Something I don't understand about astronomy and distance to objects.
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14-04-2013, 08:55 AM
RE: Something I don't understand about astronomy and distance to objects.
(14-04-2013 12:36 AM)Heywood Jahblome Wrote:  When both clocks were stationary in spacetime, all their momentum is expending moving thru just the time dimension. This is true even if the clocks are being carried away from each other by expanding spacetime. However if one clock is set in motion thru spacetime, then some of its motion thru spacetime is taken away from traveling thru the time dimension and instead is used to travel thru spatial dimension. That's why clocks in motion slow down.

Maybe I am wrong but I read Ghost's comments as a claim that the expansion of spacetime was responsible for destroying an absolute now. I don't think that is correct. There is no absolute universal now, but not because spacetime expands. I would re-read my copy of The Fabric of the Cosmos to see exactly what Greene says about it, but I gave it away.

So utterly fucked up.
1. Stationary objects have no momentum.
http://en.wikipedia.org/wiki/Momentum
2. The clock slows ONLY "relative" to the stationary observer, NOT for the clock in motion. THERE IS NO ABSOLUTE NOW.
3. It IS correct. It is the one of THE fundamental discoveries of Relativity. Why TF do you THINK it's called "relativity" ?

Oh right.
1. "Oh it's Spring". 2. "Oh I gave my book away". 3. "Oh the dog ate my homework".

That's right.
Dawkins got it wrong.
And BlowJob got it right.
He's special.
Very very special.
So very very special.
He sees things noone else has understood.
So very special.

We need a new thread about "special".

Weeping

Insufferable know-it-all.Einstein
Those who were seen dancing were thought to be insane by those who could not hear the music - Friedrich Nietzsche
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14-04-2013, 09:37 AM
RE: Something I don't understand about astronomy and distance to objects.
Hey, Wood.

Don't sweat the assholes of the world Cool

Greene talks about it in the above video I posted.

I think cjlr and Chas may have a fuller grasp of it than I, but at the most basic level, in our now, we're watching, in real time, something that happened ten billion years ago, the same way you observe yourself brushing your teeth in the mirror. For example, no human being has ever seen the Sun. The Sun is about 4 light minutes away. So that big ball of fire we take for granted has always been four minutes ago. But it occupies our now. Then when you throw movement into all of this, you wind up with time dilation, which has been proven through experiment.

I think what I can say about your clocks is that if they were a million light years apart, and I was sitting beside one of them, the other would be a million years too slow. I think that where you may be correct though is that in order for time dilation to occur, there needs to be movement either towards or away.

One thing Greene said was clear. There is no now. All of time occurs SIMULTANEOUSLY. That's a mind-fuck, but if it's true, it's true.

But yeah, to address your concern directly, I'm not saying the expansion of space-time annihilates now, it's the nature of space-time that does it. There never was a now. Assuming there was a now was a mistake on our part.

For those of us who believe in physics, this separation between past, present, and future is only an illusion, however tenacious.
-Albert Einstein

Peace and Love and Empathy,

Matt
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14-04-2013, 10:37 AM (This post was last modified: 14-04-2013 10:49 AM by Heywood Jahblome.)
RE: Something I don't understand about astronomy and distance to objects.
(14-04-2013 08:55 AM)Bucky Ball Wrote:  
(14-04-2013 12:36 AM)Heywood Jahblome Wrote:  When both clocks were stationary in spacetime, all their momentum is expending moving thru just the time dimension. This is true even if the clocks are being carried away from each other by expanding spacetime. However if one clock is set in motion thru spacetime, then some of its motion thru spacetime is taken away from traveling thru the time dimension and instead is used to travel thru spatial dimension. That's why clocks in motion slow down.

Maybe I am wrong but I read Ghost's comments as a claim that the expansion of spacetime was responsible for destroying an absolute now. I don't think that is correct. There is no absolute universal now, but not because spacetime expands. I would re-read my copy of The Fabric of the Cosmos to see exactly what Greene says about it, but I gave it away.

