# I don't understand Theory of Relativity: A)I am not clever B)Nothing to understand

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Thanks Strange. If you want to organize an event you don't need time, you just use time as tool. You don't need a when, but it would be better to say that you use a when, just to keep track and calculate the movements.

Does that mean you don't need a where, either? You just use the place as a tool. You don't need a where, but it would be better to say that you use a where, to keep track and calculate the movements.

To prove that you are wrong: I will meet you at Hyde Park Corner in London and give you a million pounds. (I am pretty sure my money is safe.)

Two objetcs cannot occupy the same space because they collide with each other, no matter when.

Nonsense. Otherwise you would be knocked down by traffic even when crossing a now empty road.

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I think he considers on object to be fixed and then for all time you cannot place another object at the same location as the first object. Rather than fix a location...

Right. You know what I mean.

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How is this fundamentally different to the concept of length as a measuring tool (we assign some units to length) and a human idea?

This is a great question, and I hope to answer it well: length as a measuring tool is exatcly like time, it will never be perfect, it will always be an approximation of reality, so there is no difference between measuring space or measuring movements. Space is the only dimension, and we measure it with our human concepts of height, length and width. Many ideas exist only in our imagination and fantasy, but they don't exist in reality. Space, matter and movement, not only exist in our mind, but they exist in reality as well. However, the idea of perfect measurements, or the idea of two identical unities, don't exist in reality, but only in our minds, and thanks to this idea, we can have math and measurements, so we can write 1=1, and we can measure everything, and we can agree more or less on these measurements. Measurements will never be perfect, they will never represent perfectly reality. Whatever you use to measure length in space, you need a material tool, like a tape, or a laser. A tape can be made of steel, plastic or whatever you want, but one meter long tape, will never be exactly one meter long, it will be only an approximation of one meter. A perfect meter long object is only in our fantasy.

Whatever we calculate and measure (length, movement, speed), it's only an approximation, because matter it's not stable at all, it's constantly changing and moving, because its atoms are always changing and moving, even if we don't see it. Measuring doesn't give life to anything.

Does that mean you don't need a where, either? You just use the place as a tool. You don't need a where, but it would be better to say that you use a where, to keep track and calculate the movements.

To prove that you are wrong: I will meet you at Hyde Park Corner in London and give you a million pounds. (I am pretty sure my money is safe.)

Nonsense. Otherwise you would be knocked down by traffic even when crossing a now empty road.

Ok, that doesn't change the fact that for two objects to collide with each other, you need space, but you don't need time. You need space, but you use the concepts of height, length and width to measure them.

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No one says that these things a perfect. Or even that they reflect the underlying reality (if that even means anything). They are scientific models and theories. In these models, space and time are dimensions that can be used to measure the location of events.

It seems that a lot of people object to relativity (or quantum theory, or whatever) because it is not some metaphycal explanation of "reality". No. It isn't intended to be. That is not what science is for. As someone else said, "You want Philosophy. Second door on the left."

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Strange has 'hit the nail on the head' here. You have to remember that in theoretical physics one is looking for mathematical models of nature. You look at nature and realise that space (length and position) and time (or duration) are useful ideas. So you develop a mathematical understanding of these concepts and this may well feed back into your more intuitive notions based on your observations. And this 'feedback loop' goes on. All notions in physics are inherently mathematical and 'man-made'. The point is they should be useful in describing our Universe. The question of 'reality', 'existence' etc. is not really at the forefront. Pragmatically, one usually accepts that the only 'real' things are what you can measure and thus physics is full of 'non-real' concepts.

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Strange has 'hit the nail on the head' here. You have to remember that in theoretical physics one is looking for mathematical models of nature. You look at nature and realise that space (length and position) and time (or duration) are useful ideas. So you develop a mathematical understanding of these concepts and this may well feed back into your more intuitive notions based on your observations. And this 'feedback loop' goes on. All notions in physics are inherently mathematical and 'man-made'. The point is they should be useful in describing our Universe. The question of 'reality', 'existence' etc. is not really at the forefront. Pragmatically, one usually accepts that the only 'real' things are what you can measure and thus physics is full of 'non-real' concepts.

Yes, but I agree with you on this. I just don't agree with confusing the verb need with the verb use.

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Yes, but I agree with you on this. I just don't agree with confusing the verb need with the verb use.

If you want to collect the one million pounds I offered, you need to be at the right place and at the right time - which I am not telling you because you don't need it.

Anyway, this is a strawman argument as the word "need" does not form part of the theory of relativity. If you don't want to use the word, you don't need to. (See what I did there)

Edited by Strange
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If you want to collect the one million pounds I offered, you need to be at the right place and at the right time - which I am not telling you because you don't need it.

Anyway, this is a strawman argument as the word "need" does not form part of the theory of relativity. If you don't want to use the word, you don't need to. (See what I did there)

Well, I don't need it, but for 1 million pounds I can use it

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Yes, but I agree with you on this. I just don't agree with confusing the verb need with the verb use.

Within Einsteinian one needs to use time as it is inherently written into the formalism.

For dynamical problems how can we get away with not using time?

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Within Einsteinian one needs to use time as it is inherently written into the formalism.

For dynamical problems how can we get away with not using time?

As a measuring tool? We can't get away from using time and clocks. But take my answers always with a pinch of salt, I am not the expert here, I just try my luck when I write...

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