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KhashayarShatti
2012-Jun-07, 03:55 PM
From a scientific point of view, generally it is said that BH is defined as a source of suction of matter only. Is there the possibility that space may be sucked into BH in which case the suction of matter takes place similar to a vacuum cleaner? Perhaps it may not be similar to a kind of flow, but suction of space may become stabilized by the reaction of space creating a kind of space differential contour easing the fall of matter. As far as i can see artistic photos of BH swallowing stars, it makes me think of some scientific facts behind it!

antoniseb
2012-Jun-07, 04:00 PM
From a scientific point of view, generally it is said that BH is defined as a source of suction of matter only. ...

Can you cite *any* source for this assertion? Several parts of this statement don't match with my understanding of how it works, but you and I might be having a terminology problem.

KhashayarShatti
2012-Jun-07, 04:23 PM
Can you cite *any* source for this assertion? Several parts of this statement don't match with my understanding of how it works, but you and I might be having a terminology problem.

http://en.wikipedia.org/wiki/Black_hole
"Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies."

Strange
2012-Jun-07, 04:28 PM
From a scientific point of view, generally it is said that BH is defined as a source of suction of matter only.

It is just gravity. Nothing special.


Is there the possibility that space may be sucked into BH in which case the suction of matter takes place similar to a vacuum cleaner?

Space isn't "stuff" that can be sucked into a black hole. Gravity can be described in terms of geometry: as the curvature of space time. This curvature changes the path of objects and causes the force of gravity. At the horizon of a black hole this curvature becomes so great that light cannot escape.

But there isn't any actual space-time "stuff" being curved; it is just a mathematical description.

slang
2012-Jun-07, 04:42 PM
http://en.wikipedia.org/wiki/Black_hole
"Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. There is general consensus that supermassive black holes exist in the centers of most galaxies."

Where is the word 'suction' in there? And a black hole will happily absorb a foton too, no mass there!

Ara Pacis
2012-Jun-07, 04:56 PM
Suction is caused by pressure. There is no pressure in space.

KhashayarShatti
2012-Jun-07, 05:05 PM
It is just gravity. Nothing special.



Space isn't "stuff" that can be sucked into a black hole. Gravity can be described in terms of geometry: as the curvature of space time. This curvature changes the path of objects and causes the force of gravity. At the horizon of a black hole this curvature becomes so great that light cannot escape.

But there isn't any actual space-time "stuff" being curved; it is just a mathematical description.

Bending of light also occurs when light enters different mediums the most famous one being when light enters water. A very clear bending occurs. This is in fact a proven scientific fact, but the validity of mathematical description of space may not be currently a proven scientific fact. So if space is not sensed as a medium of ingredients, there should be at least some proof of the wrong validity of refractive index of vacuum. I cannot find such a proof from scientific documents to convince myself though it may turn out to be wrong but scientifically this case should be rejected by a kind of proof.

Strange
2012-Jun-07, 05:14 PM
Bending of light also occurs when light enters different mediums the most famous one being when light enters water. A very clear bending occurs.

I'm not sure how that is relevant...


This is in fact a proven scientific fact, but the validity of mathematical description of space may not be currently a proven scientific fact.

Well, apart from there is no such thing as a "proven scientific fact", the description of gravity as curvature of spacetime has been very thoroughly tested and is as close to "fact" as science every gets.


So if space is not sensed as a medium of ingredients, there should be at least some proof of the wrong validity of refractive index of vacuum.

The refractive index of vacuum is 1, by definition. But, again, I'm not sure how this is relevant.


I cannot find such a proof from scientific documents to convince myself though it may turn out to be wrong but scientifically this case should be rejected by a kind of proof.

I'm sorry. I don't understand that. I'm not even sure what you are looking for.

KhashayarShatti
2012-Jun-07, 05:26 PM
......
I'm sorry. I don't understand that. I'm not even sure what you are looking for.

In gravitational lensing light is said to bend due to gravity, but generally it is not described by spectral components of light, only bending is generally cited. These two cases of bending of space-time and a medium with refractive index seem to be so similar that to prove one against the other seems to have been either neglected or impossible.
A light bow in the sky is a good proof of bending of light as it enters different gaseous medium of air.

Swift
2012-Jun-07, 05:30 PM
In gravitational lensing light is said to bend due to gravity, but generally it is not described by spectral components of light, only bending is generally cited. These two cases of bending of space-time and a medium with refractive index seem to be so similar that to prove one against the other seems to have been either neglected or impossible.
A light bow in the sky is a good proof of bending of light as it enters different gaseous medium of air.
No, the bending of light by refraction and the bending of light by gravity (curvature of space-time) are completely different phenomena. And, as Strange said, the bending of light by the curvature of space-time has been experimentally shown multiple times.

Strange
2012-Jun-07, 05:35 PM
In gravitational lensing light is said to bend due to gravity, but generally it is not described by spectral components of light, only bending is generally cited. These two cases of bending of space-time and a medium with refractive index seem to be so similar that to prove one against the other seems to have been either neglected or impossible.

Completely different. For example, the bending of light by changing refractive index causes "dispersion"; the amount of bending varies with wavelength. This is why we get a spectrum out of a prism. This is not the case for gravitational lensing.

Ara Pacis
2012-Jun-07, 05:49 PM
Actually, gravity doesn't bend light. It bends space. Light is following a straight path through bent space and that makes it seem bent to us, but that's because we're in a different frame of reference. Refraction, on the other hand, occurs at density interfaces between different media and different frequencies are refracted at different angles.

Also, is it proper to say that vacuum is a medium or would it be better to say that vacuum is the absence of medium? I'm not sure.

KhashayarShatti
2012-Jun-07, 06:05 PM
Completely different. For example, the bending of light by changing refractive index causes "dispersion"; the amount of bending varies with wavelength. This is why we get a spectrum out of a prism. This is not the case for gravitational lensing.

So do you mean that there is no chromatic aberration of light due to bending of space-time around a galaxy or a star? Would you please give a reference. I tried to find one but i couldn't find a mainstream one.

