1 beda pietanza | in making a new theory cannot be postulated what is patentely false | Friday 17 April 2020 |
2 tjrob137 | Re :in making a new theory cannot be postulated what is patentely false | Friday 17 April 2020 |
3 tjrob137 | Re :in making a new theory cannot be postulated what is patentely false | Saturday 18 April 2020 |
4 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Wednesday 13 May 2020 |
5 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Wednesday 13 May 2020 |
6 Odd Bodkin | Re :in making a new theory cannot be postulated what is patentely false | Wednesday 13 May 2020 |
7 tjrob137 | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
8 maluw...@gmail.com | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
9 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
10 Paparios | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
11 Prokaryotic Caspase Homolog | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
12 maluw...@gmail.com | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
13 maluw...@gmail.com | Re :in making a new theory cannot be postulated what is patentely false | Thursday 14 May 2020 |
14 tjrob137 | Re :in making a new theory cannot be postulated what is patentely false | Friday 15 May 2020 |
15 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Saturday 16 May 2020 |
16 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Saturday 16 May 2020 |
17 Paparios | Re :in making a new theory cannot be postulated what is patentely false | Saturday 16 May 2020 |
18 Kevin Aylward | Re :in making a new theory cannot be postulated what is patentely false | Saturday 16 May 2020 |
19 Nicolaas Vroom | Re :in making a new theory cannot be postulated what is patentely false | Sunday 17 May 2020 |
in making a new theory cannot be postulated what is patentely false
188 posts by 19 authors
https://groups.google.com/forum/#!topic/sci.physics.relativity/o-zNYFUMO74
keywords = Thought experiments, Einstein
They are applied in the theory, in such a way that the first justifies the second and the second justifies the first.
The coincidental correct experimental results don't make them true.
There is a tricky way to use the gamma factor that Lorentz introduced to explain the MMX null result.
The Lorents gamma factor has a math symmetry that can be used wrongly giving at same time correct results.
Some limitate SR results are correct; Though, the SR theorical justification is irrational.
regards beda
> | In SR the two postulate are patentely false. |
Only in the opinion of someone who clearly does not understand the actual issues involved.
> | They are applied in the theory, in such a way that the first justifies the second and the second justifies the first. |
Nonsense!
Indeed, the second postulate is not needed in a modern derivation of SR.
> | The coincidental correct experimental results don't make them true. |
They are not "coincidental"; if the experimental results did not agree with the predictions of the theory, the theory would have been abandoned long ago and you would not need to be so befuddled.
Of course "true" does not apply to physical theories -- at best they are valid with a given domain.
> | [... further nonsense] |
Tom Roberts
> | The photoelectric effect [refutes SR]. |
Hmmmm. I suppose the theory abstracted from Einstein's 1905 paper cannot model the photoelectric effect at all. Ditto for most aspects of atomic theory, most aspects of the standard model, and anything regarding gravitation.
> | It's not *outside* SR's domain: it *contradicts* SR's requirement of wavelike behaviour. |
Hmmmm. Within Maxwell's equations, light is modeled as a wave. That is within the domain of classical electrodynamics; it is far too constricting for SR, which applies to QED (in which light is not at all a wave), and the standard model (which goes far beyond light and electrodynamics, and also has no waves).
So TODAY, the photoelectric effect is outside the domain of SR. It does refute classical electrodynamics (no surprise), but not QED. Nobody really cares how it relates to Einstein's ancient paper (except people who don't know any better).
> | How does SR deal with the photovoltaic effect, Roberts? |
See above. It doesn't.
> | How does [SR] define the wavelength of a single photon? |
See above. It doesn't. Photons are within the domain of QED, not SR.
> | Where is their explanation of the fact that no configuration of test equipment and procedure will produce a light behaviour that mimics the behaviour of sound emergent from a loud hailer? |
In the fact that light is not sound -- DUH! -- they are QUITE different. You REALLY need to learn something about very basic physics.
A major part of your problem is that you simply do not know how to read in the context of modern physics. You are WOEFULLY out of date and seem to not understand the fact that nomenclature morphs over time to fit the needs of the people who use it (not the desires of physics wannabes). "SR" means what we use it to mean TODAY, and not what was thought in 1905.
