Gravity question

[rjain]

Originally posted by: Sahakiel
The fact of the matter is, gravity WILL use a graviton at one point or another simply because it's the easiest concept for the human brain to process.

Well, the concept of a quantum mechanical "wavicle" isn't exactly easy for the human brain that's only been exposed to things that are easily observable with the natural human senses.
It is, however, much easier to understand for a physicist dealing with a quantized field. If the field doesn't turn out to be quantized, it won't make much sense to use a "graviton" to describe it. That said, I'd be rather surprised if there is no quantization involved. Due to the connection between gravity and coherence and the expectation that coherence will occur at deterministic points (but maybe not with deterministic results), I'd be surprised if there is no graviton.

 

[bwanaaa]

 

[bwanaaa]

CLARIFICATION of the supernova experiment

To measure the speed of gravity.

Imagine a very big star close to supernova. Look at the sky around it. Find a star farther away whose light passes close to the big star about to explode. This 'farther' star's light is being bent by the gravity of the big star about to explode. When the supernova occurs, the bending will cease and the position of the farther star's light will change. Keep an eye on both stars when supernova occurs. If gravity is instantaneous, then the position of the farther star will change at the same time you see the supernova. If gravity goes at the speed of light, you'll see the supernova first, then the position of the farther star will change. The time delay will tell you the speed of gravity if you know all the distances at the time of the event.

Has this experiment been done? Can it be done?

Stefan

 

[rjain]

It would probably take a few dozen years for a single trial of that experiment to be done, unless, of course, we were to be witness to a nearby supernova... Also, you'd need to predict when and where the supernova would occur and have a star that is aligned so that we get enough distortion of the farther star by the nearer star.
Actually... the light from the supernova and the light that is newly distorted would arrive here at the same time. The distance between the light's nearest approach to the nearer star is what we'd be basing the measurement on. I don't see how we can measure an effect of that time difference.

 

[bwanaaa]

If the farther star's light comes as close as 1 light week to the supernova and the supernova is 2 light years away, then gravity effect (1 light week / 104 light weeks=2 light yrs) is about 1% maximum possible difference. In other words, if gravity travels at the speed of light, the supernova appears 1 week before the farther star's apparent position changes. If gravity is instantaneous, both events are concurrent. If gravity is slower than the speed of light, the events occur at greater than a week apart.

Knowing when a supernova will occur I thought is something we could predict. Dont we know that by looking at the star's emissions?

Stefan

 

[rjain]

Originally posted by: bwanaaa
If the farther star's light comes as close as 1 light week to the supernova and the supernova is 2 light years away, then gravity effect (1 light week / 104 light weeks=2 light yrs) is about 1% maximum possible difference. In other words, if gravity travels at the speed of light, the supernova appears 1 week before the farther star's apparent position changes. If gravity is instantaneous, both events are concurrent. If gravity is slower than the speed of light, the events occur at greater than a week apart.

Ok, but I don't know how strong the field will be at 1 light week away for a star that typically is on the verge of supernova.

Knowing when a supernova will occur I thought is something we could predict. Dont we know that by looking at the star's emissions?

I don't know. Seems plausible, I guess.

 

[bwanaaa]

Well, how close to a massive object must a light path be to manifest the space distortion that Einstein predicted? What is the precision of current measurement technology? In other words, i know the experiment has already been done. Does anyone know the particulars?

 

[sao123]

The first problem is that, I dont know if your experiment is even valid.

I dont think that black hole formation can be characterized as instantanious. The stars explosion is instanious at that. But the explosion of the star with jetting material does not instantly become a black hole. There must be a cooling period where the re-vitalized fusion must slow and die. Then as the star begins to cool and solidify, then and only then can the collapse begin. Once again black hole formation is only theory, but this collapse takes time.

Here's the problem, Without an example of "severe nonlocalized instantanious gravitational disruption" being able to be generated. The graph of delta gravity with respect to time is still continuous over the interval T. It may change at a slope, and even a steep slope. But without a broken point in the graph, the speed of gravity is still an irrelevent question.

 

[rjain]

a change is a change. if it's significant enough to be detected, the delay can be observed.

 

[KRandor]

Originally posted by: Sahakiel

Masses by themselves do not transfer energy willy-nilly. Law of inertia. If it's moving, it's moving, if it's still, it's still. Either way, it's not using energy until it's accelerating. Classical mechanics.
Objects cannot create something from nothing. Law of conservation. If your "object which does not have ANY area ('space') within it" decides to draw energy from itself, it must, at one point or another, return the same amount of energy to where it was drawn.
Just reading that gives me the impression that you're assuming gravity is an energy transfer from one object to another. We cannot have a discussion of that idea if you keep referring to it as a law.