Strange
2012-Jun-07, 06:17 PM
So do you mean that there is no chromatic aberration of light due to bending of space-time around a galaxy or a star? Would you please give a reference. I tried to find one but i couldn't find a mainstream one.

I'm not sure how to find a reference for something that doesn't exist!

On the other hand, the refractive index of (most) materials is frequency dependent: http://en.wikipedia.org/wiki/Dispersion_%28optics%29

Cougar
2012-Jun-07, 07:35 PM
But there isn't any actual space-time "stuff" being curved; it is just a mathematical description.

Then how is frame-dragging explained? These "mathematical descriptions" describe what is observed.

Strange
2012-Jun-07, 07:50 PM
Then how is frame-dragging explained? These "mathematical descriptions" describe what is observed.

They describe the (changing) geometry of space-time.

I don't think of space-time as a material substance though (despite the fact I have just had Einstein's "according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an ether" quote thrown at me in another forum).

ngc3314
2012-Jun-07, 09:56 PM
So do you mean that there is no chromatic aberration of light due to bending of space-time around a galaxy or a star? Would you please give a reference. I tried to find one but i couldn't find a mainstream one.

Correct - gravitational deflection and lensing are achromatic (at least until one reaches the extreme limiting case where the wavelength of radiation is comparable to the impact parameter with respect to the mass, so the ray-tracing technique of pure geometric optics will break down). This is sufficiently common knowledge that a Google Scholar search for "gravitational lensing achromatic" generates over 1700 references.

Reality Check
2012-Jun-08, 01:23 AM
So do you mean that there is no chromatic aberration of light due to bending of space-time around a galaxy or a star? Would you please give a reference. I tried to find one but i couldn't find a mainstream one.
Wikipedia is your friend!
Gravitational lens (http://en.wikipedia.org/wiki/Gravitational_lens)
The angle of deflection is 4GM/rc^2 toward the mass M at a distance r from the affected radiation, where G is the universal constant of gravitation and c is the speed of light in a vacuum.
Note that there is no dependence on wavelength.

This makes sense because the deflection in GR is caused by geometry which affects all wavelengths of light equally (they all follow the same geodesic).

KhashayarShatti
2012-Jun-08, 05:54 AM
Wikipedia is your friend!
Gravitational lens (http://en.wikipedia.org/wiki/Gravitational_lens)
The angle of deflection is 4GM/rc^2 toward the mass M at a distance r from the affected radiation, where G is the universal constant of gravitation and c is the speed of light in a vacuum.
Note that there is no dependence on wavelength.

This makes sense because the deflection in GR is caused by geometry which affects all wavelengths of light equally (they all follow the same geodesic).

You see it states that the speed of light is assumed to be constant, but in the following article it seems to refer to the bending of light as a consequence of the delay of light and so a change of speed.
http://www.astro.ucla.edu/~wright/deflection-delay.html
I think this article should be valid belonging to UCLA, it also refers to some statements from Einstein.
Although in the animation, the observer is not shown to sense side dispersion but a kind of delay in arrival of red and green and black(what is a black light?) light could be sensed.

Shaula
2012-Jun-08, 06:37 AM
The red green and black components there are using different models. It says so in the key to the diagram, has nothing to do with colours of light.

KhashayarShatti
2012-Jun-08, 07:11 AM
The red green and black components there are using different models. It says so in the key to the diagram, has nothing to do with colours of light.
Right. I didn't notice this"the black showing the situation when the Sun is not close to the star". So in fact the star is seen by the observer at many different positions which are shown by different colours. Now has it been experimentally observed that there is no dispersion of light in this situation where there is the combination of these lights from deflection and delay or is it a mathematical proof? You know that the gaseous state of matter around stars or galaxies does cause some dispersion which may make observation difficult to analyze the situation which only concerns the bending due to space-time.

Ara Pacis
2012-Jun-08, 07:23 AM
Right. I didn't notice this"the black showing the situation when the Sun is not close to the star". So in fact the star is seen by the observer at many different positions which are shown by different colours. Now has it been experimentally observed that there is no dispersion of light in this situation where there is the combination of these lights from deflection and delay or is it a mathematical proof? You know that the gaseous state of matter around stars or galaxies does cause some dispersion which may make observation difficult to analyze the situation which only concerns the bending due to space-time.It's not different positions shown by the colors, but different predictions based on two different mathematical models of the sun present, and one without the sun present for baseline comparison. Newtonian prediction does not, by observation, actually occur as light tends to more closely follow the Einsteinian prediction.

KhashayarShatti
2012-Jun-08, 09:24 AM
Well. To focus on the main topic, whatever is shown, it is clear that the more the bending of space time , the more the effect of gravity. So in a physical sense gravity exists more closer to the surface of BH or a star.
In real sense there is the motion of matter being dragged into BH which is said to be due to bending of space time.It means that bending of space-time is the cause of motion which has a physical sense; it is acting as a force rising from a kind of energy to generate motion. In this case matter itself is not causing the actual motion, the space itself is causing this motion. My question is : could there be less space around BH(due to absorption of space by BH similar to absorption of matter by BH) causing straightening of space there and accelerating objects? Although it may be converging situation for matter, but it may be sensed as a situation that shows when there is less space, acceleration of matter may takes place. You see gravity causes acceleration in a converging situation and space expansion causes acceleration in a diverging situation and we know it as a scientific fact.
I'm not sure if i've been able to make it clear what i want to say. Sorry.
Let me puit it this way: Expansion of the universe and gravity have similar effect on the motion of matter, one being diverging the other being converging but both of them seem to rise from the same situation regarding the condition of space. I hope my bad description will not be regarded as ATM.

Strange
2012-Jun-08, 09:54 AM
Well. To focus on the main topic, whatever is shown, it is clear that the more the bending of space time , the more the effect of gravity. So in a physical sense gravity exists more closer to the surface of BH or a star.

Correct. The strength of gravity follows an inverse square law: halve the distance and the force increases by four.


My question is : could there be less space around BH(due to absorption of space by BH similar to absorption of matter by BH) causing straightening of space there and accelerating objects?

