Why in the world would Einstein suggest....

@Thomas,

Quote:

I'm not saying this is a conventional view, only that it violates no physical laws.

Not the law of conservation of momentum, or anything? Who knew?

1. I want to go downtown.
2. I go out to my car and start the motor.
3. Then I push down on the gas pedal.
4. That action causes the earth to start moving, bringing downtown to me.
5. No matter that the guy on the other side of town, who also desires to bring "downtown" his way, does the same thing, at the same time, which then causes the earth to start moving toward him (and away from me).

2 Replies

@layman,

layman wrote:

Quote:
I'm not saying this is a conventional view, only that it violates no physical laws.

Not the law of conservation of momentum, or anything?

No.

1 Reply

@Thomas,

Quote:

No.

OK, Thomas. I want to thank you for the discussion. You are the first one who has actually made an effort to discuss and defend, rather than merely LOUDLY assert, his notions about SR and "motion."

I'll just consider this discussion over, with us "agreeing to disagree," unless maybe you want to elaborate on the simple "no" you just gave, and respond to the points I made which I think disfavor your negative assertion.

0 Replies

@Thomas,

Quote:

Physical experiments that test physical theories are the only source of knowledge about physics.

One more comment, since I had overlooked this assertion that you made.

Are you aware that the postulates of SR are considered to be "untestable?" That is to say that there is no known way to "falsify" the theory. If you accept it's premises, the conclusions follow. But alternate, opposite premises give the exact same conclusions. Those theories really can't be "tested" (against SR, I mean) either. If you accept the premises of those theories, then, once again, the conclusions follow (by definition, just like SR). There is no known way to empirically distinguish between SR and AST (absolute simultaneity theories). To the extent that any given experiment is said to "confirm" SR, then it, to that same extent, also "confirms" the AST.

Quote:

Mansouri and Sexl spoke about the "remarkable result that a theory maintaining absolute simultaneity is equivalent to special relativity."

http://en.wikipedia.org/wiki/Test_theories_of_special_relativity

1 Reply

@layman,

layman wrote:

3. Then I push down on the gas pedal.

At which point your car's motor converts chemical energy into mechanical energy, which your car's wheels transmit onto the road. A this point, the car-Earth system is no longer closed, and the conservation of momentum only applies to closed systems. But I don't want to rely on technicalities like that, so let's move on.

layman wrote:

4. That action causes the earth to start moving, bringing downtown to me.

No it doesn't. In your car's frame of reference, the Earth's center of mass always remains exactly where it was before --- about 4,000 miles straight down from your car. In your car's frame of reference, then, the total momentum of the car-Earth system was conserved at the value of zero.

1 Reply

Sorry if this isn't what you meant:

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

Quote:

What is the experimental basis of Special Relativity?

There has been a renaissance in tests of Special Relativity (SR), in part because considerations of quantum gravity imply that SR may well be violated at appropriate scales (very small distance, very high energy). It has been seven years since the last update of this page, and there are over 60 new experiments, many of which are recent, ingenious, and improve bounds on violations of local Lorentz invariance by several or many orders of magnitude. To assist the reader in finding the updates, major changes to this page are in dark blue (tagged with <ins> in HTML).

Introduction
Domain of Applicability
Test Theories of SR
Optical Extinction
Early experiments (Pre-1905)
Roentgen, Eichenwald, Wilson, Rayleigh, Arago, Fizeau, Hoek, Bradley, Airy.
Tests of Einstein's Two Postulates
Round-Trip Tests of Light Speed Isotropy
Michelson and Morley
Kennedy and Thorndike
Modern Laser/Maser Tests
Other
One-Way Tests of Light Speed Isotropy
Cialdea, Krisher, Champeny, Turner & Hill.
Tests of Light Speed from Moving Sources
Cosmological Sources: DeSitter, Brecher
Terrestrial Sources: Alvaeger, Sadeh, ...
Measurements of the Speed of Light, and Other Limits on it
NBS Measurements, 1983 Redefinition of the Meter
Limits on Variations with Frequency
Limits on Photon Mass
Tests of the Principle of Relativity and Lorentz Invariance
Trouton Noble
Other
Tests of the Isotropy of Space
Hughes-Drever, Prestage, Lamoreaux, Chupp, Phillips, Brillet and Hall.
Tests of Time Dilation and Transverse Doppler Effect
Ives and Stilwell
Particle Lifetimes
Doppler Shift Measurements
Tests of the Twin Paradox
Hafele and Keating, Vessot et al., Alley, Bailey et al.
The Clock Hypothesis
Tests of Relativistic Kinematics
Elastic Scattering
Limiting Velocity c
Relativistic Mass Variations: electron, proton
Calorimetric Test of SR
Tests of Length Contraction
Magnetic Force
Recent Tests of CPT and Lorentz Invariance
Many Ingenious and Precise experiments of different types
Other Experiments
...