> | In SR the two postulates are patently false. |
Next, you write:
> | They are applied in the theory, in such a way that the first justifies the second and the second justify the first. |
> | The coincidental correct experimental results don't make them true. |
> | There is a tricky way to use the gamma factor that Lorentz introduced to explain the MMX null result. |
> | The Lorents gamma factor has a math symmetry that can be used wrongly giving at the same time correct results. |
> | Some limitate SR results are correct; Though, the SR theoretical justification is irrational. |
The problem is I also don't like both postulates. IMO to perform science goes in three steps: 1) Observations 2) Experiments 3) Mathematics, Model building and Laws.
Observations always are first. Observations are the starting point to study the behaviour of any process. For example, observations can show regular or stable behaviour, like the movement of the planets around the Sun. The opposite can also be the case: Observations reveal that at certain distinct temperatures water freezes or boils.
The next step is to perform experiments. For me a ground rule of every experiment is to try:
IMO what is important is that when you perform a certain experiment which involves light signals, that you start from the assumption that the speed of light is the same in all directions, locally. That is important because if you move a clock (using light signals) true space and the speed of light varies from place to place you cannot depend on the outcome. This can also give complications if you want to repeat the experiment.
The first postulate relates to different references frames. (plural) Why using different reference frames when you want to study the behaviour of the planets? For some detail see this link: https://www.nicvroom.be/VB%20Planet3d.htm
Why using different reference frames when you want to study the behaviour of a moving clock? The starting point should be a frame in which the speed of light is the same in all directions. Within that frame, you start with two clocks at rest. One of these clocks is placed on board of a rocket and the pilot takes care that the rocket travel from A to B and back to A. When both clocks are back to base they can be compared. Why using two frames in this experiment? What is the advantage?
Using the results of both clocks you can use whatever you want to describe the behaviour in a more mathematical terminology (equation)
The following document also discusses the same issue: https://www.nicvroom.be/The_purpose_of_Science.htm
Nicolaas Vroom
> | On 4/16/20 5:55 PM, beda pietanza wrote: |
> > |
They are applied in the theory, in such a way that the first justifies the second and the second justifies the first. |
> |
Nonsense! |
I agree with you that the above sentence does not make much sense.
> | Indeed, the second postulate is not needed in a modern derivation of SR. |
However, I also have a problem with this sentence. Do you mean that the second postulate is not needed at all in relation to SR? or only in relation to a modern derivation of SR? The second postulate discusses the speed of light and that seems very important in relation to SR, specific in relation to the invariant:
Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated?
Nicolaas Vroom.
> | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
>> | On 4/16/20 5:55 PM, beda pietanza wrote: |
>>> |
They are applied in the theory, in such a way that the first justifies the second and the second justifies the first. |
>> |
Nonsense! |
> |
I agree with you that the above sentence does not make much sense. |
>> |
Indeed, the second postulate is not needed in a modern derivation of SR. |
> |
However, I also have a problem with this sentence. Do you mean that the second postulate is not needed at all in relation to SR? or only in relation to a modern derivation of SR? The second postulate discusses the speed of light and that seems very important in relation to SR, specific in relation to the invariant: ds^2 = dx^2 + dy^2 + dz^2 - c^2dt^2 As I mentioned before: where can I read more about this specific subject. Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated? Nicolaas Vroom. |
I fail to understand the thinking of people who think that there is some squad that ensures that the internet is cleansed of incorrect or misleading information.
For all you lazy boobs who have hopes that physics can be learned from the internet, I have news for you. The internet is a sewer. To find the gold, you have to wade through a thousand times that volume of shit, and what�s the especially problematic concern is that you have to know the difference between gold and shit. And to do that for physics on the internet, this means you already have to know a fair amount of physics to tell the difference between good stuff and crap.
Finally, let�s add a public service announcement that learning a subject from encyclopedia articles, online or not, is a foolish venture.
> | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
>> | Indeed, the second postulate is not needed in a modern derivation of SR. |
> |
However, I also have a problem with this sentence. Do you mean that the second postulate is not needed at all in relation to SR? or only in relation to a modern derivation of SR? |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories:
1. SR, which models the (local) geometry of spacetime.
2. Electrodynamics, which models electromagnetic interactions.
Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1.