It is not that there is "less" space, it is that space & time are more curved so that when things are following a "straight line" they are forced to move towards the the mass. I don't know a good way of visualising this though, I'm afraid.

KhashayarShatti
2012-Jun-08, 12:04 PM
It is not that there is "less" space, it is that space & time are more curved so that when things are following a "straight line" they are forced to move towards the the mass. I don't know a good way of visualising this though, I'm afraid.

Apart from thinking of F=ma, in which acceleration is regarded as force per unit mass, we know that acceleration is dx^2/dt^2 totally defined by distance and time.What is shown in the animation at the bottom of the above web site from ucla, rather a kind of bending in time causes the wavefront to bend.

There are two cases for the above formula for change of speed:Either space remains constant and time reduces or space increases and time remains constant which could be regarded as the main effect of causing the motion of an object from an stationary condition.This also could be regarded as a kind of force but this force rises directly from a change in space-time.

Is it possible to define change of motion as a consequence of change of time or space? Since objects have dimension, when one side of an object experiences a different time then speed and acceleration appear?

cjameshuff
2012-Jun-08, 03:20 PM
So do you mean that there is no chromatic aberration of light due to bending of space-time around a galaxy or a star? Would you please give a reference. I tried to find one but i couldn't find a mainstream one.

A reference stating that something which there is no reason to expect to happen, doesn't happen? Why would you expect to find such a thing?

As you yourself noticed, the equations describing the deflection do not depend on wavelength. Images of the deflection show no sign of chromatic aberration. What do you need a reference for?

trinitree88
2012-Jun-08, 03:27 PM
Suction is caused by pressure. There is no pressure in space.

Hmmmm, Ara.. there is a very, very slight radiation pressure due to the zeropoint radiation and the neutral current scattering by the neutrino sea in all of space.. pete

Shaula
2012-Jun-08, 04:06 PM
we know that acceleration is dx^2/dt^2
No, acceleration is d^2 x / dt^2. It is the second derivative of displacement with respect to time. Not the square of the velocity as you have written.

pzkpfw
2012-Jun-08, 09:29 PM
Apart from thinking of F=ma, in which acceleration is regarded as force per unit mass, we know that acceleration is dx^2/dt^2 totally defined by distance and time.What is shown in the animation at the bottom of the above web site from ucla, rather a kind of bending in time causes the wavefront to bend.

There are two cases for the above formula for change of speed:Either space remains constant and time reduces or space increases and time remains constant which could be regarded as the main effect of causing the motion of an object from an stationary condition.This also could be regarded as a kind of force but this force rises directly from a change in space-time.

Is it possible to define change of motion as a consequence of change of time or space? Since objects have dimension, when one side of an object experiences a different time then speed and acceleration appear?

You clearly have an idea which you are trying to promote (using questions) through this thread. Like most of your threads, this is ATM by stealth. Infraction given.

Ara Pacis
2012-Jun-08, 10:02 PM
Hmmmm, Ara.. there is a very, very slight radiation pressure due to the zeropoint radiation and the neutral current scattering by the neutrino sea in all of space.. peteAh, true. I should have stated that I meant mechanical pressure as in a gas medium.

chiragrav
2012-Jun-09, 02:44 PM
Who would need to stop thinking about this particular phenomenon of gravitational collapse!
Any body have any ideas/thoughts about Hawking Radiation>?

neilzero
2012-Jun-09, 06:04 PM
Perhaps a little light, dark matter, dark energy, zero point energy, random fluctuations and other buzz words fall inside the event horizon of black holes = why not? Apparently the scientific community doesn't like "suck", even though not entirely wrong. Likely even issolated black holes have a very thin accretion disk. The orbits of objects orbiting a blackhole (or any body with an accretion disk) tend to decay at each pass though the accreation disc = more like falling than being sucked. Neil

publiusr
2012-Jun-09, 06:25 PM
Frankly I'd be more afraid of a magnetar than a black hole were I in some kind of spaceship. A black Hole could be orbited. The magnetic field of a magnetar would actually behave more like the popular notion of a black holes gravity I would imagine. That would reach out and grab you.

Strange
2012-Jun-09, 07:02 PM
Apparently the scientific community doesn't like "suck", even though not entirely wrong.

Would you say that we are held down on earth by "suction"?

Ara Pacis
2012-Jun-09, 09:21 PM
Perhaps a little light, dark matter, dark energy, zero point energy, random fluctuations and other buzz words fall inside the event horizon of black holes = why not? Apparently the scientific community doesn't like "suck", even though not entirely wrong. Likely even issolated black holes have a very thin accretion disk. The orbits of objects orbiting a blackhole (or any body with an accretion disk) tend to decay at each pass though the accreation disc = more like falling than being sucked. NeilMore like aerocapture/aerobraking.

pogono
2012-Jun-10, 03:40 PM
Space isn't "stuff" that can be sucked into a black hole. Gravity can be described in terms of geometry: as the curvature of space time. This curvature changes the path of objects and causes the force of gravity. At the horizon of a black hole this curvature becomes so great that light cannot escape.

But there isn't any actual space-time "stuff" being curved; it is just a mathematical description.

I can not agree with this statement.
I would like to support "sucking space-time" as correct explanation.

In my article (http://www.scirp.org/journal/PaperInformation.aspx?paperID=17700) (please, notice, it is part of mainstream science, now) I prove, utilizing Rindler's transformation for spherically symmetric case, there is a way to consider curved space-time as locally accelerated photons!

I show, that by trying to accelerate photons we do not change its velocity, but instead, at the end of all calculations we obtain space-time curvature increase, while photons still move with constant speed of light!

It means, that we may try to reverse Einstein's reasoning as follows:

1. Gravity acts as attracting photons
2. Trying to accelerate photons we obtain space-time curvature increase
3. Space-time curvature change paths of material bodies

Therefore, it may be explained as space-time sucking situation.

Brad2064994
2012-Jun-10, 04:57 PM
After reading this message BH attracts me.I like to know about them more.

Ara Pacis
2012-Jun-10, 10:47 PM
I can not agree with this statement.
I would like to support "sucking space-time" as correct explanation.

