of a photon between two moving mirrors, will result in time dilation for an observer in a stationary reference frame.Reference frames are not stationary. Things are stationary relative to them.
That said, I see what you are getting at. Newton probably wouldn't consider the light device to be a clock since without knowing its speed, there is no way to tell how far the light needs to travel. Not like there is any real light clock anyway. How would you get it to work? You can't measure a photon going between mirrors, counting cycles. A photon can be measured but once.
Post by: pensador on 07/05/2019 10:36:47
They do this in particle accelerators where getting a particle to near light speed is easy, but then they just add mass to the thing until up to the limits of the magnetic field to hold it in its path.
How is this explained, is it that does the particle shrinks to the observers, and Its inertia and or wavefunction frequency, increases.
Post by: geordief on 07/05/2019 11:51:48
They do this in particle accelerators where getting a particle to near light speed is easy, but then they just add mass to the thing until up to the limits of the magnetic field to hold it in its path.Can it be argued that the force applied in a particle accelerator has its own speed of propagation and that it would for this reason be unreasonable for the particle to be accelerated to a speed higher than that of the speed of the force itself?
If true ,would that observation have any theoretical consequences?
Post by: Halc on 07/05/2019 12:33:36
How is this explained, is it that does the particle shrinks to the observers, and Its inertia and or wavefunction frequency, increases.Newton has no explanaion. He'd say that a continued force would give it more kinetic energy (correct) and so the v must be going up (it is accelerating indefinitely, wrong). E = ½MV², so V can get highter than c. You could outrun light just like you could theoretically accelerate past sound. Neither had been demonstrated in Newton's time.
Anyway, SR says a (acceleration in F=ma) approaches zero as v approaches c, so kinetic energy must be gained by an increase of mass. You called it inertia. Same thing.
Can it be argued that the force applied in a particle accelerator has its own speed of propagation and that it would for this reason be unreasonable for the particle to be accelerated to a speed higher than that of the speed of the force itself?That would imply that as a particle approached c, the force on it would decrease, which would be measurable in the drop in reaction magnitude. The recoil of a railgun would approach zero if the projectile is already going fast.
If true ,would that observation have any theoretical consequences?
The force is applied via a field set up along the entire length of the accelerator, so is is not an issue of trying to keep up. The particle isn't pushed from some endpoint like it is in a chemical gun or a light sail, both of which would nevertheless have recoil even without a projectile since it uses mass to convey force to the projectile whether it is there or not. Fire a cannon without a ball and it still has some recoil due to the accelerating powder, but not nearly as much as with the ball.
Post by: geordief on 07/05/2019 13:48:28
which would be measurable in the drop in reaction magnitude.How would that be measurable. Isn't the acceleration (change in speed) the only measurable effect?
The force is applied via a field set up along the entire length of the accelerator, so is is not an issue of trying to keep up. The particle isn't pushed from some endpoint like it is in a chemical gun or a light sail, both of which would nevertheless have recoil even without a projectile since it uses mass to convey force to the projectile whether it is there or not. Fire a cannon without a ball and it still has some recoil due to the accelerating powder, but not nearly as much as with the ball.
Yes ,I appreciate that the force is applied equally at every point along the trajectory (no one point of emanation) ,but does this force still always have a (same) speed of propagation at every point regardless?
If this force propagates at c how could it propel any object to a faster speed?
Am I right to imagine that the speed of propagation of force is actually a valid concept?( ordinary physical waves in a medium do apply a force that applies an acceleration as a function of their speed of propagation;would the same hold for em waves?)
I apologize if I am showing my ignorance ;-)
Post by: geordief on 07/05/2019 18:40:46
Hope it goes well.
Post by: Colin2B on 08/05/2019 09:03:27
How is the HUP related to special relativity or Newton mechanics ?Relativity makes accurate predictions for all sizes of objects from astronomical to atomic/quantum, but HUP is only relevant to atomic/quantum.
You might better turn your question around and ask whether Newtonian mechanics can be derived from special relativity: answer, it can as it is an approximation of relativistic mechanics at low speeds.
Post by: pensador on 08/05/2019 10:09:14
How is the HUP related to special relativity or Newton mechanics ?Relativity makes accurate predictions for all sizes of objects from astronomical to atomic/quantum, but HUP is only relevant to atomic/quantum.
You might better turn your question around and ask whether Newtonian mechanics can be derived from special relativity: answer, it can as it is an approximation of relativistic mechanics at low speeds.
Yor_on raised the HUP in post 3, I guess ultimatly all field equations will be replaced, or modified to include a quantum mechanical explanation.
