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KhashayarShatti
2012-May-18, 07:35 PM
There seems to be some misconception regarding the following questions?
1- Is dark energy mainstream or ATM?
2- Is Receding of galaxies a kind of scientific motion or ATM?
3- Is the expansion of space(universe) higher than SOL scientific or ATM?
4- Is this question scientific or ATM? What is the actual cause of the motion of matter with respect to space?

Strange
2012-May-18, 08:44 PM
There seems to be some misconception regarding the following questions?
1- Is dark energy mainstream or ATM?

Mainstream but hypothetical - a "place holder" for something we don't yet understand.


2- Is Receding of galaxies a kind of scientific motion or ATM?

Solidly mainstream: predicted by theory and then observed.


3- Is the expansion of space(universe) higher than SOL scientific or ATM?

Mainstream (but really a misunderstanding - nothing is moving faster that light).


4- Is this question scientific or ATM? What is the actual cause of the motion of matter with respect to space?

There is no one answer to that. For one thing, we can only measure motion relative to something else. Also, if something is moving at a constant velocity, there is no need for a "cause". A force is only needed to make something change velocity.

ShinAce
2012-May-18, 10:59 PM
There seems to be some misconception regarding the following questions?

Why take some simple questions and make them loaded questions by putting that line at the beginning? edit: I was going to ask why you don't ask these follow-up questions in your existing threads, but having located the old thread, I see why. I'll leave what I wrote, but I want you to know that you do not need to answer my question. Please think about it though.

1) Dark energy is mainstream.
2) Define scientific motion, please.
3) The expansion is not faster than light. The expansion must be applied to the whole universe, not just one really distant galaxy. Imagine you point a laser at the moon and then shake the laser a bit. The spot that is on the moon may look like it's moving faster than light. All that means is that this thing you call a 'spot' can be given a speed higher than light. Light itself goes the speed of light. The distant galaxy is the spot.
4) That is a scientific question, that has been covered for you. Accelerated motion is the result of forces acting on matter. No forces, no acceleration. No acceleration, no cool forms of motion, just coasting. Repeating the same question again and putting 'actual' in the sentence doesn't change its meaning. I digress, implying that the answers given are untrue because you want to know the 'actual' reason is not scientific.

KhashayarShatti
2012-May-19, 02:09 PM
So confusing!
Referring to the following paragraph from the following site:

"While special relativity constrains objects in the universe from moving faster than the speed of light with respect to each other, there is no such theoretical constraint when space itself is expanding. It is thus possible for two very distant objects to be expanding away from each other at a speed greater than the speed of light. Since the parts of the universe cannot be seen after their speed of expansion away from us exceeds the speed of light, the size of the entire universe could be greater than the size of the observable universe."
http://en.wikipedia.org/wiki/Metric_expansion_of_space
It is clearly stating a true motion faster than the speed of light.

slang
2012-May-19, 03:37 PM
So confusing!
Referring to the following paragraph from the following site:

"While special relativity constrains objects in the universe from moving faster than the speed of light with respect to each other, there is no such theoretical constraint when space itself is expanding. It is thus possible for two very distant objects to be expanding away from each other at a speed greater than the speed of light. Since the parts of the universe cannot be seen after their speed of expansion away from us exceeds the speed of light, the size of the entire universe could be greater than the size of the observable universe."
http://en.wikipedia.org/wiki/Metric_expansion_of_space
It is clearly stating a true motion faster than the speed of light.

The word "true" is not on that page. How is it "clearly stating a true motion faster than the speed of light"? That's your interpretation at work, is it not?

It DOES clearly state that "a speed greater than the speed of light" [is thus possible] "for two very distant objects". Not local objects. Just vastly, hugely, mind-bogglingly distant objects.

KhashayarShatti
2012-May-19, 04:03 PM
The word "true" is not on that page. How is it "clearly stating a true motion faster than the speed of light"? That's your interpretation at work, is it not?

It DOES clearly state that "a speed greater than the speed of light" [is thus possible] "for two very distant objects". Not local objects. Just vastly, hugely, mind-bogglingly distant objects.