In my article (http://www.scirp.org/journal/PaperInformation.aspx?paperID=17700) (please, notice, it is part of mainstream science, now) I prove, utilizing Rindler's transformation for spherically symmetric case, there is a way to consider curved space-time as locally accelerated photons!

I show, that by trying to accelerate photons we do not change its velocity, but instead, at the end of all calculations we obtain space-time curvature increase, while photons still move with constant speed of light!

It means, that we may try to reverse Einstein's reasoning as follows:

1. Gravity acts as attracting photons
2. Trying to accelerate photons we obtain space-time curvature increase
3. Space-time curvature change paths of material bodies

Therefore, it may be explained as space-time sucking situation.

I'm trying to visualize that. From what I surmise, you've just given us a good definition of suck, but by doing so, you've defined it such that the gas-pressure concept of suction should more appropriately be termed "blow". (cue Spaceballs reference) So, if I understand correctly, this would still argue against the OP.

Strange
2012-Jun-10, 11:09 PM
It means, that we may try to reverse Einstein's reasoning as follows:

1. Gravity acts as attracting photons
2. Trying to accelerate photons we obtain space-time curvature increase
3. Space-time curvature change paths of material bodies

Therefore, it may be explained as space-time sucking situation.

You have just reversed the math and swapped cause and effect. Gravity works in the absence of photons so I don't see the point.

pzkpfw
2012-Jun-10, 11:33 PM
... (please, notice, it is part of mainstream science, now) ...

Please clarify that comment. e.g. Has your paper been "approved" by a recognised peer review committee? Has its content be "accepted" (as distinct from published)?

pogono
2012-Jun-11, 08:08 AM
You have just reversed the math and swapped cause and effect. Gravity works in the absence of photons so I don't see the point.
Strange, please show me any place in space without photons ;-)
At least you find there micro-wave background.


Please clarify that comment. e.g. Has your paper been "approved" by a recognized peer review committee? Has its content be "accepted" (as distinct from published)?
pzkpfw, I do not want to hijack the thread talking about my paper, here.
I put below some short explanation. If you expected more, show me right place to do it.

1. My paper was reviewed by 2 professional reviewers and accepted by Editorial Office. It was regular peer-review process. Maybe JMP just use less censorious peers then other Journals.

2. Moreover, here, on BAUT, user Kuroneko already generalized my equations confirming its correctness (covariant and Tensor based). You may see there (http://www.bautforum.com/showthread.php/121539-macaw-caveman1917-discussion-from-an-ATM-thread?p=1991673#post1991673), exactly what I mention above - we may model curved space-time as locally accelerated photons. It is hard to argue with math!

3. Up to now, I got responses from at least 10 professional physicists from the world confirming my equations. If you wish I send you names and emails (I have to ask them, before). They were mostly shocked, but did not find any mistake in my reasoning. With 3 of them I prepare next publication in GR&G Journal. One of them is going to say few words about my approach at conference: Relativity and Gravitation 100 Years after Einstein in Prague (http://ae100prg.mff.cuni.cz/).

I understand, that most of you have problem with my paper. It begun in ATM section and many of you was fighting against my idea. But, please notice two facts:
- present shape of my article is far from first shape of the paper presented in ATM.
- math says, that I have found a way to consider photon acceleration even if you judge it is ridiculous.

ETA:
For those, who do not want to follow Kuroneko reasoning, here are final Conclusions:


We've just seen that the following are all related:
gravitational acceleration ⇄ gravitational gamma or redshift ⇐ timelike Killing field, and similar but more complicated situation applies to stationary spacetime.
(...) we can do a backwards derivation of Schwarzschild spacetime using an additional free-falling velocity vr = sqrt(rs/r) (...)



Conclusion: The gravitational action of a static spacetime is equivalent to the action of a 3-dimensional spacelike manifold minimally coupled to a scalar field.

It means exactly, what I mention here.

KhashayarShatti
2012-Jun-12, 04:17 PM
You clearly have an idea which you are trying to promote (using questions) through this thread. Like most of your threads, this is ATM by stealth. Infraction given.
I was banned up to now to say: Honestly not true, no intention of ATM by stealth.

Swift
2012-Jun-12, 05:12 PM
I was banned up to now to say: Honestly not true, no intention of ATM by stealth.
KhashayarShatti

Let me make something clear. It doesn't really matter if it was by stealth or not. It is fine to ask a question or ask a question about an idea you might have. But when you are given the mainstream answer, when you are told that your idea is not correct by mainstream science, and then you continue to argue that idea or question the mainstream answer you are given, then you have crossed the line and are advocating ATM. If you do this, you will be infracted.

Now please, do not post further about our moderation or your infractions in this thread.

KhashayarShatti
2012-Jun-13, 07:21 PM
I have one more question to ask. Obviously i do not presume that there must definitely be an answer for my question. This forum is really fine to get updated in mainstream science which is otherwise difficult to get up to date by just reading web sites.
My question is:
Could there be correlation between the position of objects and the curvature of space-time around them? To make it more clear, I assume two cases:
1- If gravity acts as a kind of force and it is said to be related to the curvature of space, does it mean that if curvature of space could hypothetically change at once, the position of the object would change accordingly to obtain a new position that fits the curvature around it?
2- If properties of an object(speed) hypothetically change at once, does the object try to find a new position or curvature of space-time to suit its new properties?

KhashayarShatti
2012-Jun-14, 06:32 PM
You have just reversed the math and swapped cause and effect......
Generally , force doesn't seem to have an understandable microscopic meaning. If we think about it, energy in a peculiar way causes force, but sometimes perhaps it would be more understandable to say that acceleration appears first which gives the feeling of force. In this case we could say a*m =F rather than F=a*m.
When we pin point on the true nature of motion, it seems to me that when some sort of space-time change occurs, it produces acceleration which could be termed as force. As an example, when someone wants to start to walk, it is said that energy is used to create force, but when we deeply focus on how this force is generated, we realize that internally at microscopic scales some sort of change in space perhaps takes place which causes acceleration and accordingly a kind of motion by force. Sometimes we may have to swap cause and effect.
Another example: Electrostatic force and magnetic force, may have similar effects by causing a kind of change in space and hence, dx/dt and then d^2x/dt^2(Shaula thanks for your mentioning correct terminology). In this case all forces of nature may have similar definition and rising from change in space-time.

cjameshuff
2012-Jun-14, 07:27 PM
Generally , force doesn't seem to have an understandable microscopic meaning.