Today we understand group theory (which Einstein did not in 1905). We can use group theory to show that there can be only three transformation groups among inertial frames, and that just one of them, the Lorentz group [#], agrees with all the experiments.
So Einstein's second postulate is not needed at all in theory #1 above, SR as understood today by physicists.
[#] Well, the Poincare' group. Which is the same as the inhomogeneous Lorentz group.
> | The second postulate discusses the speed of light and that seems very important in relation to SR, specific in relation to the invariant: ds^2 = dx^2 + dy^2 + dz^2 - c^2dt^2 |
Do not be deceived into thinking that "c" there is the speed of light. IT ISN'T. It represents the invariant speed of the Lorentz group.
Historically, "c" was used to represent the vacuum speed of light, and "c" was also used to represent the invariant speed of the Lorentz group. This has caused countless confusion, but it is only a confusion about history and nomenclature -- the two theories above are distinct and quite clear about the meanings of their symbols.
The remarkable thing is that the two meanings of "c" in those two theories have the same numerical value, established experimentally to high precision (yes, separate sets of experiments).
> | Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated? |
Perhaps. Even probably. I have not looked at it.
Tom Roberts
> | On 5/13/20 11:00 AM, Nicolaas Vroom wrote: |
> > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> >> | Indeed, the second postulate is not needed in a modern derivation of SR. |
> > |
However, I also have a problem with this sentence. Do you mean that the second postulate is not needed at all in relation to SR? or only in relation to a modern derivation of SR? |
> |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories: Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. Today we understand group theory (which Einstein did not in 1905). We can use group theory to show that there can be only three transformation groups among inertial frames, and that just one of them, the Lorentz group [#], agrees with all the experiments. |
Stop fucking, trash. How many times have you written here, at this forum, that coordinates are just an arbitrary human choice? Yes, they are. No "experiments" have ever forced you. It's you responsible for your violating common sense idiocies.
> > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> >> | Indeed, the second postulate is not needed in a modern derivation of SR. |
> > |
However, I also have a problem with this sentence. Do you mean that the second postulate is not needed at all in relation to SR? or only in relation to a modern derivation of SR? |
> |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS. Since then we have found it convenient to split his subject into two separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
Sorry, this is the first time that I read about this split. Who are the people identified as we?
> | Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. |
Why can the second postulate (maybe in a revised form) not be used in theory #2?
> | Today we understand group theory (which Einstein did not in 1905). We can use group theory to show that there can be only three transformation groups among inertial frames, and that just one of them, the Lorentz group [#], agrees with all the experiments. |
I assume that group theory belongs to theory #1. In order to get some understanding I read: https://en.wikipedia.org/wiki/Lorentz_group The first line of that document reads: "In physics and mathematics, the Lorentz group is the group of all Lorentz
transformations of Minkowski spacetime, the classical and quantum setting for all (non-gravitational) physical phenomena." Is that correct?
Which specific experiments do you have in mind? Do you mean twin type like experiments using moving clocks?
> |
So Einstein's second postulate is not needed at all in theory #1 above,
SR as understood today by physicists.
Not all popular articles and elementary textbooks adhere to the separation above. But that separation is necessary to go from SR to GR -- that relies on the invariant speed of SR, and has nothing to do with light. |
The above text mentions that the Lorentz group is non-gravitational. What do you mean with the speed of SR?
> |
> > |
The second postulate discusses the speed of light and that seems very
important in relation to SR, specific in relation to the invariant: |
> |
Do not be deceived into thinking that "c" there is the speed of light. IT ISN'T. It represents the invariant speed of the Lorentz group. Historically, "c" was used to represent the vacuum speed of light, and "c" was also used to represent the invariant speed of the Lorentz group. This has caused countless confusion, but it is only a confusion about history and nomenclature -- the two theories above are distinct and quite clear about the meanings of their symbols. |
First what 'we' did is to declare the 'speed of light c' to be a constant. Secondly, why mention vacuum? Is the space in our solar system considered a vacuum? The concept 'speed of light' is rather clear. Not clear how it is measured. The concept 'speed of Lorentz group' is not clear.
