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Author Topic:   What is "the fabric" of space-time?
IamJoseph
Member (Idle past 2904 days)
Posts: 2822
Joined: 06-30-2007


Message 271 of 327 (473441)
06-29-2008 8:23 AM
Reply to: Message 261 by john6zx
06-29-2008 2:23 AM


Re: Fabric of Space-Time
quote:
Is energy a physical thing or not? Yes/No?

All universe content is physical [as opposed to what?!], including percieved nothingness or what we cannot yet see. Everything is basically from the same source, thus the quest to find the smallest denominator particle and a unifying force.

Energy is an effect of drag and density levels, and not a seperate, non-universal product. If the question was, what is behind all physicality, even behind quark realms, I would say a program, and one which is responsible for all results. Its not the fire or a bullet from a gun which is the end point; ultimately it is a program which produced the gun, the bullet and the fire. Physicality is a lumping or denser formation of the same particles which make up energy and all other stuff.

quote:

What is a sublimity?


This is an extra-ordinary leaping, and can apply however it is contexted.

Edited by IamJoseph, : No reason given.


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Son Goku
Member
Posts: 1207
From: Ireland
Joined: 07-16-2005
Member Rating: 5.2


Message 272 of 327 (473448)
06-29-2008 10:25 AM
Reply to: Message 267 by john6zx
06-29-2008 3:34 AM


Re: the gravity of general relativity
O.K. So what are physical things made of?

Who knows? Depends on what you want. I could give an answer about particles being Poincaré irreps, e.t.c. However that's tangential to the thread.

Matter is the condensation of energy. The more energy condenses, the less space it occupies and the more solid it becomes. Energy becomes matter if condensed. Matter becomes energy if dispersed.

That is incorrect. You cannot "condense" energy and make it become matter. Show me a process where you take some "ability to do work" and condense it to make matter. If matter was only made of energy where would electric charge come from? In no theory in physics is matter made of energy.

Matter becomes energy if dispersed.

Again, there is no process where extremely disperse matter becomes energy. Name one, if you don't think this is the case.

Energy=mass times the speed of light squared.

Which expresses how much energy a given amount of mass (the resistence to motion) is equivalent to. Not that matter is made of energy.

You can not consider matter without also considering energy.

True, but the same could be said of electric charge, color charge, momentum, spin, e.t.c. It doesn't mean matter is made of energy.

Tell me what you think matter is made of.

There are several answers one could give, which may or may not be satisfactory. That doesn't change the fact that matter isn't made of energy.

This message is a reply to:
 Message 267 by john6zx, posted 06-29-2008 3:34 AM john6zx has replied

Replies to this message:
 Message 274 by cavediver, posted 06-29-2008 1:13 PM Son Goku has replied
 Message 310 by john6zx, posted 07-13-2008 6:05 AM Son Goku has replied

  
AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 273 of 327 (473451)
06-29-2008 11:15 AM
Reply to: Message 271 by IamJoseph
06-29-2008 8:23 AM


IaJ set to a post an hour
Since we don't need any more nonsense posing as English than we already have I'm slowing you down for now. Suspension will follow.

Edited by AdminNosy, : No reason given.


This message is a reply to:
 Message 271 by IamJoseph, posted 06-29-2008 8:23 AM IamJoseph has taken no action

  
cavediver
Member (Idle past 2879 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 274 of 327 (473457)
06-29-2008 1:13 PM
Reply to: Message 272 by Son Goku
06-29-2008 10:25 AM


It's a sad day...
What with this reply SG just submitted, and his recent reply to randman, it seems that SG's keen resolve and determined patience are starting to show the very first signs of cracks. Reminds me of someone else, much further along the road to complete dispair ;)

Edited by cavediver, : No reason given.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 272 by Son Goku, posted 06-29-2008 10:25 AM Son Goku has replied

Replies to this message:
 Message 275 by rueh, posted 06-29-2008 3:48 PM cavediver has replied
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rueh
Member (Idle past 2897 days)
Posts: 382
From: universal city tx
Joined: 03-03-2008


Message 275 of 327 (473462)
06-29-2008 3:48 PM
Reply to: Message 274 by cavediver
06-29-2008 1:13 PM


?????
There was a point brought up earlier in this thread that I am still confused about. Cave diver I would appreciate any help you can give me in raping my mind around this. Mainly that as we look farther out into space we are seeing light cones from more and more distant objects. These objects all have a more distinct red shift than closer light cones. Now the explanation I have heard is that these objects, having more space in between them move farther and faster relative to us. Being that space has a repulsive force in the manner of dark energy. All this makes sense except for the part that we are seeing light cones that are from an earlier time in the age of the universe. So wouldn't we have an older universe moving faster than today? Ex: older more distant objects move very fast away, newer, closer objects moving not so fast. Is this due to the effect of space itself stretching the frequency emitted from the objects? Any help would be appreciated thanks.