What? It doesn't matter if you're looking at microscopic or macroscopic scales. Different forces may dominate, but the concept has the same meaning.



If we think about it, energy in a peculiar way causes force,

A misleading if not just wrong way to look at things. Energy is a conserved quantity with various relationships to force that depend on the system you are looking at.



but sometimes perhaps it would be more understandable to say that acceleration appears first which gives the feeling of force. In this case we could say a*m =F rather than F=a*m.

...those equations define a relationship between quantities. They don't imply any sort of sequential ordering or cause and effect relationship.



When we pin point on the true nature of motion, it seems to me that when some sort of space-time change occurs, it produces acceleration which could be termed as force. As an example, when someone wants to start to walk, it is said that energy is used to create force, but when we deeply focus on how this force is generated, we realize that internally at microscopic scales some sort of change in space perhaps takes place which causes acceleration and accordingly a kind of motion by force. Sometimes we may have to swap cause and effect.
Another example: Electrostatic force and magnetic force, may have similar effects by causing a kind of change in space and hence, dx/dt and then d^2x/dt^2(Shaula thanks for your mentioning correct terminology). In this case all forces of nature may have similar definition and rising from change in space-time.

What kind of "change in space-time"? How is this at all a useful way to look at things?

Your understanding of the fundamentals is incorrect, and your conclusions are variously either wrong or meaningless. I suggest learning more of basic physics before trying to redefine it.

Strange
2012-Jun-14, 07:42 PM
Could there be correlation between the position of objects and the curvature of space-time around them?

Yes. Mass causes spacetime to curve. The curvature of spacetime determines hoe mass moves.


1- If gravity acts as a kind of force and it is said to be related to the curvature of space, does it mean that if curvature of space could hypothetically change at once, the position of the object would change accordingly to obtain a new position that fits the curvature around it?

I would suggest you consider gravity as either a force (the Newtonian model) or as curvature of spacetime (the GR model) but not both. Otherwise you will get hopelessly confused.

Also, nothing can change "at once" because nothing can move faster than light.


2- If properties of an object(speed) hypothetically change at once, does the object try to find a new position or curvature of space-time to suit its new properties?

I'm not quite sure what you mean. But if you change the mass of a planet, say, (but not "at once" it will take time) then the planet will move to a new orbit. You can consider this to be either because the forces have changed or, equivalently, because spacetime curvature has changed.

ShinAce
2012-Jun-14, 07:51 PM
If all forces of nature arise from changing space-time, why does gravity not care about the material, but the other forces do? Why does gravity only attract, when electromagnetism can attract and repel? If that were true, why are some forces conservative and others are not?

Are we forgetting about the 'path of least resistance' and how potentials are linked to forces? Forces are not changes in spacetime, they are changes in potentials. The result of work being done.

Ara Pacis
2012-Jun-14, 07:59 PM
Why does gravity only attract, when electromagnetism can attract and repel?Figure that one out and you'll get a Nobel Prize and some schools named after you.

Amber Robot
2012-Jun-14, 08:48 PM
Ah, true. I should have stated that I meant mechanical pressure as in a gas medium.

There's a lot of gas in space. So there's pressure there. Just not a lot compared to here on Earth.

Ara Pacis
2012-Jun-15, 12:39 AM
There's a lot of gas in space. So there's pressure there. Just not a lot compared to here on Earth.I'm not talking about space, I'm talking about vacuum.

KhashayarShatti
2012-Jun-15, 06:43 AM
If all forces of nature arise from changing space-time, why does gravity not care about the material, but the other forces do? Why does gravity only attract, when electromagnetism can attract and repel? If that were true, why are some forces conservative and others are not?.....

These are kind of questions i mentioned earlier that may not have a mainstream answer, but when I think about the process that converts science to mainstream science, I find out that there should be some difference between ATM and this process. From mainstream point of view, there is some ability that causes the expansion of universe, I'm not sure if I could describe it this way without falling into ATM out of ATM. That is this: The universe, or lets say space-time generally may have the ability to expand without gravity or attractive forces present and naturally act as being repulsive. In this case there might be the ability of gravity to stabilise the universe(a sort of control mechanism). The key solution seems to exist in the controlled expansion of the universe. Now Any ability to intensify or weaken this or reverse this repulsive force may rise from some change in space-time.
If galaxies are receding from each other and have pull of gravity then there is bound to be a surface boundary around galaxies where gravity and expansion of space neutralize one another, and one goes from attraction effect to repulsion effect. Has anybody calculated this neutral boundary around galaxies? Perhaps two galaxies crossing this boundary could fall into attraction.
Conservation may rise from the ability to convert one form to another. Please note that I'm not trying to develop my idea, but more I'm thinking how science may then become mainstream science?

Amber Robot
2012-Jun-15, 04:13 PM
I'm not talking about space, I'm talking about vacuum.

You said "There is no pressure in space." in an earlier post. So, I thought you were talking about space. My apologies. If you're talking about some theoretical vacuum, then yes, there would be no mechanical pressure there.

Hornblower
2012-Jun-15, 04:32 PM
These are kind of questions i mentioned earlier that may not have a mainstream answer, but when I think about the process that converts science to mainstream science, I find out that there should be some difference between ATM and this process. From mainstream point of view, there is some ability that causes the expansion of universe, I'm not sure if I could describe it this way without falling into ATM out of ATM. That is this: The universe, or lets say space-time generally may have the ability to expand without gravity or attractive forces present and naturally act as being repulsive. In this case there might be the ability of gravity to stabilise the universe(a sort of control mechanism). The key solution seems to exist in the controlled expansion of the universe. Now Any ability to intensify or weaken this or reverse this repulsive force may rise from some change in space-time.
If galaxies are receding from each other and have pull of gravity then there is bound to be a surface boundary around galaxies where gravity and expansion of space neutralize one another, and one goes from attraction effect to repulsion effect. Has anybody calculated this neutral boundary around galaxies? Perhaps two galaxies crossing this boundary could fall into attraction.
Conservation may rise from the ability to convert one form to another. Please note that I'm not trying to develop my idea, but more I'm thinking how science may then become mainstream science?