Ah Ah Bingo; Do you have a paper showing how the approximate derivation is done??
Post by: Colin2B on 08/05/2019 22:53:27
Ah Ah Bingo; Do you have a paper showing how the approximate derivation is done??No one would write a paper on something that is so obvious, just follow the Lorentz transforms at low speeds.
Note that Newtonian mechanics vs relativistic mecanics is not the end of the story, Einstein’s paper which introduced special relativity was on a problem in electrodynamics which he solved.
I guess ultimatly all field equations will be replaced, or modified to include a quantum mechanical explanation.You guess wrong, qft is a development of qm to explain particle creation/destruction. In qft the photon description is based on Maxwell’s equations.
Post by: pensador on 09/05/2019 09:59:41
Ah Ah Bingo; Do you have a paper showing how the approximate derivation is done??No one would write a paper on something that is so obvious, just follow the Lorentz transforms at low speeds.
Note that Newtonian mechanics vs relativistic mecanics is not the end of the story, Einstein’s paper which introduced special relativity was on a problem in electrodynamics which he solved.I guess ultimatly all field equations will be replaced, or modified to include a quantum mechanical explanation.You guess wrong, qft is a development of qm to explain particle creation/destruction. In qft the photon description is based on Maxwell’s equations.
Some one has written a pdf involving NM and SR http://www.trybasics.com/ewExternalFiles/Understanding%20SRT%202c%204-2-17.pdf
I started reading it last night, I require a print out to follow it.
I think maybe it is time to buy another book, does anyone have a good recommendation for a book on QFT including a good section on QED. ??????????????
I had viewed radio waves as being electrical polarisations of the EM field prior to this thread. Now I know a radio wave is made up of photons which are NOT influenced by electrical or magnetic fields. These photons may be due to virtual particle pairs near the transmitter recombining to produce a wave of photons.
Post by: Colin2B on 09/05/2019 16:40:23
Some one has written a pdf involving NM and SR http://www.trybasics.com/ewExternalFiles/Understanding%20SRT%202c%204-2-17.pdfI had a quick look at the paper. Quite amusing, let me know when you spot the problems.
I started reading it last night, I require a print out to follow it.
These photons may be due to virtual particle pairs near the transmitter recombining to produce a wave of photons.Or not! ;D
Post by: pensador on 10/05/2019 10:47:09
Some one has written a pdf involving NM and SR I started reading it last night, I require a print out to follow it.I had a quick look at the paper. Quite amusing, let me know when you spot the problems.These photons may be due to virtual particle pairs near the transmitter recombining to produce a wave of photons.Or not! ;D
A number of issues have already been pointed out on this thread, and yes I have spotted what I think are problems.
Or What :)
Edit I must admit I only glanced at the link before posting it, in response to your other none answer :)
Post by: Colin2B on 10/05/2019 14:42:50
I have spotted what I think are problems.To giive him his due, it is a better attempt at a new theory/relativity denyer then most, but suffers from the problem most do, a lack of understanding of special relativity and in this case also of Galilean relativity
Post by: yor_on on 10/05/2019 19:23:19
It's actually very weird.
And you have one of two simple choices.
Either you believe it to be correct, or you don't.
Post by: Colin2B on 10/05/2019 23:20:01
As far as I get it you're correct. " Am I correct in thinking acceleration is to do with general relativity and not special relativity? Special relativity deals with none accelerating objects. "No, he’s incorrect.
Although SR is most often used for contant velocity, it can handle acceleration.
Post by: jeffreyH on 11/05/2019 21:17:43
http://www.thestargarden.co.uk/Newtons-theory-of-light.html
Nothing about the speed of light though. Here is more on that journey of discovery.
http://www.thestargarden.co.uk/Speed-of-light.html
Post by: jeffreyH on 11/05/2019 21:30:48
Post by: jeffreyH on 11/05/2019 22:51:34
https://en.m.wikipedia.org/wiki/Woldemar_Voigt
Post by: jeffreyH on 11/05/2019 22:56:18
Post by: set fair on 12/05/2019 01:58:50
Post by: Colin2B on 12/05/2019 07:59:53
Special relativity was derived from Newtonian physics.Please explain how.
Post by: jeffreyH on 12/05/2019 12:13:23
https://en.m.wikiversity.org/wiki/Light_in_moving_media
This includes media in motion. All of this has a part to play in special relativity. Newtonian mechanics cannot produce the equations of special relativity. If you believe it can you are misguided. If you are saying it can just to be contrary then you are being dishonest. Which is it?