Noooo - O.k. so a lot of this was my fault for not explaining myself properly - (sorry!). Right then... What I really meant to say about mass and energy usage etc. is that the forms of energy it will be made up of at EVERY level - will be in CONSTANT motion - (in fact I expect that to be the case for the entire universe). The fact that gravity is a system of CONSTANT ACCELERATION means that an object HAS to be using energy constantly, no matter which direction gravity is travelling in... Like I also said, gravity will be part of an energy transfer CYCLE - whichever direction it is working in - there will be a corresponding amount of energy (in whatever form(s)) travelling in the opposite direction. The problem there, is that they will probably be as efficient as gravity, and if they do NOT affect anything that we can detect (unlike gravity) then it/they will be hard to discover... The 'fact' is that an object is obviously using energy - I just put a theory of HOW, forward - if you don't like it, then invent one of your own...;-) and P.S. it's obvious that gravity does not need 'two' objects in order to work - it only needs one, and dosen't have to operate 'between' two objects - it's just that that is the only way we know that it exists... (I.e. it affects the entire surrounding area of an object, whether there is another object there to act upon or not...).

The 'event horizon' is defined as r = G * M * c^-2 and can be calculated for any object with mass and volume. It is basically the size to which an object must shrink down to in order to become a 'black hole.'
Gravity cannot "exceed c," as you like to say.

Actually, for 'black holes' to exist then gravity MUST be able to travel faster than c... SInce that is what causes the black hole in the first place... Oh and don't try and put like this book did - (I think it was A Brief History Of Time - Dr Steven Hawking) - where gravity works fine until it reaches c - then look, it magically stops accelerating for the rest of the way 'down'...:-/ If gavity accelerates stuff then it will do it ALL the way down, just like all the evidence suggests, and since it's more efficient (and works at a much lower level) than light - (even physicists agree with me on THAT one) - there should be no reason WHY it couldn't possibly travel faster... It's simple - if black holes exist, then gravity CAN exceed c - and if they don't then we don't know if it can or can't...

If the mass is equal, then how can the total field strength be different? It's like comparing a bucket of electrons to a cup with the same number of electrons and saying the smaller cup has more charge because it is smaller even though it has the same number of charged particles.

I think we're getting some wires crossed around here somewhere....:-/ Like I said, the overall amount of energy used by objects of equal mass / transferred by their gravitational fields WILL BE EQUAL. (E=E). The problem here, (for you), is that gravity is a force, which accelerates everything we know of in an area surrounding an object. What I am saying is that if the amount of AREA over which the force operates is different then it's RATE OF ACCELERATION WILL BE DIFFERENT in direct proportion in order for the total amount of energy transferred to be the same... And since the strength of gravity is defined by it's rate of acceleration, then the field STRENGTH will therefore be different...

If mass uses energy then explain to me why energy is defined in terms of mass and not the other way around.
This is the crux of my difficulty in understanding your logic. It seems to me you're introducing a theory contrary to a couple hundred years' worth of work. If you're able to do that successfully, I would suggest hopping on the next plane to Norway instead of wasting your time on the forums.

Energy and work defined in the classical sense relate only to matter. We're talking about mass, which is different.

The definition of energy I have been using does not mention the word 'matter' (or 'mass') at all... (And neither did 'work' for that 'matter'). In fact as we 'burrow' deeper into the working of the universe, I expect the term 'energy' to still be used, since it does still work... Energy and work are a couple of terms which CAN be used universally due to their definitions, and in fact it may not be such a bad thing...

The only way to supply energy with one thing ( say, x-rays in your microwave) is to merge with something else (your food). There are no magical fields emanating from objects which influence other objects without the benefit of a
Law of Conservation.

Who said anything about gravity supplying energy via gravity? Last I checked, the classical equations on which you're probably basing your ideas do not "transfer energy" within objects; only "convert energy." For example, from kinetic to potential and back. Transfer of energy between objects has always involved seperating a part of the object from the source object which becomes a messenger particle which then merges with the destination object, thus completing the energy transfer.

If gravitons are 'emitted' (as per current 'thought') - then energy has to be being transferred away from an object... Unfortunately, if that were the case, then gravity would have to be fairly inefficient to have the effects we see (which is also why we have some of the current stuff like: The reason every object falls at the same speed is that they resist the movement in proportion to their mass - which if it were the case then the gravitational field beyond the object would also be affected (i.e. some energy would be absorbed by the object and not transferred onto whatever's above it) (and it's not affected) - (consistency in direction and rate, remember)) - which is something that it is not - (and like I said even physicists admit that gravity is VERY efficient). The problem with gravity and the 'messenger particle' stuff is that at the level it works at, particles probably don't exist as such, and it's not just working btween 'objects' - it's obviously working on things we have no knowledge of atm...