My bold. Conservation of what? One form of what to another? Please clarify.

Any exercise in science becomes "mainstream" when a preponderance of qualified scientists are satisfied that there is good agreement between theory and observation. Whether or not most of the public at large believes it is beside the point. In the case of Copernicus' revival of a heliocentric theory of planetary orbits, it took well over a century to gain widespread acceptance because of the great difficulty in making the necessary observations. In the case of dark-energy-related cosmic expansion, powerful observing techniques enabled a mainstream acceptance within a few years starting in the 1990s.

As for gravity versus expansion, as I think I understand it, yes there are neutral zones around galaxy clusters. Gravity overpowers the expansion tendency in any volume of space in which there is a dense enough concentration of mass. We don't know the mass distribution well enough to draw sharp boundaries.

KhashayarShatti
2012-Jun-15, 05:17 PM
.....
Also, nothing can change "at once" because nothing can move faster than light....

Good point you referred to. The speed of light. Once a photon is generated(I don't know how much time it takes for a photon to be generated), it has currently the limit of speed in the universe. In this case, light's property corresponds to a spacetime curvature the result of which is what we observe. If there could exist a kind of condensation of photon, perhaps light faces a new spacetime curvature. The question is: Could curvature be the inherent property of objects(case study:light)? In this case may be we could describe energy and force as follows:
1- Energy was created by a change in spacetime(may be from big bang).
2- Any initial force is created by this change of state in spacetime called acceleration.
3- Any motion was created and is created by a change in spacetime. Obviously it may be the result of energy but item 1 gives the answer.
4- Spacetime could be conservative resulting in conservation of energy. I think a non-moving force is generally referred to "energy balance" by conservation, i.e. energy being conservative.
5- Steady state motion could be a balance between spacetime curvature and object properties.
6- Any chemical, mechanical, electrical,... reactions could be the result of a change in spacetime. As an example; explosion by ignition. In this case the electric field of ignition, may change spacetime the result of which could be the release of chemical energy which has already been conserved by spacetime change.

Referring to the above cases, could it be possible to find the main reason that a motion change takes place, for example one can move his/her arm or start walking? Please don't blame me, because my argument is based upon spacetime.

ShinAce
2012-Jun-15, 05:31 PM
You still haven't addressed my questions:

If all forces of nature arise from changing space-time, why does gravity not care about the material, but the other forces do? Why does gravity only attract, when electromagnetism can attract and repel? If that were true, why are some forces conservative and others are not?

Energy is conserved because of a time symmetry. Whether you boil a pot of water today or tomorrow or yesterday(on the same stove, blah blah blah), it will take the same amount of energy.

If I take a single electron and put it in a box, there is a chance it will escape within X seconds. How does spacetime curvature explain quantum tunelling? It doesn't, and it fails in many other places too. How does spacetime curvature explain the vastly different halflives of different isotopes?

KhashayarShatti
2012-Jun-15, 05:41 PM
As for gravity versus expansion, as I think I understand it, yes there are neutral zones around galaxy clusters. Gravity overpowers the expansion tendency in any volume of space in which there is a dense enough concentration of mass. We don't know the mass distribution well enough to draw sharp boundaries.

What is supposed to happen to light at this boundary? Light under different spacetime curvatures, changes speed, but in this case curvature change dramatically at this boundary. Could it be that we may get a change in the speed of light at this boundary?

Strange
2012-Jun-15, 05:50 PM
In this case, light's property corresponds to a spacetime curvature the result of which is what we observe.

Spacetime curvature only determines the path of the photon. t doesn't define its properties.


If there could exist a kind of condensation of photon,

There isn't.


The question is: Could curvature be the inherent property of objects(case study:light)?

No. Curvature is a property of spacetime and is modified by the presence of mass or energy.


In this case may be we could describe energy and force as follows:

1- No
2- No.
3- No.
4- No.
5- No.
6- No.


Referring to the above cases, could it be possible to find the main reason that a motion change takes place, for example one can move his/her arm or start walking?

No.


Please don't blame me, because my argument is based upon spacetime.

I think it is based on your misunderstanding of spacetime. There are some good introductory books that I'm sure someone here could recommend.

ShinAce
2012-Jun-15, 05:52 PM
No, you would get no increase in the speed of light.

If you say that spacetime curvature changes the velocity of light, then the same curvature changes it both ways. Light escaping the sun would be slowed down by the sun's gravity, whereas the cosmic background radiation picks up speed as it falls onto the sun. Changing direction would go from increasing/decreasing. It's not a special place in the universe that would do it. That's only "If you say that spacetime curvature changes the velocity of light", which not many people are going to be comfortable with unless you can show good knowledge of general relativity. The same theory that fails to incorporate all forces as curvature.

Why do you persist on always taking a tangent? How do you learn anything by asking more questions before figuring out any of the previous answers? Everytime I try that, I learn nothing and feel hopelessly lost.

Strange
2012-Jun-15, 05:54 PM
Light under different spacetime curvatures, changes speed

No, it just changes direction.


but in this case curvature change dramatically at this boundary.

There is no sharp boundary. Gravity gradually diminishes with distance (inverse square law). At some point it is not strong enough to overcome the expansion. But the gravity is still there and just carries on reducing by the inverse square law. The bending of light by gravity is quite a small effect and is only visible when light passes very close to a massive object. I assume at the sort of distance from a galaxy cluster we are talking about, the effects on light would be minimal anyway.

ShinAce
2012-Jun-15, 06:03 PM
Technically not a boundary, but a saddle point. A point of zero curvature with curvature on each side. Hypothetically speaking of course, without good constraints on dark matter and dark energy.