> | The remarkable thing is that the two meanings of "c" in those two theories have the same numerical value, established experimentally to high precision (yes, separate sets of experiments). |
Please can you give a little more detail about these two experiments and what they tried to measure.
Nicolaas Vroom
> > > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> > |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
> |
Sorry, this is the first time that I read about this split. Who are the people identified as we? |
Hundred of thousands physicists who have studied and use SR and GR models.
> > | Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. |
> |
Why can the second postulate (maybe in a revised form) not be used in theory #2? |
Read again, Tom says the second postulate is used in theory 2!!!
> |
Which specific experiments do you have in mind? Do you mean twin type like experiments using moving clocks? |
All the experiments which need the use of SR and or GR models to predict their results.
> | On 5/13/20 11:00 AM, Nicolaas Vroom wrote: |
> > | Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated? |
> |
Perhaps. Even probably. I have not looked at it. |
Wikipedia's article on special relativity definitely sucks, having suffered from the defects of multiple authorship without clear editorial leadership. About 1/3 of the article is my writing, and I sometimes flatter myself into thinking that I am better than the average contributor, but the reality is that I do not currently have the technical expertise to completely re-write sections 6 through 10, which are in pretty foul shape and will probably remain so for an indefinite future. Nor do I have the courage to completely re-write sections 1 through 3, which suffer from too many cooks not having been able to decide whether they were baking a cake or roasting a turkey.
Overall, stay away from Wikipedia, and pick up a good textbook, if you want to learn special relativity.
(I -am- proud of the section on Measurement versus visual appearance.
It was fun doing the animation...)
https://en.wikipedia.org/wiki/Special_relativity#Measurement_versus_visual_appearance
> | El jueves, 14 de mayo de 2020, 9:55:50 (UTC-4), Nicolaas Vroom escribi�: |
> > > > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> |
> > > |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories: |
> > |
Sorry, this is the first time that I read about this split. Who are the people identified as we? |
> |
Hundred of thousands physicists who have studied and use SR and GR models. |
Just studied. Even you(plural) are not stupid enough to use them.
> | On Wednesday, May 13, 2020 at 5:55:50 PM UTC-5, tjrob137 wrote: |
> > | On 5/13/20 11:00 AM, Nicolaas Vroom wrote: |
> |
> > > |
Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated? |
> > |
Perhaps. Even probably. I have not looked at it. |
> |
Wikipedia's article on special relativity definitely sucks, having suffered from the defects of multiple authorship without clear editorial leadership. |
Or rather from following an idiot guru and his idiot minions.
> | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
>> |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
> |
Sorry, this is the first time that I read about this split. Who are the people identified as we? |
Physicists. Basically because this makes sense for the generalization from SR to GR -- light is simply not involved.
>> | Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. |
> |
Why can the second postulate (maybe in a revised form) not be used in theory #2? |
It can.
It cannot be used in theory #1 because it is inherently about electrodynamics, not geometry.
>> | Today we understand group theory (which Einstein did not in 1905). We can use group theory to show that there can be only three transformation groups among inertial frames, and that just one of them, the Lorentz group [#], agrees with all the experiments. |
> |
I assume that group theory belongs to theory #1. |
No. Group theory is mathematics, and can be used in any physical theory, whenever needed. It is essential in the derivation of the equations of theory #1. It is also highly indicative in theory #2, classical electrodynamics, because the Lorentz group is a subgroup of the invariance group of Maxwell's equations (that's how Einstein "lucked out" in 1905, and was able to commingle theories #1 and #2, even though they are really quite different).
> |
In order to get some understanding I read: https://en.wikipedia.org/wiki/Lorentz_group The first line of that document reads: "In physics and mathematics, the Lorentz group is the group of all Loren transformations of Minkowski spacetime, the classical and quantum setting for all (non-gravitational) physical phenomena." Is that correct? |
Yes. Well sort-of -- the Lorentz group does not apply to Minkowski spacetime, it applies to inertial frames _IN_ Minkowski spacetime.
The Lorentz group also applies to locally inertial frames in GR.
> | Which specific experiments do you have in mind? Do you mean twin type like experiments using moving clocks? |
Those, and all others that test SR.