So utterly fucked up.
1. Stationary objects have no momentum.
http://en.wikipedia.org/wiki/Momentum
2. The clock slows ONLY "relative" to the stationary observer, NOT for the clock in motion. THERE IS NO ABSOLUTE NOW.
3. It IS correct. It is the one of THE fundamental discoveries of Relativity. Why TF do you THINK it's called "relativity" ?

Oh right.
1. "Oh it's Spring". 2. "Oh I gave my book away". 3. "Oh the dog ate my homework".

That's right.
Dawkins got it wrong.
And BlowJob got it right.
He's special.
Very very special.
So very very special.
He sees things noone else has understood.
So very special.

We need a new thread about "special".

Weeping

A stationary object in Minkowski space would be frozen in time and not just in the spatial dimensions. In the examples the clocks always have momentum because they never stop moving thru the time dimension.

I never claimed there was an absolute now.
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14-04-2013, 10:44 AM
RE: Something I don't understand about astronomy and distance to objects.
(14-04-2013 09:37 AM)Ghost Wrote:  Hey, Wood.

Don't sweat the assholes of the world Cool

Greene talks about it in the above video I posted.

I think cjlr and Chas may have a fuller grasp of it than I, but at the most basic level, in our now, we're watching, in real time, something that happened ten billion years ago, the same way you observe yourself brushing your teeth in the mirror. For example, no human being has ever seen the Sun. The Sun is about 4 light minutes away. So that big ball of fire we take for granted has always been four minutes ago. But it occupies our now. Then when you throw movement into all of this, you wind up with time dilation, which has been proven through experiment.

I think what I can say about your clocks is that if they were a million light years apart, and I was sitting beside one of them, the other would be a million years too slow. I think that where you may be correct though is that in order for time dilation to occur, there needs to be movement either towards or away.

One thing Greene said was clear. There is no now. All of time occurs SIMULTANEOUSLY. That's a mind-fuck, but if it's true, it's true.

But yeah, to address your concern directly, I'm not saying the expansion of space-time annihilates now, it's the nature of space-time that does it. There never was a now. Assuming there was a now was a mistake on our part.

For those of us who believe in physics, this separation between past, present, and future is only an illusion, however tenacious.
-Albert Einstein

Peace and Love and Empathy,

Matt

Google "block theory of time" or "eternalism".......which if true....means Bucky is an eternal being.
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14-04-2013, 12:29 PM
RE: Something I don't understand about astronomy and distance to objects.
(14-04-2013 12:36 AM)Heywood Jahblome Wrote:  If space expanded so that the clocks were one light minute apart, an observer at one clock would see the other clock as being 1 minute behind because it would take one minute for the information transmitted from one clock to reach the other. However both clocks would still share the same "now". Suppose you are exactly between the two clocks. If observers at each clock were instructed to send a light pulse to you when they observe a specific time on their clocks, you would receive both light pulses at the same time. The reason for this is because the speed of light is constant and the clocks remain synchronized.

Well, let's consider the two, after space has stopped expanding (it's a toy problem, let's just roll with it). Observer 1 has seen clock 2 begin beside him, with its pulses essentially simultaneous with his own. He or she has observed it move away, during which the pulses were slightly less frequent. Then it stopped, and the pulses are again one per minute. From this he or she may conclude that clock 2 has stopped its (relative) motion to him/her. It is true, in a sense, that they (again) share a 'now'. But it's also meaningless, since they can't act on it unless they communicate, and any communication is bound by the speed of light - so they won't perceive each other, or indeed any other event, as being simultaneous anymore. This is true whether they both remain beside each other, whether one accelerates away and then to a stop, or whether both do. The return to a shared reference frame means their pulses have the same frequency again, but that's all it means.

Quote:Now let's change the scenario just a little bit. The clocks start out exactly synchronized as before. Suppose space isn't expanding at all but instead one clock is set in motion thru space and travels a distance of one light minute. You happen to be stationed exactly between the two. If the observers at each clock send their light pulses at the designated time, you will observe them arriving at your location not at the same time as in the first scenario, but a different times. The reason for this is because the clocks are no longer synchronized.