KhashayarShatti
2012-Jun-15, 06:07 PM
You still haven't addressed my questions:


Energy is conserved because of a time symmetry. Whether you boil a pot of water today or tomorrow or yesterday(on the same stove, blah blah blah), it will take the same amount of energy.

If I take a single electron and put it in a box, there is a chance it will escape within X seconds. How does spacetime curvature explain quantum tunelling? It doesn't, and it fails in many other places too. How does spacetime curvature explain the vastly different halflives of different isotopes?

You see, I have the same questions for which I'm trying to find answers by asking and being optimistic about the kindness of someone to answer it scientifically. The quantum tunelling I think is one of those questions that has recently concerned some physicists regarding the LENR process in ECAT. By mainstream physics this phenomena is creating some confusion since practically Rossi has shown that something different may exist in this process to counteract the binding energy. However I think If all processes initiate from some kind of spacetime change, then the essence of creation of motion or release of energy could be realized.At a particular configuration of spacetime, quantum tunelling may occur.

Strange
2012-Jun-15, 06:27 PM
Rossi has shown that something different may exist in this process to counteract the binding energy

As far as I know Rossi has demonstrated nothing at all. I would probably be breaching forum rules if I said what I thought he was doing.


At a particular configuration of spacetime, quantum tunelling may occur.

Tunnelling is well understood and explained by quantum physics. As far as I know it does not involve curvature of spacetime.

cjameshuff
2012-Jun-15, 06:33 PM
You see, I have the same questions for which I'm trying to find answers by asking and being optimistic about the kindness of someone to answer it scientifically. The quantum tunelling I think is one of those questions that has recently concerned some physicists regarding the LENR process in ECAT. By mainstream physics this phenomena is creating some confusion since practically Rossi has shown that something different may exist in this process to counteract the binding energy. However I think If all processes initiate from some kind of spacetime change, then the essence of creation of motion or release of energy could be realized.At a particular configuration of spacetime, quantum tunelling may occur.

There is no mainstream confusion about ECAT. There simply aren't any nuclear reactions happening, low-energy or otherwise. Rossi is a fraud, and not a very convincing one. His claims are physically bizarre, he has shown no hard evidence supporting his claims, what evidence he's shown turns out to be clumsily faked (isotope ratios matching natural abundances on Earth, no unstable isotopes), and if there were any truth to his claims there would be unmistakable, impossible-to-fake evidence in the form of huge amounts of radiation for which his shielding would be completely inadequate.

But aside from that, what does your hand waving about "a particular configuration of spacetime" do to explain, describe, or predict quantum tunneling? Or anything else for that matter?

Van Rijn
2012-Jun-15, 08:52 PM
The quantum tunelling I think is one of those questions that has recently concerned some physicists regarding the LENR process in ECAT. By mainstream physics this phenomena is creating some confusion since practically Rossi has shown that something different may exist in this process to counteract the binding energy.

No, there's no confusion. ECat is nonsense. Here's a thread that gets into a good amount of detail on this scam:

http://www.bautforum.com/showthread.php/122685-Whats-up-with-the-Cold-Fusion-Energy-Catalyzer-or-E-Cat/

Rossi has not allowed any verifiable independent tests and his own demos look like fakes (for instance, he demonstrated a device plugged into a wall socket that produces the amont of steam you'd expect if the water were heated conventionally, using a coffee maker or similar). At one time, he said he was going to pay NASA Marshal to test his machine, and that temporarily boosted his credibility, but when it came time to do it, he turned around and demanded NASA pay him $15,000,000. So naturally there was no test.

Ara Pacis
2012-Jun-16, 08:40 AM
You said "There is no pressure in space." in an earlier post. So, I thought you were talking about space. My apologies. If you're talking about some theoretical vacuum, then yes, there would be no mechanical pressure there.Are you saying that there is enough pressure from sparse particlas and isolated atoms to constitute a medium which would convey a pressure as proposed by the OP as being analogous to a vacuum cleaner (ignoring for a second that the solar wind and interplanetary medium are listed as plasmas)? It was my understanding that these atoms and particles are too sparse to interact in the manner typical of what we call gas pressure and instead act as either a particle on an orbital trajectory or they a plasma bound by magnetic fields.

Hornblower
2012-Jun-16, 01:39 PM
Are you saying that there is enough pressure from sparse particlas and isolated atoms to constitute a medium which would convey a pressure as proposed by the OP as being analogous to a vacuum cleaner (ignoring for a second that the solar wind and interplanetary medium are listed as plasmas)? It was my understanding that these atoms and particles are too sparse to interact in the manner typical of what we call gas pressure and instead act as either a particle on an orbital trajectory or they a plasma bound by magnetic fields.

As sparse as it is, interstellar gas still can function as a fluid on scales of many lightyears, when the expanse of the gas is large compared to the mean free path between collisions of the atoms. If a black hole is immersed in such a puff of gas, the gas will fall into it and generate some fireworks from the compressive heating near the hole.

KhashayarShatti
2012-Jun-16, 04:01 PM
But aside from that, what does your hand waving about "a particular configuration of spacetime" do to explain, describe, or predict quantum tunneling? Or anything else for that matter?
I think all atoms vibrate randomly. Does it take place at absolute zero temp?

Tensor
2012-Jun-16, 05:46 PM
I think all atoms vibrate randomly.

Define vibrate in terms of a specific model of atoms.


Does it take place at absolute zero temp?

We won't that until you specific what you mean by "vibrate"

cjameshuff
2012-Jun-16, 06:02 PM
I think all atoms vibrate randomly. Does it take place at absolute zero temp?

It's unclear what you're asking or why you're asking it. What does this have to do with the question you quoted? Or even with the thread topic?

Ara Pacis
2012-Jun-16, 07:22 PM
As sparse as it is, interstellar gas still can function as a fluid on scales of many lightyears, when the expanse of the gas is large compared to the mean free path between collisions of the atoms. If a black hole is immersed in such a puff of gas, the gas will fall into it and generate some fireworks from the compressive heating near the hole."Mean free path" is probably the concept I was grasping at. But the OP is talking about pressure on the scale of a blackhole event horizon, which not be measured in light hears but, what, hundreds to thousands of miles? We had been talking about accretion disk pressure separately, in order not to conflate the two. After all, he was asking about photons.