Right. If I've understood it properly , it says and as you say, a distant galaxy is moving away from us at a speed greater than the SOL, yes?
I'm trying very hard not to make it ATM. What i'm trying to understand is this. Is it possible to have local inflation? May be this is not a good question; let me put it this way: Is it possible to scientifically create a similar condition for close objects(no strong gravity around)? I know that dark energy is not so much known yet but mainstream confirms its existence.
In general: Is there any scientific possibility of local expansion of space, opposite to local distorsion of space as Einstein refers to it?

ShinAce
2012-May-19, 04:17 PM
The mainstream of that is called the Big Rip. In that case, lambda is less than one.

Most physicists try to make the critical density, lambda, equal to one.

It'll take a while to see it, but eventually you will find that two objects moving away from each other at faster than light are casually disconnected. Whether you fall through an event horizon or notice that galaxies start disappearing. For now, they are not disappearing. More galaxies are appearing, at least they should. That tells me that on the whole, we are not in a big rip.

slang
2012-May-19, 04:20 PM
Right. If I've understood it properly , it says and as you say, a distant galaxy is moving away from us at a speed greater than the SOL, yes?

No, it does not, and I do not. The text you quoted says "it is expanding away". Not moving. There is a subtle, but very important difference.


I'm trying very hard not to make it ATM. What i'm trying to understand is this. Is it possible to have local inflation?

I think you mean expansion, not inflation.


May be this is not a good question; let me put it this way: Is it possible to scientifically create a similar condition for close objects(no strong gravity around)? I know that dark energy is not so much known yet but mainstream confirms its existence.
In general: Is there any scientific possibility of local expansion of space, opposite to local distorsion of space as Einstein refers to it?

Is the solar system local enough? Why don't we ask Ned Wright?

Why doesn't the Solar System expand if the whole Universe is expanding? (http://www.astro.ucla.edu/~wright/cosmology_faq.html#SS)

KhashayarShatti
2012-May-19, 04:44 PM
The mainstream of that is called the Big Rip. In that case, lambda is less than one.

Most physicists try to make the critical density, lambda, equal to one.

It'll take a while to see it, but eventually you will find that two objects moving away from each other at faster than light are casually disconnected. Whether you fall through an event horizon or notice that galaxies start disappearing. For now, they are not disappearing. More galaxies are appearing, at least they should. That tells me that on the whole, we are not in a big rip.

As far as I can understand the big rip, a similar analogy tells me it is something related to the amount of bending of space. If you think of the energy of the side lobes of a communication transmitter antenna, some slight deviation reduces the power a lot, so if science refers to bending of space, is it not ATM to think of the straightening of space? Perhaps this is what Flat Universe refers to it, but why in science world no one speaks of straightening of space. I hope I have not entered ATM.
Perceptually it seems to me that gravity is related to bending of space and dark energy is related to straightening of space. Is this right?

Van Rijn
2012-May-19, 11:02 PM
I know that dark energy is not so much known yet but mainstream confirms its existence.


Be careful there: It's generally accepted that observation supports accelerating expansion, but what causes it is unclear and discussions can (and often do) move quickly into ATM. As Strange mentioned earlier, "dark energy" is a place holder term. Don't assume anything is established beyond the observational arguments.

KhashayarShatti
2012-May-20, 02:26 PM
Be careful there: It's generally accepted that observation supports accelerating expansion, but what causes it is unclear and discussions can (and often do) move quickly into ATM. As Strange mentioned earlier, "dark energy" is a place holder term. Don't assume anything is established beyond the observational arguments.
Absolutely right. Thanks. The analogy exists in parallel lines. If two infinitely long parallel lines can never and never cross one another, then the slightest deviation of the lines, will bring the crossing points billions of kilometers closer. Is it possible to think that bending of space may have similar effect? I mean if bending is reduced, as ShinAce also refers to it, things get more disconnected and perhaps separated billions of kilometers! Yes?