Post by: jeffreyH on 12/05/2019 14:33:53
Post by: set fair on 12/05/2019 14:53:22
Special relativity was derived from Newtonian physics.Please explain how.
Einstein took Newtonian theory and the observation that the speed of light was the same whether the observer was at rest or moving relative to the light source and that led him to the special theory of relativity.
Post by: Colin2B on 12/05/2019 15:02:37
Einstein took Newtonian theory and the observation that the speed of light was the same whether the observer was at rest or moving relative to the light source and that led him to the special theory of relativity.Wrong, that’s not what he did.
Guess again.
Post by: jeffreyH on 13/05/2019 21:16:54
Post by: jeffreyH on 13/05/2019 21:20:42
Post by: geordief on 13/05/2019 22:17:42
Here is another point to ponder. The speed of light through a medium is dependent upon the refractive index of the medium. What is the refractive index of the vacuum? The vacuum is an absence of anything. So why is the value of c the speed of light in the vacuum? Why not 10c or 1000c or 602.5c? What exactly is limiting the speed of light?Mass seems to make things move more slowly so massless objects should move fastest.
Since things must move at a finite speed (the alternative would be that everything would happen at the same time and causality would collapse),massless objects must move at this maximum but finite speed.
This speed is found experimentally to be c.
So nothing is limiting the speed of light and it just moves at the maximum speed.
That is my take.I hope it is right ;-)
Post by: Colin2B on 13/05/2019 23:15:49
Mass seems to make things move more slowly so massless objects should move fastest.That logic doesn’t work here. Mass makes things accelerate more slowly for a given force, but final speed is dependent on both force and time, both of which are variable.
Since things must move at a finite speed (the alternative would be that everything would happen at the same time and causality would collapse)Again this isn’t logical. Even if everything could move at infinite speed it doesn’t mean everything would happen at once.
This speed is found experimentally to be c.It hasn’t been found experimentally, it is a consequence of SR. No experiments to date have taken objects with mass to c, but the experiments below c show that the speed/energy relationship follows the predictions of SR and therefore c appears to be the limiting speed for objects with mass.
Post by: Bogie_smiles on 13/05/2019 23:33:43
There is no perfect vacuum, and in that context, there is never an “absence of anything”. So can we say that the refractive index is variable, relative to the medium?Here is another point to ponder. The speed of light through a medium is dependent upon the refractive index of the medium. What is the refractive index of the vacuum? The vacuum is an absence of anything. So why is the value of c the speed of light in the vacuum? Why not 10c or 1000c or 602.5c? What exactly is limiting the speed of light?Mass seems to make things move more slowly so massless objects should move fastest.
Since things must move at a finite speed (the alternative would be that everything would happen at the same time and causality would collapse), massless objects must move at this maximum but finite speed.
This speed is found experimentally to be c.
So nothing is limiting the speed of light and it just moves at the maximum speed.
That is my take. I hope it is right ;-)
Refractive index
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium. It is defined as.
From Wikipedia, the free encyclopedia
A ray of light being refracted in a plastic block
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how fast light propagates through the material. It is defined as
n=c/v
where c is the speed of light in vacuum and v is the phase velocity of light in the medium. For example, the refractive index of water is 1.333, meaning that light travels 1.333 times as fast in vacuum as in water.
Edit: See Wiki on Refractive index
Post by: Colin2B on 14/05/2019 09:14:08
There is no perfect vacuum, and in that context, there is never an “absence of anything”. So can we say that the refractive index is variable, relative to the medium?You have copied a large section of Wiki but don’t seem to have answered the question or shown it’s relevance to the topic.
Although there is rarely a perfect vacuum, space is extremely close (even the speed of light in air is not far off vacuum) and CERN is able to produce pressure of the order of 10-10 to 10-11 mbar - a vacuum almost as rarefied as that found on the surface of the Moon. At these pressures there is little practical difference between the theoretical speed of light in vacuum and that measured in the accelerator.
So, within the limits we can measure SR hangs together and tests in particle accelerators confirm this.
Post by: geordief on 14/05/2019 13:06:59
Mass seems to make things move more slowly so massless objects should move fastest.
That logic doesn’t work here. Mass makes things accelerate more slowly for a given force, but final speed is dependent on both force and time, both of which are variable.
Quote from: geordief on Yesterday at 22:17:42
Since things must move at a finite speed (the alternative would be that everything would happen at the same time and causality would collapse)
Again this isn’t logical. Even if everything could move at infinite speed it doesn’t mean everything would happen at once.