Efficiency is defined as the work output over the work input. Using it to determine detection is akin to using a sine wave in digital electronics. It works, but probably not in the way it's designed. Other than that, detection and how it affects objects is the realm of quantum mechanics, which is truthfully out of my league.

I know that me calling 'consistency in direction and rate of transfer' Efficiency wasn't really in line with it's current definition, but I didn't know what else to call it...:-/ If you have any suggestions, please let me know...

What I do know is that yes, particles will only take us so far. That's why waves are used. That photon you're so fond of pointing out can be represented as a wave in different situations. It's called particle/wave duality, and every speck of matter you see before you has this property as well as every speck of light.
Why will gravity not use a graviton? This problem was once considered with light. The fact of the matter is, gravity WILL use a graviton at one point or another simply because it's the easiest concept for the human brain to process.

The reason why gravity should not use a 'graviton' is that it has NO properties that can be associated with a particle AT ALL - It works at too low a level for that... - (Unlike EM radiation/matter etc...). Using 'waves' on the other hand should work... (I think).

 

[Mingon]

On a side note a UK science magazine 'focus' has an article on gravitational waves and a test site in italy, I can scan it for anyone interested just PM me. the virgo project

 

[Sahakiel]

Originally posted by: KRandor
Noooo - O.k. so a lot of this was my fault for not explaining myself properly - (sorry!). Right then... What I really meant to say about mass and energy usage etc. is that the forms of energy it will be made up of at EVERY level - will be in CONSTANT motion - (in fact I expect that to be the case for the entire universe). The fact that gravity is a system of CONSTANT ACCELERATION means that an object HAS to be using energy constantly, no matter which direction gravity is travelling in...

Constant acceleration is a classical explanation. It is the same as with electrons orbiting atomic nuclei. For the longest time, people wondered why electrons do not eventually spiral and crash into the nucleus of the atom. This is where General Relativity broke down and Quantum Mechanics took over.
Now, the question becomes, what is the difference between a planet orbiting a sun as opposed to an imbalanced baton twirling in a vacuum? Answer that with your theory.
(and no, I do not mean state the obvious. Explain the behavior)

Like I also said, gravity will be part of an energy transfer CYCLE - whichever direction it is working in - there will be a corresponding amount of energy (in whatever form(s)) travelling in the opposite direction. The problem there, is that they will probably be as efficient as gravity, and if they do NOT affect anything that we can detect (unlike gravity) then it/they will be hard to discover... The 'fact' is that an object is obviously using energy - I just put a theory of HOW, forward - if you don't like it, then invent one of your own...;-)

I have no need to. Others with greater intelligences than ours have done the work for me. An object doesn't 'use' energy; It is energy.
What you are proposing is anti-gravity, which is also under speculation. Also, if it does not affect anything that we can detect (like gravity) then it cannot be part of this "transfer cycle" because it would not affect any point of the transfer cycle in the first place. This would mean it is not part of the transfer cycle. If anything affects anything else, it can be detected. If there exists something which cannot be detected, then it does not exist. (see below)

and P.S. it's obvious that gravity does not need 'two' objects in order to work - it only needs one, and dosen't have to operate 'between' two objects - it's just that that is the only way we know that it exists... (I.e. it affects the entire surrounding area of an object, whether there is another object there to act upon or not...).

Incorrect. Gravity requires two objects to work. It's like saying a light bulb will illuminate a room whether or not anyone is there to see it. Reference Schroedinger's cat or Heisenberg's Uncertainty Principle if you're lost.

Actually, for 'black holes' to exist then gravity MUST be able to travel faster than c... SInce that is what causes the black hole in the first place...

I thought we already agreed that 'black holes' are formed when an object is constricted to a size smaller than its <FONT size=1>Shwarzchild radius. That statement is independent of the speed of gravity or anything else, for that matter.</FONT>

Oh and don't try and put like this book did - (I think it was A Brief History Of Time - Dr Steven Hawking) - where gravity works fine until it reaches c - then look, it magically stops accelerating for the rest of the way 'down'...:-/ If gavity accelerates stuff then it will do it ALL the way down, just like all the evidence suggests, and since it's more efficient (and works at a much lower level) than light - (even physicists agree with me on THAT one) - there should be no reason WHY it couldn't possibly travel faster... It's simple - if black holes exist, then gravity CAN exceed c - and if they don't then we don't know if it can or can't...

