# Time comparison

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Oh dear lord, what happened in here?

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YT, you're completely misunderstanding what a 'frame of reference' is in the context of relativity. Read this!

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

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I don't understand what you're confused about YT...

From my point of view when you shoot my melon.

Cause - your itchy trigger finger.

Effects -

I see a flash from your gun, then my melon exploding along with a splosh sound, then the sound of the gun shot.

From your point of view you see the flash and hear the bang then see my melon exploding (and a splosh, if you've got good hearing).

I know that's rudimentary but what's there to cock up??

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MS, Ill see it and experience it differently to you, me behind the gun and you or whomever holding the melon.

if the trigger gets pulled at at 11:20:30 exactly, and the melon pops at 11:20:31 it still doesnt change the time WHEN I pulled the trigger.

thats a constant, it was at 11:20:30

no matter when or how YOU experience it.

its all subjective

you see the flash, the melon splosh then CRACK, I see flash hear crack then the melon evaporates, I may hear that sound bounce back too.

the fact is light or sound, both are finite in speed, but that shouldnt detract from NOW

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MS' date=' Ill see it and experience it differently to you, me behind the gun and you or whomever holding the melon.

if the trigger gets pulled at at 11:20:30 exactly, and the melon pops at 11:20:31 it still doesnt change the time WHEN I pulled the trigger.

thats a constant, it was at 11:20:30

no matter when or how YOU experience it.

its all subjective

you see the flash, the melon splosh then CRACK, I see flash hear crack then the melon evaporates, I may hear that sound bounce back too.

the fact is light or sound, both are finite in speed, but that shouldnt detract from NOW[/quote']

It doesn't detract from NOW.

If the sun blew up 8 minutes ago and we just start to see the effects right now it might as well have just blown up right now.

That wouldn't be the case if you were on a ship orbitting the sun at half the distance we are because they'd have blown up 4 minutes ago. So from their point of view (or relative to them compared to us) now was 4 minutes ago.

But with you yourself not being on that ship it's irrelevant.

The sun blowing up and it taking 8 minutes for us to feel the effects so it might as well have blown up right now, is about the simplest scenario I can come up with so if you can explain the confusion in that it might help.

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if the trigger gets pulled at at 11:20:30 exactly' date=' and the melon pops at 11:20:31 it still doesnt change the time WHEN I pulled the trigger.[/quote']

In America, you pulled the trigger at 6:20:30 exactly!

Time is NOT absolute. Time measurements are just a human invention, and the rate of the flow of time has been proven to be non-uniform.

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the confusion PROBABLY arrises from the definition of "Now"

I see it as an Absolute, Now just IS.

I clap my hands and the whole universe stops in its tracks, maybe a star just goin Super Noava or 2 asteroids colliding etc...

THAT is the NOW I speak of, freeze everything and have a look around at these items, maybe a million light years away, doing what they were doing, THAT is NOW.

no matter how long it takes for the sound or the light to hit your eyes or ears (thats only a speed limitation) its certainly not the "NOW"

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the confusion PROBABLY arrises from the definition of "Now"

I see it as an Absolute' date=' Now just IS.

[/quote']

In reality, though, now is only now for you. It is not an absolute.

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there MUST be an absolute though?

an event occurs at NOW, that NOW is everywhere, whether the effects are seen or not in their ref frame.

"I never saw the Bus coming at me, so Im NOT DEAD"

its denial based on light speed, "the photons didnt hit my eyes until just, so before that, it Didnt happen"?????

WTF?

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Absolute time...

I think that's the way gravity equations works. You compute the position of the sun in the sky where he is now . If you want to observe it with your telescope, you will point to where it was 8 minute ago.

There is also an other way to think about now: Now is the sensation caused by the set of perception that hit my senses. Everybody have is own Now.

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Ive a feeling that the concept of Absote time doesnt exit in Physics tho, Im sure someone would have picked up on what I mean if it did exist, so Im left wondering if its a mental problem I have in Understanding it?

Ide accept that if it could be shown conclusively one way or the other.

as for now, Im hanging mid air, not certain of either, Ide accept being wrong if shown in a way I can understand and beleive, until then Im certain there must be such a thing as Abosute "NOW".

thats nothing though, I recon theres an absolute motion also! within the frame of Big Bang center point, and staying still in reference to that position.

but indeed thats material for a different thread again

step at a time, I wanna get my head around this one 1st )

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there MUST be an absolute though?

an event occurs at NOW' date=' that NOW is everywhere, whether the effects are seen or not in their ref frame.[/quote']

Fraid not. Time is not absolute.

I know what you mean by 'absolute time'; a form of universal clock, where you can say 'This happened THEN!', and then ream off a number of things which happened simultaneously.

This is how Newton saw time; it is not how it exists under Einsteinian physics, and, as evidence has shown, the universe.

For example, we perceive particles we create to live longer the faster their going, due to time dilation. From their point of view, they take the same time to decay, but ours has them going so fast there's a noticable difference.

All these effects (mass gaining, time slowing, lengths contracting) take place in this ratio, where v is the object's velocity relative to the rest frame, and c is the speed of light.

SQRT ( 1 - (v^2/c^2)).

[edit2]

There's not absolute motion either. That went out with Newton, and is also precluded by Einstein.