No. In the above case they only remain 'synchronized' for an observer to whom they are moving symmetrically. They cannot be said to be synchronized in any meaningful way even so, because their knowledge is limited to what they can pass back and forth (at lightspeed, max).

The situations are identical! If clock 1 accelerates away, then stops one light-minute away, the light pulses received by 'stationary' observer 2 will appear exactly the same as if space had expanded between them at the same rate. Or if observer 1 had jetted off and left clock 2 hind. Or if they both moved away from each other (at, to overly-simplify it, half the acceleration).

(14-04-2013 09:37 AM)Ghost Wrote:  I think cjlr and Chas may have a fuller grasp of it than I, but at the most basic level, in our now, we're watching, in real time, something that happened ten billion years ago, the same way you observe yourself brushing your teeth in the mirror. For example, no human being has ever seen the Sun. The Sun is about 4 light minutes away. So that big ball of fire we take for granted has always been four minutes ago. But it occupies our now. Then when you throw movement into all of this, you wind up with time dilation, which has been proven through experiment.

I think what I can say about your clocks is that if they were a million light years apart, and I was sitting beside one of them, the other would be a million years too slow. I think that where you may be correct though is that in order for time dilation to occur, there needs to be movement either towards or away.

One thing Greene said was clear. There is no now. All of time occurs SIMULTANEOUSLY. That's a mind-fuck, but if it's true, it's true.

It's true that the only possible way to define 'now' is in terms of what you can observe at any given moment. Though the sun's actually about 8-odd light minutes away!

Time dilation (and its more obscure twin brother, length contraction) does occur due to relative movement, but that's complicated by the occurrence of acceleration, and the presence of gravity wells (kind of the same thing, really), which is what special relativity describes.

'Now' is one of those ideas that makes enough sense in day to day life, and has been around since forever, that we still roll with it now (as it were). Like numbers. Not actually real - but pretty damn useful.

Quote:There never was a now. Assuming there was a now was a mistake on our part.


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14-04-2013, 04:07 PM
RE: Something I don't understand about astronomy and distance to objects.
(14-04-2013 09:37 AM)Ghost Wrote:  Hey, Wood.

Don't sweat the assholes of the world Cool

Greene talks about it in the above video I posted.

I think cjlr and Chas may have a fuller grasp of it than I, but at the most basic level, in our now, we're watching, in real time, something that happened ten billion years ago, the same way you observe yourself brushing your teeth in the mirror. For example, no human being has ever seen the Sun. The Sun is about 4 light minutes away. So that big ball of fire we take for granted has always been four minutes ago. But it occupies our now. Then when you throw movement into all of this, you wind up with time dilation, which has been proven through experiment.

I think what I can say about your clocks is that if they were a million light years apart, and I was sitting beside one of them, the other would be a million years too slow. I think that where you may be correct though is that in order for time dilation to occur, there needs to be movement either towards or away.

One thing Greene said was clear. There is no now. All of time occurs SIMULTANEOUSLY. That's a mind-fuck, but if it's true, it's true.

But yeah, to address your concern directly, I'm not saying the expansion of space-time annihilates now, it's the nature of space-time that does it. There never was a now. Assuming there was a now was a mistake on our part.

For those of us who believe in physics, this separation between past, present, and future is only an illusion, however tenacious.
-Albert Einstein

Peace and Love and Empathy,

Matt


Eight minutes, but who's counting? Drinking Beverage

Skepticism is not a position; it is an approach to claims.
Science is not a subject, but a method.
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14-04-2013, 07:13 PM
RE: Something I don't understand about astronomy and distance to objects.
Hey, cjlr.

Thanks for bringing the knowledge.

As a investigator of ideology, the mind and socially constructed reality, I can 100% understand and get behind the idea that important concepts just seem real because we're used to them.

All models are wrong, but some are useful.
-George EP Box

Peace and Love and Empathy,

Matt
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