Also, a "test theory" has a different meaning from "testing a theory."

http://en.wikipedia.org/wiki/Test_theory

1 Reply

@layman,

layman wrote:

Are you aware that the postulates of SR are considered to be "untestable?"

No, because SR is refutable. For example, muons at relativistic speeds would have refuted it if they didn't live far longer than muons at rest. But they do, so they haven't.

1 Reply

@Thomas,

Quote:

At which point your car's motor converts chemical energy into mechanical energy, which your car's wheels transmit onto the road

Are you saying, then, that the car, rather than the earth, begins to move at that point? How much gas does it take, I wonder, to cause the earth to commence into motion?

1 Reply

@FBM,

Thanks FBM! Your list is much better than what I came up with.

1 Reply

@Thomas,

This reply is also to FBM.

I already said two things in my post that may have been overlooked, to wit:

1. That SR is not testable as against an AST (or vice versa), and
2. Any test which is said to confirm SR also confirms an AST.

I note that your post did not seem to acknowledge point #2, FBM. It is just such "omissions" that lead some people to think that SR has been "proven."

1 Reply

@Thomas,

I can't do science for ****, but I can google with the best of 'em!

0 Replies

@layman,

layman wrote:

Quote:
At which point your car's motor converts chemical energy into mechanical energy, which your car's wheels transmit onto the road

Are you saying, then, that the car, rather than the earth, begins to move at that point?

It does accelerate, I'll give you that.

layman wrote:

How much gas does it take, I wonder, to cause the earth to commence into motion?

Since the car's acceleration is perpendicular to the vector pointing from the car's center of gravity to the Earth's center of gravity, no amount of gas will ever move planet Earth, as observed in the car's frame of reference. Perhaps you want to craft an argument around angular momentum rather than momentum.

1 Reply

@layman,

layman wrote:

1. That SR is not testable as against an AST (or vice versa), and

Which AST model do you have in mind? If it's the Galilean model, the muons do refute it in favor of special relativity because the Galilean transformation predicts an equal lifetime of relativistic muons and muons at rest. If it's not the Galilean model you have in mind, then what model do you have in mind? You can't beat something with nothing, and if all you offer is some vague, abstract notion of "a AST", that's nothing.

1 Reply

@Thomas,

Quote:

...no amount of gas will ever move planet Earth, as observed in the car's frame of reference.

So, are you saying then, that, from the car's perspective, IT is moving, not "downtown?"

If so, then this is the type of claim that Prof. Morin says would cause a "complete disaster" for SR. Let's say the car, heading downtown, first hits the freeway and accelerates to 60 mph, then holds that steady speed for 3-4 minutes. At THAT point, does the fact that he is holding the gas pedal down in one place, suddenly "cause" the earth to start moving? Or is the car still moving, from it's frame of reference?

1 Reply

@Thomas,

Quote:

Which AST model do you have in mind?

The one I had in mind was the one used by Mansouri and Sexl. Remember those guys?

Quote:

Mansouri and Sexl spoke about the "remarkable result that a theory maintaining absolute simultaneity is equivalent to special relativity."

You can read all about the one they used here.

http://en.wikipedia.org/wiki/Test_theories_of_special_relativity

If that's not sufficient, I believe wiki has a clickable reference to their massive, 3-part study, which elaborates in great length about the test theory used, and their findings.

As I recall, they used the CMBR as the "standard" against which relative motion (and therefore time dilation) was assessed.

1 Reply

@layman,

layman wrote:

If so, then this is the type of claim that Prof. Morin says would cause a "complete disaster" for SR.

No, because Morin's remarks presume an inertial system --- in particular, a train moving at constant speed relative to the rails. By contrast, an accelerating car is not an inertial system.

1 Reply

@layman,

layman wrote:

The one I had in mind was the one used by Mansouri and Sexl. Remember those guys?

I have no reason to, unless you can tell me how their model explains why the relativistic muons live longer than the resting ones.

1 Reply

@Thomas,

Quote:

No, because Morin's remarks presume an inertial system

You must have missed this part of my question, Thomas:

Quote:

Let's say the car, heading downtown, first hits the freeway and accelerates to 60 mph, then holds that steady speed for 3-4 minutes. At THAT point, does the fact that he is holding the gas pedal down in one place, suddenly "cause" the earth to start moving? Or is the car still moving, from it's frame of reference?

1 Reply

@Thomas,

Quote:

I have no reason to...

Suit yourself. A typical response from SR advocates, from my experience.

I can tell you, generally speaking, that, from what I understand, the AST used by them was, in their words, very similar to the one used by Henrik Lorentz (who Al took his transformations from). Both theories assume that time slows down with speed. And that is all SR advocates are claiming insofar as they claim that the muon thing "confirms" it.

1 Reply

@layman,

layman wrote:

Or is the car still moving, from it's frame of reference?

At this point, the car is standing still from its frame of reference. Downtown is moving.

1 Reply

Why in the world would Einstein suggest....

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