Amber Robot
2012-Jun-16, 10:52 PM
Are you saying that there is enough pressure from sparse particlas and isolated atoms to constitute a medium which would convey a pressure as proposed by the OP as being analogous to a vacuum cleaner (ignoring for a second that the solar wind and interplanetary medium are listed as plasmas)?

I won't comment about vacuum cleaners, but as Hornblower points out, there is pressure in space. And that is what I was responding to, the comment about no pressure in space.

Hornblower
2012-Jun-17, 01:11 AM
"Mean free path" is probably the concept I was grasping at. But the OP is talking about pressure on the scale of a blackhole event horizon, which not be measured in light hears but, what, hundreds to thousands of miles? We had been talking about accretion disk pressure separately, in order not to conflate the two. After all, he was asking about photons.I think he was talking about something other than gas. I an not sure what that something was supposed to be.

Ara Pacis
2012-Jun-17, 04:04 AM
I won't comment about vacuum cleaners, but as Hornblower points out, there is pressure in space. And that is what I was responding to, the comment about no pressure in space.So, there is no vacuum in space, but apparently comments in a thread exist in a vacuum. Got it.

Ara Pacis
2012-Jun-17, 04:07 AM
I think he was talking about something other than gas. I an not sure what that something was supposed to be.It didn't seem that clear to me. He was conflating a lot of ideas, so it's hard to respond to that without appearing to conflate ideas. One might try making blanket statements that approximate reality so that he might understand the difference and stop conflating them. Or we can attempt a thread of attrition by arguing in the trenches of nitpicking semantics and ignore that part where not only is he not right, he's not even wrong.

KhashayarShatti
2012-Jun-17, 02:01 PM
Tensor, cjameshuff
As far as I can remember from college physics text books, all atoms in a lattice vibrate.
Vibration is thought to be related to temperature, and collision of atoms is related to pressure and stress within lattice(similar to a gas under pressure at a temp above zero kelvin).
Now if there would be suction of spacetime within the lattice which might be the main cause of temp. and press. then this spacetime may vibrate and have +peak and -peak within the lattice. If vibration of individual atoms would be random,then at particular parts of the lattice these peaks may cause peak -curvature and +curvature. These peak +ve or ve- curvatures may provide the ability for quantum tunelling or fusion .For this reason I think inside BH, could exist very heavy elements as well.

It may give a clue if:
1- at zero kelvin, the rate of disintegration may reduce since atoms vibrate less(perhaps zero vibration). Surely experimental results exist to show what happens.

2- at zero kelvin it could be possible to vibrate the lattice in phase and create atomic resonance(I already have said a few words about this in my previous threads)?

3- imposing high frequency artificial vibration within a lattice leads to variation in the rate of tunelling.

In these cases the possibilty that spacetime suction exists could be boosted and may give a clue about quantum tunelling and halflives.

My last question is to some extent unrelated to the thread topic, but since +peaks may exist in spacetime curvature and fusion may take place, would it be possible to have cold fusion in this case? :confused:

Tensor
2012-Jun-17, 06:15 PM
Tensor, cjameshuff
As far as I can remember from college physics text books, all atoms in a lattice vibrate.

As far as you can remember? You mean you haven't even bothered to research if there has been any progress in this before making claims? Can you show how this works, in a lattice, AS CURRENTLY EXPLAINED, with second quantization?


Vibration is thought to be related to temperature, and collision of atoms is related to pressure and stress within lattice(similar to a gas under pressure at a temp above zero kelvin).

Yeah, and how does the creation of phonons through second quantization affect your contention here?


Now if there would be suction of spacetime within the lattice which might be the main cause of temp. and press.

Yeah, you still haven't shown suction of spacetime. Just some claims, which haven't been shown to make any kind of numerical predictions. And besides, as far as I can tell, it isn't a mainstream concept anyway.


then this spacetime may vibrate and have +peak and -peak within the lattice.

Can you explain why you need spacetime to vibrate, when lattice waves, along with phonons, describe by quantum processes, describes the process quite well? Not to mention, these descriptions have the mathematics to back them up. Your math is, where?


If vibration of individual atoms would be random,

If? You mean you haven't bothered to look into current thought on the matter?


then at particular parts of the lattice these peaks may cause peak -curvature and +curvature. These peak +ve or ve- curvatures may provide the ability for quantum tunelling or fusion .

Exactly how would this work, mathematically? How does this differ, mathematically, from quantum tunneling as described by Quantum Field Theory. How does Fusion differ here, from Quantum Field Theory?


For this reason I think inside BH, could exist very heavy elements as well.

By all means, show us how the interior of a black hole is similar to a lattice. How and where are the quantum processes operable within the black hole? And how, mathematically, this would lead to heavy elements.


It may give a clue if:
1- at zero kelvin, the rate of disintegration may reduce since atoms vibrate less(perhaps zero vibration). Surely experimental results exist to show what happens.

2- at zero kelvin it could be possible to vibrate the lattice in phase and create atomic resonance(I already have said a few words about this in my previous threads)?

3- imposing high frequency artificial vibration within a lattice leads to variation in the rate of tunelling.

In these cases the possibilty that spacetime suction exists could be boosted and may give a clue about quantum tunelling and halflives.

My last question is to some extent unrelated to the thread topic, but since +peaks may exist in spacetime curvature and fusion may take place, would it be possible to have cold fusion in this case? :confused:

None of the clues are anything more than extreme speculations that have no basis in experiment, in any kind of cognizant theory. Show us the experiments, the mathematical and theoretical background of your proposal, and how the math and theory match the experiment. Otherwise it's just more nonsense.

pzkpfw
2012-Jun-17, 07:20 PM
... Otherwise it's just more nonsense.

Yes. Thread closed. Once again ATM specualtion has been dressed up as questions by the OP.