This message is a reply to:
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cavediver
Member (Idle past 2879 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 276 of 327 (473472)
06-29-2008 6:52 PM
Reply to: Message 275 by rueh
06-29-2008 3:48 PM


Re: ?????
I would appreciate any help you can give me in raping my mind...

:eek: think that should be *wrapping* ;)

Ex: older more distant objects move very fast away, newer, closer objects moving not so fast. Is this due to the effect of space itself stretching the frequency emitted from the objects?

Yes, this is definitely one way to think of it. It is not that we are seeing the distant galaxies and quasars moving away at velocities that they were moving away from us at that time, which would be the case if this were simply a Doppler effect. The Universe has been expanding as the photons have been travelling towards us through the billions of years, and this expansion is the reason for the red-shift.

There is actually a far far simpler explanation, which I may as well mention as you brought up "light-cones", despite it requiring more insight into space-time physics. As you may know, photons actually have no "length", as the proper distance between the emission and absorption of a photon is zero (think of infinite length contraction), and there is no time between emission and absorption (think of infinite time dilation.) So how does the red-shift arise in this context? It is simply a result of the light-cone at emission pointing in a different direction to the light cone at absorption. The photon allows us to overlap the light cones (despite being separated in our minds by billions of years and billions of light-years) and take a measurement of the difference between them.

Edited by cavediver, : No reason given.


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onifre
Member (Idle past 2187 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 277 of 327 (473515)
06-30-2008 11:40 AM
Reply to: Message 275 by rueh
06-29-2008 3:48 PM


Re: ?????
raping my mind

That only happens if you become Republican :)


All great truths begin as blasphemies

I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth.


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rueh
Member (Idle past 2897 days)
Posts: 382
From: universal city tx
Joined: 03-03-2008


Message 278 of 327 (473516)
06-30-2008 11:44 AM
Reply to: Message 277 by onifre
06-30-2008 11:40 AM


Re: ?????
Actualy I like to make up lymerics to help me remember, so raping kinda fits :laugh: that and my spelling is terrible.

Thank you for the explenation, that makes more sense. I tried to think of it the same way a laser gyroscope works just over much larger scales.


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onifre
Member (Idle past 2187 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 279 of 327 (473518)
06-30-2008 11:59 AM
Reply to: Message 269 by john6zx
06-29-2008 6:55 AM


Re: the gravity of general relativity
You say it exists. I say, exists in what way. What makes it what it is? Break it down if you have to. Example: Spacetime is made of space and time, and then go on to show how space is a thing that exist as some sort of energy. Then go on and show how time exists as some sort of energy. Or something like that. I am sure that you get the idea.

The problem is that you are not understanding the explanations given to you by people who have been involved in cosmology for years, your understanding of the subject is then limited to your layman interpretations and definitions. What is being explained therefore passes you by. You repeateing your questions just further shows that you are unwilling to learn properly.

I'll ask you the simple question of : Can spacetime be warped?

You don't even need to search, heres the answer used for highschool physics classes,

http://www.pbs.org/deepspace/classroom/activity5.html

If you get the answer to that, and by 'get' I mean fully comprehend, you may also get a better understanding of what is meant by 'physical' in relation to spacetime...hope that helped.


All great truths begin as blasphemies

I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth.


This message is a reply to:
 Message 269 by john6zx, posted 06-29-2008 6:55 AM john6zx has replied

Replies to this message:
 Message 319 by john6zx, posted 07-13-2008 6:33 PM onifre has replied

  
onifre
Member (Idle past 2187 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 280 of 327 (473521)
06-30-2008 12:10 PM
Reply to: Message 276 by cavediver
06-29-2008 6:52 PM


Re: ?????
It is not that we are seeing the distant galaxies and quasars moving away at velocities that they were moving away from us at that time,

Is the speed at which we observe distant galaxies moving at, since it is said that further galaxies are moving away at greater velocities, due to spacetimes curvature and our obsevational point?

IOW, is the space between galaxies expanding at the same rate?

I hope my question makes sense...


All great truths begin as blasphemies

I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth.


This message is a reply to:
 Message 276 by cavediver, posted 06-29-2008 6:52 PM cavediver has taken no action

Replies to this message:
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New Cat's Eye
Inactive Member


Message 281 of 327 (473550)
06-30-2008 3:42 PM
Reply to: Message 280 by onifre
06-30-2008 12:10 PM


Re: ?????
Is the speed at which we observe distant galaxies moving at, since it is said that further galaxies are moving away at greater velocities, due to spacetimes curvature and our obsevational point?

IOW, is the space between galaxies expanding at the same rate?

I hope my question makes sense...