>> |
So Einstein's second postulate is not needed at all in theory #1
above, SR as understood today by physicists.
Not all popular articles and elementary textbooks adhere to the separation above. But that separation is necessary to go from SR to GR -- that relies on the invariant speed of SR, and has nothing to do with light. |
> |
The above text mentions that the Lorentz group is non-gravitational. What do you mean with the speed of SR? |
The INVARIANT speed of SR is the unique speed such that an object moving with that speed relative to one inertial frames moves with that same speed relative to every inertial frame.
>>> | The second postulate discusses the speed of light and that seems very important in relation to SR, specific in relation to the invariant: ds^2 = dx^2 + dy^2 + dz^2 - c^2dt^2 |
>> |
Do not be deceived into thinking that "c" there is the speed of light. IT ISN'T. It represents the invariant speed of the Lorentz group. Historically, "c" was used to represent the vacuum speed of light, and "c" was also used to represent the invariant speed of the Lorentz group. This has caused countless confusion, but it is only a confusion about history and nomenclature -- the two theories above are distinct and quite clear about the meanings of their symbols. |
> |
First what 'we' did is to declare the 'speed of light c' to be a constant. |
Hmmm. In theory #1 c is necessarily a constant, from its definition. The fact that theory #1 is an inherent part of theory #2 is the theoretical justification for the redefinition of the meter in 1983, making 'the speed of light c' to be a constant.
> | Secondly, why mention vacuum? |
Because light only moves with speed c in vacuum (relative to inertial frames).
> | Is the space in our solar system considered a vacuum? |
Yes to high accuracy, but not exactly.
> | The concept 'speed of light' is rather clear. Not clear how it is measured. |
In the usual way: time a light pulse over a known distance, and calculate distance/time. Many undergraduate lab courses do this; it's not difficult to obtain 100 parts-per-million accuracy (but obtaining the much more precise values used in 1983 is much more challenging).
> | The concept 'speed of Lorentz group' is not clear. |
You missed the important word: I discuss the INVARIANT speed of SR. That is unique.
>> | The remarkable thing is that the two meanings of "c" in those two theories have the same numerical value, established experimentally to high precision (yes, separate sets of experiments). |
> |
Please can you give a little more detail about these two experiments and what they tried to measure. |
There are MANY more than two experiments.
To determine the invariant speed of SR, accelerate particles with more and more energy and observe that their speed asymptotically approaches c. Or compare particle travel times to light travel times, as a function of energy.
To determine the vacuum speed of light, measure it in the usual way.
The remarkable thing is that these two VERY DIFFERENT experiments yield the same numerical value: 299792458 m/s.
> | On 5/14/20 8:55 AM, Nicolaas Vroom wrote: |
> > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> >> |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS.
Since then we have found it convenient to split his subject into two
separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
> > |
> >> |
Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. |
What really amazes me that light is not part of SR.
I assume the same is true with GR.
If that is the case I'm not amazed. Newton assumed the same.
> > | Which specific experiments do you have in mind? Do you mean twin type like experiments using moving clocks? |
> |
Those, and all others that test SR. |
But those moving clocks can also use light signals?
> >> | So Einstein's second postulate is not needed at all in theory #1 above, SR as understood today by physicists. |
> > |
The above text mentions that the Lorentz group is non-gravitational. What do you mean with the speed of SR? |
> |
The INVARIANT speed of SR is the unique speed such that an object moving with that speed relative to one inertial frames moves with that same speed relative to every inertial frame. |
IMO that is 'exactly' the same as when the speed of light is considered an invariant.
> >>> | The second postulate discusses the speed of light and that seems very important in relation to SR, specific in relation to the invariant: ds^2 = dx^2 + dy^2 + dz^2 - c^2dt^2 |
> >> |
Do not be deceived into thinking that "c" there is the speed of light. IT ISN'T. It represents the invariant speed of the Lorentz group. Historically, "c" was used to represent the vacuum speed of light, and "c" was also used to represent the invariant speed of the Lorentz group. This has caused countless confusion, but it is only a confusion about history and nomenclature -- the two theories above are distinct and quite clear about the meanings of their symbols. |
> > | The concept 'speed of Lorentz group' is not clear. |
> |
You missed the important word: I discuss the INVARIANT speed of SR. That is unique. |
Sorry, above you used both.
