# I have difficulties understanding relativity

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Guys you know what they say. Time is effected by the gravitial pull and speed. Here is my question. How can they be sure that the effected thing is time but not the watch, the clock itself?

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Partly because that is what the theory says - and the theory is confirmed by evidence.

But also, how could you changing your own speed affect other people’s clocks?

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Guys you know what they say. Time is effected by the gravitial pull and speed. Here is my question. How can they be sure that the effected thing is time but not the watch, the clock itself?

It's not really about the clock. It doesn't matter if the clock is a wind-up wristwatch, a battery operated quartz crystal controlled digital watch, a sand-filled egg timer, the beating of someone's heart, or the regular drip of water out of a small hole. It doesn't matter how the clock works, as long as the clock measures time, and time is affected, the clock is affected (from the point of view of some observer moving relative to that clock, or at some other gravitational potential).

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oh that is very informative, thank you.

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Guys you know what they say. Time is effected by the gravitial pull and speed. Here is my question. How can they be sure that the effected thing is time but not the watch, the clock itself?

I think it might be easier to understand if you consider that;

Spacetime is inseperable, our 3 spacial dimentions are always glued together with our 1 temporal dimention. Gravity or velocity (its not only gravity which affects clocks) cause both time dilation and lenght contraction...apart from clocks running slower for a moving or gravity affectet frame also things change their size within our 3 spacial dimentions. It is not the clocks which run slower, it is time itself - clocks just measure the effect.

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20 minutes ago, koti said:

Spacetime is inseperable, our 3 spacial dimentions are always glued together with our 1 temporal dimention.

A good way to put it. +1

# I have difficulties understanding relativity

The way to understabding is to do it in stages, just like modern relativity was developed in stages.

To start here is an experiment you can perform for yourself.

I have located a point P1 at (X1 , Y1) on an XY plot as shown by the dotted lines to the axes X and Y.

Then I have drawn some rotated axes X' and Y'  (the dashed axis lines) and again located the coordinates of P1 , now with different values X1' and Y1'.

This is shown by the dash-dot chain lines.

For the experiment introduce a second point P2 with its own coordinates, as shown.

Now either (or better both) measure or calculate the distance between P1 and P2 in both the XY and the X'Y' coordinates.

You should be able to convince yourself they are the same.

For reference the formulae are

${d_{XY}} = \sqrt {{{\left( {{X_2} - {X_1}} \right)}^2} + {{\left( {{Y_2} - {Y_1}} \right)}^2}}$

and

${d_{X'Y'}} = \sqrt {{{\left( {{X_2}' - {X_1}'} \right)}^2} + {{\left( {{Y_2}' - {Y_1}'} \right)}^2}}$

The coordinates themselves measure position, of a single point.

You need two points to define (measure) a distance.

Both position and distance are properties.
Much of modern Physics involves the search for properties that are the same in different coordinate systems.

Such properties are called invariants.

If you are still interested, we can apply this to time in another post.

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i studied law and a bit of an artist myself but terrible at understanding these kind of intellectuality. Thank you for your efford, tho.

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i studied law and a bit of an artist myself but terrible at understanding these kind of intellectuality. Thank you for your efford, tho.

One of the moderators here is/ was a top notch lawyer.

And a very keen mind to boot.

But if you don't want to put in the effort I'm sorry but you will have to take things on trust, rather than understand them.

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Guys you know what they say. Time is effected by the gravitational pull and speed. Here is my question. How can they be sure that the effected thing is time but not the watch, the clock itself?

This intrigued me too, but as well as the other posts above, i found this link very helpful:  http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html

P.S. I hope you don't mind that i changed your " gravitial " to  " gravitational ".

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5 hours ago, pzkpfw said:

It's not really about the clock. It doesn't matter if the clock is a wind-up wristwatch, a battery operated quartz crystal controlled digital watch, a sand-filled egg timer, the beating of someone's heart, or the regular drip of water out of a small hole. It doesn't matter how the clock works, as long as the clock measures time, and time is affected, the clock is affected (from the point of view of some observer moving relative to that clock, or at some other gravitational potential).

