The Point - Extension conundrum

Ideas and innovations in Indian classical music
shankarank
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#26 Re: The Point - Extension conundrum

Post by shankarank » 06 Jan 2018, 05:33

Found another article ; An interview of Prof Alladi Ramakrishnan - a music connoisseur who defines an event ( or a point) using extensions (rods) or crossing of two rods to solve some anomalies in the understanding of Lorentz equations - he says that he found after 56 years in the field.

http://www.rediff.com/news/aug/18alladi.htm
Why is it that even after 90 years, no scientist could clear the confusion?

I will tell you why the confusion arose. That is because the word 'event' has not been defined at all. The great Einstein himself did not define 'event'. He just said something happens at a particular point in space at a particular time and that is an 'event'. The 'event' is defined by the space and time co-ordinate only. But nobody cared to explain what the 'event' was, because mathematically it is defined by 'X' and 'time' co-ordinates.

The Lorentz transformation explains how 'X' and 'T' change, so people all over the world thought why you should know what the 'event' is. It may be the birth of a particle or the death of a particle, it may be anything. That is the reason why they did not solve the problem.

How could you solve the problem, that too after 56 years?

Yes, I will tell you how I solved it. I have been thinking of this problem for 56 years. It was only last year that the solution came to my mind, that too in a flash. You may ask, why did it take 56 years? The answer is very clear. Because once you know the solution, you will understand why this has eluded me till now. See, it is like having a bunch of 10,000 keys and all of them are almost alike but one of them alone is the correct key. How would you trace it?

You have to try out all the keys one by one?

See, it is almost impossible, is it not? That is why it took 56 years for me. It also took a lot of time before I had the courage to say that by 'event' you always mean the crossing of two points. When one point is moving against another, the crossing of the points is what is called an 'event'. Any 'event' which you see in the world can ultimately be interpreted as the crossing of two points. After 92 years, for the first time the word 'event' has been defined as the crossing of the points.

Now, why do points cross? I added one more idea. That is, every point is the end of a rod. Therefore, the fundamental concept is the crossing of rods rather than crossing of points. Once you start in terms of rods which are crossing, we understand the changes and all problems are simultaneously solved.

How did you come to the conclusion that points are not just points alone but they lie at the ends of rods?

That is because a point is always included in a rod as it is the end point. But a rod concept is not included in a point. A rod is a much better concept because according to Einstein, a rod shrinks when it moves, the shrinking will not be there if you are only thinking of a point. So, you must think of the rod as a fundamental quantity and not a point.

What I did was, I took two rods, one stationary and the other moving. What I now say is, the moving rod has the same length as the stationary rod. This is the newest idea put forward in 92 years. Nobody in the history of physics has ever thought that a moving rod can have the same length as the stationary rod.

People know that when two rods of equal length move, they contract. But what they did not think of was a moving rod has the same length as a stationary rod. When such a crossing occurs, the end points are coincident simultaneously because the lengths are equal. But if you sit on the moving rod, that rod will look stationary while the other rod which was originally stationary now looks moving.
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uday_shankar
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#27 Re: The Point - Extension conundrum

Post by uday_shankar » 07 Jan 2018, 00:11

Beautiful. Thanks for sharing. Alladi Ramakrishnan was a class act. They don't make them like that anymore :(.
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sureshvv
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#28 Re: The Point - Extension conundrum

Post by sureshvv » 07 Jan 2018, 10:25

shankarank wrote:
06 Jan 2018, 05:33
Found another article ; An interview of Prof Alladi Ramakrishnan -

http://www.rediff.com/news/aug/18alladi.htm

What I did was, I took two rods, one stationary and the other moving. What I now say is, the moving rod has the same length as the stationary rod. This is the newest idea put forward in 92 years. Nobody in the history of physics has ever thought that a moving rod can have the same length as the stationary rod.

People know that when two rods of equal length move, they contract. But what they did not think of was a moving rod has the same length as a stationary rod.
Seems like a contradiction. Can someone(uday?) explain?
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shankarank
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#29 Re: The Point - Extension conundrum

Post by shankarank » 07 Jan 2018, 11:45

Well I understood it as when two rods of equal length move in relation to each other, they both appear contracted exactly to the same length as viewed from an observer on each rod, when viewed from the reference frame of the other. And they both align at some time when they pass each other, there is simultaneity of two observers who are in motion relative to each other, at the end point, as they are co-located briefly in both space and time.

That defines a point in space time.
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sureshvv
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#30 Re: The Point - Extension conundrum

Post by sureshvv » 07 Jan 2018, 12:23

If moving rod contracts, how can it have same length as stationary rod?
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shankarank
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#31 Re: The Point - Extension conundrum

Post by shankarank » 07 Jan 2018, 23:48

Well you have to now posit a third observer that moves at a different speed in relation to these two rods. Lets assign some numbers now.

Lets say the relative speed between the two equal length rods is 4. I.e. for two observers , each attached to these two rods the velocity ( which has directionality attached to it unlike speed which is the absolute value) is +4 and -4 from each of the other rods. For one the other is moving in a positive direction and vice-versa for the other the first is moving in the opposite direction.

Lets say there is a third observer who is moving at +2 in relation to one of the rods (first rod), his speed will be -2 with respect to the second rod. And for simplicity we reduce it to a one-dimensional space and time, where the rods are extended along just one dimension - all 3 of them.

https://en.wikipedia.org/wiki/Length_contraction

Since the "v" there is squared the direction does not matter and hence, for the third observer both of them are equally contracted. So lets say there is a light source attached to the end point ( of both the rods) emits a light from both rods at the time they are aligned, it will reach the third observer at the same time, since speed of light is experimentally known to be a constant - "c". So that is a simultaneous event in two reference frames. A light emitted from the other ends will reach this third observer with SAME delay or ahead ( depending on the relative placement of the 3rd observer) , making him conclude that they are of both the same length.

So the points ( events in space-time) are now experimentally observed.

We also have to remember that this is special relativity, an idealized model where there is no gravity, no masses to cause any acceleration. Now don't ask me how an observation can be made , since observing a photon requires an absorption by a massive particle. Again these are thought experiments (gedankan experiment) in an idealized model. If you carefully observe the formula for contraction there is no mass in it. Also Prof. Alladi Ramakrishnan is a mathematical physicist! ;)

And reference frames are defined ( I mean they are deemed different) only due to a non-zero relative speed between themselves. I.e. any observer that is stationary with respect to the other is in the same reference frame.

Hence the term relativity.
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