When you do a search with: "Invariant speed of SR" (within "") there is only one hit https://www.physicsforums.com/threads/deriving-speed-of-light-from-qed.775955/ When you do a search with: Invariant speed of Lorentz group you get articles which mention the speed of light.
> >> | The remarkable thing is that the two meanings of "c" in those two theories have the same numerical value, established experimentally to high precision (yes, separate sets of experiments). |
> > |
Please can you give a little more detail about these two experiments and what they tried to measure. |
> |
There are MANY more than two experiments. To determine the invariant speed of SR, accelerate particles with more and more energy and observe that their speed asymptotically approaches c. |
I always thought that when particles are accelerated their final speed is the speed of light
> | Or compare particle travel times to light travel times, as a function of energy. |
I don't understand. How do you do that?
> | The remarkable thing is that these two VERY DIFFERENT experiments yield the same numerical value: 299792458 m/s. |
I assume the first question to answer is: What is the physical meaning of "The (invariant) speed of SR"?
> | El jueves, 14 de mayo de 2020, 9:55:50 (UTC-4), Nicolaas Vroom escribi�: |
> > > > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> |
> > > |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS. Since then we have found it convenient to split his subject into two separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
> > |
Sorry, this is the first time that I read about this split. Who are the people identified as we? |
> |
Hundred of thousands physicists who have studied and use SR and GR models. |
The question is what exactly have they studied.
What they should have studied is a physical process and not a model.
And the way to study is by means of experiments not thought experiments.
1) Newton studied the movement of the planets around the sun.
The results you can see at this link:
https://www.nicvroom.be/VB%20Planet3d.htm
To try to do the same using GR is I think very complicated.
2) A physical process can also be a clock.
You can study that more or less on its own at rest or moving.
A typical clock to study is a clock using light signals.
But generally speaking, this has nothing to do with SR.
> > > | Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. |
> > |
Why can the second postulate (maybe in a revised form) not be used in theory #2? |
> |
Read again, Tom says the second postulate is used in theory 2!!! |
> > | Which specific experiments do you have in mind? Do you mean twin type like experiments using moving clocks? |
> |
All the experiments which need the use of SR and or GR models to predict their results. |
And how do you know that an experiment needs SR or GR? The problem is that Newton's theory was not accurate enough to predict the trajectory of Mercury. His major 'problem' was that he assumed that the speed of gravity acts instantaneously. That was 'wrong'. In order to explain the behaviour of a clock using light signals, the only assumption is that locally the speed of light is the same in all directions. My assumption would be, that when you want to study any physical process, only to use one reference frame. That makes everything much easier.
Please read:
1) https://www.nicvroom.be/The_purpose_of_Science.htm
This document discusses processes which require light
2) https://www.nicvroom.be/Celestial_Mechanics_from_Start_to_Finish.htm
This document discusses processes which don't require light
Nicolaas Vroom
> | On Thursday, 14 May 2020 16:37:31 UTC+2, Paparios wrote: |
> > | El jueves, 14 de mayo de 2020, 9:55:50 (UTC-4), Nicolaas Vroom escribi�: |
> > > > > | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
> > |
> > > > |
First remember that Einstein's 1905 paper was about ELECTRODYNAMICS. Since then we have found it convenient to split his subject into two separate theories: 1. SR, which models the (local) geometry of spacetime. 2. Electrodynamics, which models electromagnetic interactions. |
> > > |
Sorry, this is the first time that I read about this split. Who are the people identified as we? |
> > |
Hundred of thousands physicists who have studied and use SR and GR models. |
> |
The question is what exactly have they studied. What they should have studied is a physical process and not a model. And the way to study is by means of experiments not thought experiments. |
You know nothing of how physics is studied or used!!
In 1905, Einstein used the result of a well know experimental result, to formulate the Special Relativity model (contained in the first 5 sections of his paper). The second part of his paper (sections 6 to 10) addresses the Electrodynamics results.
> > | All the experiments which need the use of SR and or GR models to predict their results. |
> |
And how do you know that an experiment needs SR or GR? |
All physics models have a domain of applicability.