And this has been tested with various kinds of atomic clocks, and using different elements. Time is affected the same way regardless of the kind of clock that was used.

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• 2 weeks later...
On ‎2‎/‎10‎/‎2018 at 5:04 AM, studiot said:

One of the moderators here is/ was a top notch lawyer.

And a very keen mind to boot.

You say that as if they don't normally go together!

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21 hours ago, HallsofIvy said:

You say that as if they don't normally go together!

It's always the 90 percent of Lawyers that give the rest a bad rep... (I kid of course...please don't sue me)

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• 2 weeks later...

It seems cogent enough for me to mention that my comprehension of relativity isn't necessarily very in-depth. However, a rudimentary understanding of it can be summarized by the following: The relativity theories are basically about converting matter into energy and vice versa. The proverbial E=mc^2 equation, in a sentence, would be something along the lines of: "Energy equals mass times the speed of light squared", with the "c" representing the constant of the speed of light (186,000 miles per second or 300,000 kilometers per second). I'm not entirely sure of how to make a distinction between the special and general relativity theories, apart from knowing that Einstein published papers on them ten years apart (if memory serves me correctly, the former was in 1905 and the latter in 1915). Additionally, I think relativity posits that time is relative, and that theoretically if a spacefaring vessel were traveling at light speed and was further accelerated, its mass would become infinite.

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18 minutes ago, The 321 Anomaly said:

I'm not entirely sure of how to make a distinction between the special and general relativity theories, apart from knowing that Einstein published papers on them ten years apart

As an amateur I'm open to correction, but the way I see it, is that SR is simply a "subset" or special case of GR, and neglects gravitational effects.

Also the fact that the speed of light is a finite constant, leads to the conclusion that it is space and time that is variable and that there is no universal applicable now.

Quote

Additionally, I think relativity posits that time is relative, and that theoretically if a spacefaring vessel were traveling at light speed and was further accelerated, its mass would become infinite.

Yes, time and space are relative as mentioned previously, and as a body approaches "c" its relativistic mass increases approaching infinity, and hence why reaching "c" is impossible.

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38 minutes ago, The 321 Anomaly said:

The relativity theories are basically about converting matter into energy and vice versa.

I would say that special relativity is more about the relationship between time and space, as seen by different observers in relative motion. The equivalence of mass and energy can be derived as a consequence of relativity (and Maxwell's equations).

General relativity adds to this the effects of mass and energy causing gravity.

16 minutes ago, beecee said:

Also the fact that the speed of light is a finite constant

Not just constant but, more importantly, invariant: i.e. the same for all observers.

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16 minutes ago, Strange said:

Not just constant but, more importantly, invariant: i.e. the same for all observers.

Bingo!

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I have a quick question:

Time is relative. So in certain circumstances time acts different and we are able to measure how different it behaves.

Here is my question: Is there a test done with an uranium-like material.

So, radiactive materials age very fast. It should age differently in given circumstances and we should be able to masure how different it ages.

Does anyone knows such a test? Can you share with me?

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I have a quick question:

Time is relative. So in certain circumstances time acts different and we are able to measure how different it behaves.

Here is my question: Is there a test done with an uranium-like material.

So, radiactive materials age very fast. It should age differently in given circumstances and we should be able to masure how different it ages.

Does anyone knows such a test? Can you share with me?

I don't want to be rude, but have you read this thread?

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So, radiactive materials age very fast. It should age differently in given circumstances and we should be able to masure how different it ages.

Does anyone knows such a test? Can you share with me?

It has certainly been seen with muons: http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html

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2 hours ago, dimreepr said:

I don't want to be rude, but have you read this thread?

Oh, what made you think that?

2 hours ago, Strange said:

It has certainly been seen with muons: http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html

Thank you!

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