xyzt

 

Sorry, who are you attributing this quote to?

It is a paraphrase to md65536's claim that :

Meanwhile the observer at the front of the train observers local time passing normally, while other coordinate times jump (backward).

Strange is right.

 

Remember the twin paradox. When the accelerating twin changes inertial speed, the coordinate time of the distant twin that it accelerates toward jumps forward (only relative to a local clock). The coordinate time of a twin that is accelerates away from jumps backward. The "jump" is merely a change in relative simultaneity.

This has nothing to do with acceleration or with the twin paradox. Please stop confusing people with your misinterpretations.

 

What is correct then?

[math]t'=\gamma(t-vx/c^2)[/math] tells you that the coordinate time is a function of BOTH time AND location. This doesn't mean that "the clock in the front slows down more than the clock in the rear".

Therefore, they must conclude that the one at the front slowed down relative to themselves more than the one at the rear.

No, this is an incorrect conclusion.

Thanks everyone for your answers.

I guess I'm still confused. I'm just wonder why "the middle" should be considered to be exactly mid-way between the two trains.

If you look at the math in my answer to you , you will realize that "middle" is a frame-dependent notion, it means one position in the frame of the train and a DIFFERENT position in the frame of the track.

If these two events--the front of the train and the rear passing by a certain point--occur closer in time than they would according to a Newtonian perspective, then one can only conclude that the length of the train must also be less than it would according to a Newtonian perspective.

Correct, this is a manifestation of length contraction. It is responsible for us being able to "cram" more particles in a particle accelerator than predicted (and allowed) by Newtonian mechanics. Special Relativity trumps Newtonian mechanics.

 

A friend asked an interesting question about length contraction that I didn't know the answer to: as we know, the faster an object travels, the more it's length contracts. But what happens when you have two objects travelling, one behind the other, at the same rate at the same time? For example, two trains on a track, one behind the other, and they both start moving at the same rate at the same time. What is the center point around which length contraction occurs. Does each train contract around its own center, or can both trains be considered one object and their collective length contracts around the mid-point between them?

Another way of asking this is: what counts as an "object" in relativity?

 

To put swansont's post into math:

An object of length [math]L[/math] is located at distance [math]d[/math] from its frame of reference. So , its extent is [math][d, d+L][/math].

In another frame, moving at speed [math]v[/math] wrt the object, its extent is given by the Lorentz transforms, so the extent is:

[math][d \sqrt{1-(v/c)^2}, (d+L) \sqrt{1-(v/c)^2}][/math].

So, the object distance to the origin of the system of coordinates contracts just as its length.

A train can be described as:

[math][(d_1, d_1+L_1),(d_2, d_2+L_2)][/math] in its co-moving frame. In the moving frame, the train is described as:

[math][(d_1, d_1+L_1)\sqrt{1-(v/c)^2},(d_2, d_2+L_2)\sqrt{1-(v/c)^2}][/math]

Many thanks mate hard copies on order

 

http://www.amazon.com/Relativity-Experimental-Foundations-Advanced-Theoretical/dp/9810227493

Lol add that to my 20+ collection of physics related books.

 

Ps my wife always asks "Why are you so interested in this universe stuff, you will never go there"

 

My response " I'm already there"

 

After 15 years she still doesn't get it lol

Looking over some of the reviews his take on the one way vs two way influences on photons may or may not provide insight beyond what I already understand. Knowledge is always good regardless of perspective.

You are welcome, it is a good book.

Makes it even more motivating for me to study his work. Any particular article recommendations? ( no limit on technicality)

 

I've always been a firm believer in learning how our models developed historically. This includes major counter theories.

I can do better than that, the whole story of the development of the test theories of SR is explained extremely well in this book:

Y.Z. Zhang, Special Relativity and its Experimental Foundations, World Scientific (1997)

Thanks for sharing that zyxt, I'll have to study that bit of history in more detail.

It is fundamental to the contemporary state of SR.

 

Thanks - I never knew the story of Ives. Shows the magnificence of our scientific method - and a great deal of personal intellectual integrity - that such an experiment by a firm believer in an alternative explanation can still be used to bolster Einstein's explanation.

 

Lovely and quite sad quote from his friend H P Robertson

 

 

http://en.wikipedia.org/wiki/Herbert_E._Ives

Yes, it is a fantastic story of integrity.

As an aside, we owe to H.P.Roberson the first test theory of SR. One can say that Robertson was for (the) theory (of SR) what Ives was for the experimental test. It was Ives insistence on testing SR that inspired Robertson to create the theoretical framework for the test theories of SR. To date, the Ives-Stilwell experiment is a pillar (together with MMX and KTX) of the test theories of SR. It was Robertson as well who proved that the three tests are the necessary and sufficient set.

 

 

Yeah - understanding the transverse doppler effect is a real work-out that tests your understanding of relativity; at the point of closest point of approach of two objects light received will be blue-shifted but light emitted will be red-shifted. This was a major new testable prediction of special relativity

 

http://en.wikipedia.org/wiki/Relativistic_Doppler_effect#Transverse_Doppler_effect

Correct, it is the foundation of the Ives-Stilwell experiment, one of the most stringent tests of SR.