Newtonian Mechanics is very good model to apply when speeds and gravity are very low.
Special Relativity is a very good model to apply when speeds are very high and gravity is very low.
General Relativity is a very good model to apply when speeds and gravity are very high.
Quantum Electrodynamics is a very good model to apply when objects are very very small.
There is no available model which can be applied to all conditions found in Nature.
Since we do not yet have devices which can travel at 100000 km/sec or placing instruments near a black hole, we need to use experiments which use our available devices (planes, rockets, atomic clocks, linear accelerators, etc.) to perform experiments which serve to validate our physical models.
On 5/14/20 8:55 AM, Nicolaas Vroom wrote:
> | On Friday, 17 April 2020 02:49:37 UTC+2, tjrob137 wrote: |
>> | First remember that Einstein's 1905 paper was about ELECTRODYNAMICS. Since then we have found it convenient to split his subject into two separate theories: 1. SR, which models the (local) geometry of spacetime. |
>>> | Today we understand group theory (which Einstein did not in 1905). We can use group theory to show that there can be only three transformation groups among inertial frames, and that just one of them, the Lorentz group [#], agrees with all the experiments. |
> |
>> |
I assume that group theory belongs to theory #1. |
> | No. Group theory is mathematics, and can be used in any physical theory, whenever needed. It is essential in the derivation of the equations of theory #1. |
Oh dear....
You really like to get on that pretentious high horse Tom.
You claim that group theory is "essential", yet also state Einstein did not understand it in 1905. Ahmmm.....
er.... no, group theory is not "essential" to derive the equations of SR. No standard derivation of SR uses group theory, explicitly.
Sure, it might give a tad more of an insight, but whatever...
-- Kevin Aylward http://www.kevinaylward.co.uk/gr/index.html http://www.kevinaylward.co.uk/qm/index.html
> | On Wednesday, May 13, 2020 at 5:55:50 PM UTC-5, tjrob137 wrote: |
> > | On 5/13/20 11:00 AM, Nicolaas Vroom wrote: |
> |
> > > |
Should this link: https://en.wikipedia.org/wiki/Special_relativity not be updated? |
> > |
Perhaps. Even probably. I have not looked at it. |
> |
In the document https://en.wikipedia.org/wiki/Time_dilation we read:
"2.1 Simple inference of velocity time dilation"
"Time dilation can be inferred from the observed constancy of the speed of
light in all reference frames dictated by the second postulate of special
relativity."
This is wrong because:
>> | Einstein's second postulate involves light, putting it FIRMLY in theory #2. So it cannot be used in theory #1. (i.e) Electrodynamics |
> | Wikipedia's article on special relativity definitely sucks, having suffered from the defects of multiple authorship without clear editorial leadership. |
> | Overall, stay away from Wikipedia, and pick up a good textbook, if you want to learn special relativity. |
That is the question. What is a good textbook?
> | (I -am- proud of the section on Measurement versus visual appearance. It was fun doing the animation...) |
https://en.wikipedia.org/wiki/Special_relativity#Measurement_versus_visual_appearance
This paragraph starts with the sentence:
"Time dilation and length contraction are not optical illusions, but genuine
effects."
The problem is 'Time dilation' is a real physical effect. Identical clocks
under certain circumstances can run slower, which can be observed at the
end of an experiment.
'length contraction' is not a real physical effect. It can not be observed
at the end of an experiment.
'length contraction' is a temporary effect, it is an illusion. The name is
wrong because it also includes 'length expansion'.
Next is written
"Scientists make a fundamental distinction between measurement or observation
on the one hand, versus visual appearance, or what one sees."
That is a very misleading statement.
The issue is what we see of the world versus the way the world actually is.
The world is a 3D something of 'infinite' size which changes in 'time'.
What we see is an image of this world in the 'past'.
What we see are objects at a distance which we observe as being smaller than
they really are.
What we see are also objects approaching and retreating. Those objects even
seem to be changing in size. This becomes the best visible when the moving
object all of a sudden stops.
To get an idea what is involved please study this document:
https://www.nicvroom.be/VB%20Train%20operation.htm
This document gives a lot of detail about the physics involved.
Nicolaas Vroom
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