I accept that.
Is there any reason to suppose that the maximum speed limited is connected to the size of the observable plus unobservable universe?
Have I gone off topic now?
Post by: Colin2B on 14/05/2019 14:52:31
Is there any reason to suppose that the maximum speed limited is connected to the size of the observable plus unobservable universe?No, size never came into the equation.
It has to do with electrodynamics, specifically the physics of electric and magnetic fields as derived by Faraday, Amper, Coulomb and Gauss, and what happens when they move. Einstein just followed it through to its logical conclusion. I say ‘just’, but in reality it was a big leap solving problems which had been puzzling scientists for quite a while.
This is also why you can’t derive SR from Newtonian mechanics.
Post by: jeffreyH on 15/05/2019 20:44:27
When you argue against established knowledge you need to be able to support your position. You cannot simply guess that you have found a 'loophole'. That benefits no one.
Newton was around at a time when Galilean relativity was still the norm. He was a very clever man but was limited in his knowledge nonetheless.
Post by: pensador on 16/05/2019 09:49:13
Here is another point to ponder. The speed of light through a medium is dependent upon the refractive index of the medium. What is the refractive index of the vacuum? The vacuum is an absence of anything. So why is the value of c the speed of light in the vacuum? Why not 10c or 1000c or 602.5c? What exactly is limiting the speed of light?Mass seems to make things move more slowly so massless objects should move fastest.
Since things must move at a finite speed (the alternative would be that everything would happen at the same time and causality would collapse),massless objects must move at this maximum but finite speed.
This speed is found experimentally to be c.
So nothing is limiting the speed of light and it just moves at the maximum speed.
That is my take.I hope it is right ;-)
You can view c as being a fixed constant that goes in exactly straight lines.
But
It is reasonable to assume light is limited by the medium it travels through "in all cases". For space c=1/
Light speed has been measured to be c, as it travels through space which is full of virtual particles, CBR, and various other little bits of matter :) which probably dont matter too much in the scheme of things. It will be absorbed and reemitted and interact with virtual particles it passes through. Similiar to the way it moves through other materials.
Space has no refractive index and is transparent to electromagnetic waves.
Generally the speed of light is thought to be c, but these guys think they might be able to go faster :)
https://www.livescience.com/29111-speed-of-light-not-constant.html ;D
Post by: Colin2B on 17/05/2019 10:55:10
Light speed has been measured to be c, as it travels through space which is full of virtual particles, CBR, and various other little bits of matter :) which probably dont matter too much in the scheme of things. It will be absorbed and reemitted and interact with virtual particles it passes through. Similiar to the way it moves through other materials.Please don't put speculation and New Theories into this section of the forum.
Thank you
We'll answer on this occasion but bear in mind that in future posts may be moved or you could be limited to 'The Lighter Side' ;)
The amount of matter in space is very sparse and the main interactions are scattering and absorption. Even air, which is relatively dense makes only a small decrease in the speed compared to vacuum and to suggest light is slowed significantly by matter – virtual or otherwise – implies very dense matter.
One interesting aspect is dispersion, which occurs when light travels through a medium. This can be seen with pulsars where higher frequencies arrive earlier than lower frequencies which interact with free electrons. However, in the sort of vacuum we see in, say, CERN accelerators, the speed is as close to theoretical as is measurable.
References to virtual particles can be very misleading and are often taken out of context.
I know I keep banging on about people misinterpreting jargon and shorthand terms, but it’s worth reading eg https://www.physicsforums.com/insights/misconceptions-virtual-particles and https://www.physicsforums.com/insights/physics-virtual-particles also https://www.physicsforums.com/insights/vacuum-fluctuation-myth
This is also why virtual photons don’t become real photons in the near field, and why photons can’t ‘bang into’ virtual particles. It’s also why pop science descriptions of the Casmir effect which quote virtual photons are misleading.
Generally the speed of light is thought to be c, but these guys think they might be able to go faster :)Very new theory and 2 separate views. As quoted in the article “Some scientists are a bit skeptical, though. Jay Wacker, a particle physicist at the SLAC National Accelerator Laboratory, said he wasn't confident about the mathematical techniques used, and that it seemed in both cases the scientists weren't applying the mathematical tools in the way that most would. "The proper way to do this is with the Feynman diagrams," Wacker said. "It's a very interesting question [the speed of light]," he added, but the methods used in these papers are probably not sufficient to investigate it.”
https://www.livescience.com/29111-speed-of-light-not-constant.html ;D