Take a rubber band and draw 7 dots on it, equally spaced apart. The middle one represents our galaxy while the others represent other galaxies. When you stretch out the rubber band, the dots that are farther from the middle one move farther and faster away from the dots that are closer to the middle one even though the rubber band is stretching by the same amount across all the dots.

The distance and speeds are compounded by the space between our galaxy and the nearest one and the distance between the nearest one and the farther ones.

Make sense?

IOW, is the space between galaxies expanding at the same rate?

Yes.


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 Message 280 by onifre, posted 06-30-2008 12:10 PM onifre has replied

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onifre
Member (Idle past 2187 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 282 of 327 (473557)
06-30-2008 5:10 PM
Reply to: Message 281 by New Cat's Eye
06-30-2008 3:42 PM


Re: ?????
The distance and speeds are compounded by the space between our galaxy and the nearest one and the distance between the nearest one and the farther ones.

Make sense?

Yes, and the rubber band analogy was the same as I was shown last semester, they just never further explained it during the lecture since it was off topic to the lecture. It just now made more sense since you further explained how spacetimes'curvature makes it seem faster from our POV. Its an Euclidean geometric sphere that our Universe resembles...thats simpler now to understand.

The rubber band analogy then is almost like the infinity question of whats greater?,

1,2,3,4,5,6...
or
2,4,6,8,10...

its all equal.

Yes.

Cool. Yeah I figured as much I just didn't know if the speed had any relation to the total mass of a galaxy.

Thanks again.


All great truths begin as blasphemies

I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth.


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 Message 281 by New Cat's Eye, posted 06-30-2008 3:42 PM New Cat's Eye has taken no action

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lyx2no
Member (Idle past 3952 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 283 of 327 (473566)
06-30-2008 6:01 PM
Reply to: Message 282 by onifre
06-30-2008 5:10 PM


Very ?????
The rubber band analogy then is almost like the infinity question of whats greater?,

1,2,3,4,5,6...
or
2,4,6,8,10...

its all equal.

I'm uncertain as to what you mean by this, but it seems you may be reading too much into a mechanical analogy. Can you expound upon it?

Edited by lyx2no, : Punctuation.


Kindly

∞∞∞∞∞∞∞

Everyone deserves a neatly dug grave. It is the timing that's in dispute.


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Straggler
Member (Idle past 205 days)
Posts: 10332
From: London England
Joined: 09-30-2006


Message 284 of 327 (473568)
06-30-2008 6:23 PM
Reply to: Message 276 by cavediver
06-29-2008 6:52 PM


Re: ?????
There is actually a far far simpler explanation

I read this and was pathetically optimistic that I would be able to understand.

As you may know, photons actually have no "length", as the proper distance between the emission and absorption of a photon is zero (think of infinite length contraction), and there is no time between emission and absorption (think of infinite time dilation.)

As "particle" travelling at the speed of light this makes sense in terms of my understanding of SR. So far so good.

So how does the red-shift arise in this context?

That is the question I am asking. So again I am optimistic regarding my comprehension.

It is simply a result of the light-cone at emission pointing in a different direction to the light cone at absorption. The photon allows us to overlap the light cones (despite being separated in our minds by billions of years and billions of light-years) and take a measurement of the difference between them.

I am lost :(
How do we take a measurment of the difference between light cones?
I can envisage the emission light cone. Ditto the absorption light cone. I can even imagine the merging of the two to form two cones base to base.

But I am utterly lost as to how this relates to the red shift?
Can you explain further?


This message is a reply to:
 Message 276 by cavediver, posted 06-29-2008 6:52 PM cavediver has replied

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cavediver
Member (Idle past 2879 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 285 of 327 (473573)
06-30-2008 7:11 PM
Reply to: Message 284 by Straggler
06-30-2008 6:23 PM


Re: ?????
It is simply a result of the light-cone at emission pointing in a different direction to the light cone at absorption. The photon allows us to overlap the light cones (despite being separated in our minds by billions of years and billions of light-years) and take a measurement of the difference between them.

I am lost
How do we take a measurment of the difference between light cones?
I can envisage the emission light cone. Ditto the absorption light cone. I can even imagine the merging of the two to form two cones base to base.

But I am utterly lost as to how this relates to the red shift?
Can you explain further?

Ok, let's say I have a light source - that wavelength/frequency of the light is measured relative to the time axis of my own light-cone. Relative to a light-cone that is tipped over somewhat, the light will appear to have a longer wavelength, lower frequency, and hence red-shift, because the ticks of a clock measured in the first light cone, will tick more slowly when measured against the time axis of the second light cone (and vice-versa). Cosmological curvature is what causes the two light cones to be tipped wrt each other, and the photon joining the two light cones is what enables us to compare their relative tipping.

Edited by cavediver, : No reason given.


This message is a reply to:
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