If there's an absolute background, special relativity doesn't work, because you lose the equivalence of all the rest frames.

And special relativity does work.

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I think that's the way gravity equations works. You compute the position of the sun in the sky where he is now . If you want to observe it with your telescope, you will point to where it was 8 minute ago.

Am I right about how orbits are calculated using Newton equations? The positions calculated are positions in the absolute NOW of YT ???

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Absolute time...

I think that's the way gravity equations works. You compute the position of the sun in the sky where he is now . If you want to observe it with your telescope' date=' you will point to where it was 8 minute ago.[/quote']

That's only under newtonian physics; under General Relativity, gravity waves take time to travel, just the same as light (and at the same speed too). If the sun was destroyed 7 minutes ago, there is no way to know for another 60 seconds, because any ways we have of knowing that it's been destroyed all take 8 minutes to get to us.

Or, to put it another way, the speed of light is the universal speed limit for information transfer, which includes force interactions.

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I know that people here thinks Tom Flander is a crackpot, but I read some articles of what he call "gravity aberation" The delay in the gravitation propagation would cause orbit degradation...(http://www.metaresearch.org/cosmology/speed_of_gravity.asp).

That make sense to me. Maybe I missed the flaw in his reasonning??? What do you think of that ?

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the confusion PROBABLY arrises from the definition of "Now"

I see it as an Absolute' date=' Now just IS.

I clap my hands and the whole universe stops in its tracks, maybe a star just goin Super Noava or 2 asteroids colliding etc...

THAT is the NOW I speak of, freeze everything and have a look around at these items, maybe a million light years away, doing what they were doing, THAT is NOW.

no matter how long it takes for the sound or the light to hit your eyes or ears (thats only a speed limitation) its certainly not the "NOW" [/quote']

I don't see anything wrong with any of that. Time for some magic.

If you could magically step outside the universe and clapped your magic hands that could freeze the entire universe in its tracks right now (at this whatever moment of time you're in right now), then look around inside it with a magic crystal ball you would see the entire universe frozen in the state of now. Earth would be here, Mars would be over there, the sun would be over there, etc..

Let's say I stood on the Sun with a ball and you stayed here with a ball. We used a magic radio (no 8 minute waiting time for signal travelling) one of us counted down to 0 then shouted "Now!" as a signal for us to both throw our balls into the air at the same moment in time, we would. So that's the conventional now we all use.

But if you then went and looked through a telescope you'd have to wait 8 minutes to see me throwing my ball into the air even though that happened 8 minutes ago. So if the Sun blew up 8 minutes ago and we're only just feeling the effects right now then it might as well have just blown up right now.

Whatever happened on the Sun 8 minutes ago is irrelevent until we can see or feel its effects here on Earth now.

The way I see it there are two nows, the conventional now and the now relative to you.

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I know that people here thinks Tom Flander is a crackpot' date=' but I read some articles of what he call "gravity aberation" The delay in the gravitation propagation would cause orbit degradation...(http://www.metaresearch.org/cosmology/speed_of_gravity.asp).

That make sense to me. Maybe I missed the flaw in his reasonning??? What do you think of that ?[/quote']

van Flandern is a crackpot, but he also has a degree in either physics or astronomy. Not all of what he spouts is garbage, it's just that he embraces alot of non-mainstream views. It may very well be that his conclusions are correct while the explanation is all wrong. Or maybe just subtly wrong. It isn't always easy to spot the transition from mainstream to crackpottery.

As for his contention, I can't really evaluate it. I do notice he states that an eclipse doesn't have the light and gravity forces line up, but I didn't see where he explained how he measured the gravity vector.

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I don't see anything wrong with any of that.

Except it is incorrect. You forgot that part.

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I think the reason YT is having problems understanding your explanations is that you are explaining it in terms of "no absolute universal time" whereas he is seeing it from the complementary position; that of universally fixed simultaneity of event points.

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Except it is incorrect. You forgot that part.

So if you froze time for the entire universe NOW so everything stopped and went to visit everywhere/thing the position and states of those things will have changed, even though time for the entire universe was frozen??

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So if you froze time for the entire universe NOW so everything stopped and went to visit everywhere/thing the position and states of those things will have changed, even though time for the entire universe was frozen??

You can't stop time, so basing thought experiments around it is rather stupid.

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You can't[/i'] stop time, so basing thought experiments around it is rather stupid.

Nicely phrased...

Since you're incapable of explaining something to me with that scenario, I'll do something clever and rephrase it then.

At this very moment in time, right now (as I type this) you're where you are, I'm where I am, Mars is where it is, etc...

It might not be relevent to where everything else is and that now is my now and not your now because when you read this everything will have moved but everything was still at the position and in the same state for everyone. You were still where you where and I was still where I was.

What?

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At this very moment in time' date=' right now (as I type this) you're where you are, I'm where I am, Mars is where it is, etc...

It might not be relevent to where everything else is and that now is my now and not your now because when you read this everything will have moved but everything was still at the position and in the same state for everyone. You were still where you where and I was still where I was.[/quote']

An observer moving relative to you will not agree that Mars is where you say it is. Things are not in the same state for everyone. Only in your reference frame.

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What?

Where, how and why?

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