Einstein conceived it and Herbert Ives, despite of being a convinced anti-relativist, executed it.

Keep in mind there are variations on the formulas for reasons such as transverse redshift etc.

 

(Transverse different angles ie object moving left to right at different angles)

"Transverse redshift" is simply a forme of Transverse Doppler Effect which, BTW can be EITHER redshift or(!) blueshift. There is an angle, called critical angle, for which there is zero shift, at the boundary between red and blueshift.

My understanding of red shift is that objects moving away from an observer take on a red shade because the photon's frequency is reduced and wavelength is increased (stretched) as it travels from the moving object towards our eye (the distance between the two grows as the photon travels at us)...And being in front, one would see a blue shift as the photon's frequency is increased (compression)...cuz the distance between the 2 objects is getting smaller as it approaches us...so expanding space would be seen with a red shift, and compressing space is seen as blue

 

We also see redshift in objects with massive gravity as well...in comparison to the above, gravity would also then represent an increase in the wavelength of light. And imply that objects with more gravity are moving away from us in this relative comparison of the effects of motion on space-time and the effects of gravity on space-time.

 

And it doesnt make much sense to me to think of gravity as a "separation" of objects...that would imply an acceleration away from two objects...but gravity seems to imply an acceleration of objects towards each other...

 

How does one get RED when the force of gravity would seem to imply a shrinking of space between 2 objects...and we know we see red when 2 objects are increasing the space between them? not shrinking it...

 

I know we do get red, but doesnt this imply that 2 objects within a common gravitational field would be seen as falling away, not together? Falling together seems to create a blue shift...

 

SO im stumped...

You are mixing gravitational redshift with cosmological redshift. The former is created by the difference in gravitational potential, the latter is created by the increased separation between emitter and receiver (it is similar but not identical to Doppler redshift).

 

Your jest is not at all appreciated. Of all places, I thought the best reception for this discovery would be here.

There is no "discovery". There is plenty of delusion, though.

sigh.

 

Your answer is no more logical than any of the others. Unless, of course, you are using the usual "personal theory" meaning of logic, which appears to be "it makes sense to me because I thought of it".

 

Clearly you have not read any of the thread. That couldn't be further from the truth.

I cannot fix delusions.

 

Very recently, CERN made a stunning announcement. They had detected particles traveling beyond the speed of light.

No, they didn't, it was an experimental setup error,a disconnected cable. You need to stop the nonsense about "relativity is wrong".

He exposed a very sympathetic low profile for a new member.

I was simply echoing the reaction of another member. Maybe you can give him a "-1" as well. I dare you.

JCJ posted

 

What's wrong with that?

 

OTOH your post XYZT was very offensive. -1 for that. I mean BS is coming out of your mouth, if you don't understand what offensive means.

Fringers always support other fringers. I interacted enough with you to know that.

General Relativity? Ohw, I’m not going to argue with Einstein’s theory expect for one thing. Its not complete, it does give us many wonderful things but does not explain everything its missing something still.

 

 

 

In other words it is too difficult for you to study so you are replacing the studying with your make believe BS. Posting BS is a much easier feat than studying.

 

What you're doing isn't thinking outside the box, it's peeing all over the outside of the toilet, simply because it's too much work to aim at the insides.

I will have to steal the above, it is a brilliant characterization.

For people who are too comfy inside the box, it is obviously unsettling to see some out of box stuff.

Not at all. Your "outside the box" is pure horse manure. Stop deluding yourself claiming that it is science.

All I am suggesting is that some of the branches of science today have become 'unscientific'.

The standard ignorant crank claim: "I don't understand it, therefore it must be wrong".

Let's focus on this topic. If you have proof then present it here,

Err, the burden of proof is on you. You made the BS claims.

Good science starts that way, sometimes. i.e. it was started by 'ludicrous' idea and proved/disproved by people who had more time than what they know how to spend. Thinking out of box is my job.

Posting made up garbage does not qualify as "thinking out of the box".

You sound awfully like my friend Alan M. I appreciate his scientific rigor. But what I want is to get something new, interesting or helpful from a debate.

Random crank claims do not constitute a debate.

There is some confusion about the S radius and the event horizon location....in this paper,

 

http://thep.housing.rug.nl/sites/default/files/theses/Bachelor%20thesis_Pieter%20van%20der%20Wijk.pdf

 

On page 34 it shows the event horizon INSIDE the mass (stationary surface limit)...how could you ever get to the event horizon if it was within the object?

.

 

Well, the Earth's Schwarzschild radius is 9 mm. It is tough that you don't understand basic physics.

We can ban me from the forum for not understanding the math, or ban me for not forcing myself to examine the math to create an understanding...but really fellas...in a conversation where someone doesnt understand math, you cant get very far in communicating with that person in math...so you have to find another means or stop trying...i dont try to have conversations with monkeys...and I dont get mad at them for not being able to understand my language...i just walk away..

Goo idea.

 

Im going to study the math...i allready have begun...should i just come back after that? itll be like four years...or can we still have a discussion that includes a language that I understand?...

Yes, come back after you learned.