KhashayarShatti
2012-May-20, 02:35 PM
Please note an interesting site:
http://www.ufodigest.com/propulsion.html

Perikles
2012-May-20, 02:44 PM
Please note an interesting site:
http://www.ufodigest.com/propulsion.htmlWhy is this interesting?


This is exactly how UFOs travel from one destination to another.
So now we know.

Strange
2012-May-20, 02:51 PM
Please note an interesting site:
http://www.ufodigest.com/propulsion.html

That is just fantasy. (The source should be a strong clue.)

Shaula
2012-May-20, 02:55 PM
Please note an interesting site:
http://www.ufodigest.com/propulsion.html
No, it really isn't very interesting. It is a series of assertions and pointless speculation with no evidence. It mentions the oft discussed concept of warp drives which is I guess why you think it is interesting - I'd recommend reading other sources. Preferably ones that do not start with the premise the UFOs are alien spacecraft and ones that contain more background to the theory of the drives. This Wiki page (http://en.wikipedia.org/wiki/Alcubierre_drive) is a nice start and doesn't require you to wade through UFO-based prose to get to anything relevant.

KhashayarShatti
2012-May-20, 02:56 PM
Is the first paragraph scientific or a kind of ATM? (It says scientists and engineers).

Strange
2012-May-20, 03:06 PM
Is the first paragraph scientific or a kind of ATM? (It says scientists and engineers).

It says scientists and engineers. It doesn't name them and it doesn't provide any references to the research it claims they are doing. It is clearly just a fabricated story.

KhashayarShatti
2012-May-20, 03:09 PM
No, it really isn't very interesting. It is a series of assertions and pointless speculation with no evidence. It mentions the oft discussed concept of warp drives which is I guess why you think it is interesting - I'd recommend reading other sources. Preferably ones that do not start with the premise the UFOs are alien spacecraft and ones that contain more background to the theory of the drives. This Wiki page (http://en.wikipedia.org/wiki/Alcubierre_drive) is a nice start and doesn't require you to wade through UFO-based prose to get to anything relevant.

You are quite right. I thought so because it refers to UFOs. But more interesting is the Wiki page you referred to. It says:
The object(s) within the bubble are not moving (locally) faster than light, instead, the space around them shifts so that the object(s) arrives at its destination faster than light would in normal space.[2]. Is this a scientifically called motion? Well many referred to motion caused by force and energy. What do you call this kind of separation of objects?

ShinAce
2012-May-20, 03:47 PM
I mean if bending is reduced, as ShinAce also refers to it, things get more disconnected and perhaps separated billions of kilometers! Yes?

Perhaps Alzheimer's has set in for me, but I never said that. Show me where I 'also refer to' the reduction of bending.

Your concept of motion needs some fine tuning. There is a wiki page for motion:
http://en.wikipedia.org/wiki/Motion_(physics)

You can read it yourself and find this paragraph:

Spacetime (the fabric of the universe) is actually expanding. Essentially, everything in the universe is stretching like a rubber band. This motion is the most obscure as it is not physical motion as such, but rather a change in the very nature of the universe. The primary source of verification of this expansion was provided by Edwin Hubble who demonstrated that all galaxies and distant astronomical objects were moving away from us ("Hubble's law") as predicted by a universal expansion.

I wonder what they mean by "it is not physical motion as such".

KhashayarShatti
2012-May-20, 04:10 PM
Perhaps Alzheimer's has set in for me, but I never said that. Show me where I 'also refer to' the reduction of bending.


Ah my fault. I wanted to relate "objects get casually disconnected" part of what you said to bending of space "as ShinAce also refers to it, things get more disconnected", Obviously you didn't say anything about the bending of space or " more disconnected". Sorry my fault.

Shaula
2012-May-20, 04:45 PM
The object(s) within the bubble are not moving (locally) faster than light, instead, the space around them shifts so that the object(s) arrives at its destination faster than light would in normal space.
And that is the critical bit - it is simplistic to say "objects cannot move faster than light". GR does not say that - it merely say that you cannot locally move faster than the speed of light.