I'm assuming you're saying that gravity is strong enough to prevent light from escaping the event horizon. That, in and by itself, is not sufficient evidence to support the idea that gravity propogates faster than light. If such a simple phenomenon were capable of providing enough basis to support it, we wouldn't be here arguing over it in the first place.

I think we're getting some wires crossed around here somewhere....:-/ Like I said, the overall amount of energy used by objects of equal mass / transferred by their gravitational fields WILL BE EQUAL. (E=E). The problem here, (for you), is that gravity is a force, which accelerates everything we know of in an area surrounding an object. What I am saying is that if the amount of AREA over which the force operates is different then it's RATE OF ACCELERATION WILL BE DIFFERENT in direct proportion in order for the total amount of energy transferred to be the same... And since the strength of gravity is defined by it's rate of acceleration, then the field STRENGTH will therefore be different...

Two things.
1. I'm not having any problem in dealing with gravity as a force. It's much simpler at my limited knowledge level to contemplate with classical concepts.
2. Your idea is this : The reason why gravity is directly proportional to the inverse square of the distance away from the source is similar to electrical fields : the total field strength, if measured with any type of enclosure around the source, is constant.
I haven't argued against that. In fact, I've been trying to argue that this is how things are. From what I am reading, you're the one having a problem accepting that the total field strength is constant.

The definition of energy I have been using does not mention the word 'matter' (or 'mass') at all... (And neither did 'work' for that 'matter'). In fact as we 'burrow' deeper into the working of the universe, I expect the term 'energy' to still be used, since it does still work... Energy and work are a couple of terms which CAN be used universally due to their definitions, and in fact it may not be such a bad thing...

Any word in the English language can be used universally. In fact, any word in any language can be used universally. Unfortunately, due to the limitations of language and the internet, it would be nice to use the dictionary definition as opposed to reassigning words to random concepts; it's not helping your case.
If you're referring to the use of energy to define the universe, then this is nothing new. The concept of forces has met a similar demise, being now relegated to introductary level physics. Energy is, as far as I know, the more widely used basis for mid-level physics and beyond.

If gravitons are 'emitted' (as per current 'thought')

Actually, no, current "thought" would probably be closer to a field or a bend in spacetime, depending on who you ask. Gravitons are currently considered flights of fancy.

- then energy has to be being transferred away from an object... Unfortunately, if that were the case, then gravity would have to be fairly inefficient to have the effects we see

And here I was, thinking you were trying to say that gravity is very "efficient." If what we see (and that includes black holes) requires it to be "fairly inefficient"...

(which is also why we have some of the current stuff like: The reason every object falls at the same speed is that they resist the movement in proportion to their mass - which if it were the case then the gravitational field beyond the object would also be affected (i.e. some energy would be absorbed by the object and not transferred onto whatever's above it) (and it's not affected) - (consistency in direction and rate, remember)) - which is something that it is not - (and like I said even physicists admit that gravity is VERY efficient).

Yet, the gravitational field beyond the object is affected. One has merely to view the stars in the sky as an object passes close. That type of activity was used to verify Special Relativity and is routinely used to detect black holes (which are technically thereotical).

The problem with gravity and the 'messenger particle' stuff is that at the level it works at, particles probably don't exist as such, and it's not just working btween 'objects' - it's obviously working on things we have no knowledge of atm...

Once again, what you do not know can't hurt you. Similar idea in that what you have no knowledge of cannot exist. Once it is detected, it is known, and therefore, exists. Reference above if you're confused.

I know that me calling 'consistency in direction and rate of transfer' Efficiency wasn't really in line with it's current definition, but I didn't know what else to call it...:-/ If you have any suggestions, please let me know...

Try 'inertia', as defined in Newtonian Physics. And it really has almost nothing to do with why the use of gravitons is inappropriate for any model.

The reason why gravity should not use a 'graviton' is that it has NO properties that can be associated with a particle AT ALL - It works at too low a level for that... - (Unlike EM radiation/matter etc...). Using 'waves' on the other hand should work... (I think).

Try strings.
There does seem to be a growing number who believe in string theory, which is probably more along the lines of a fledgling Theory than a flight of fancy.
Oh, wait, unfortunately, string theory allows for the existence of gravitons.

Let me ask you this :
How do you measure space?
Answer: With a ruler.
Now ask, what happens if the ruler changes shape?

Once you've answered that, think about what happens if gravity actually propogates in the same manner as light.
It's an interesting exercise, although derived from nothing more then idle thought.

 

[KRandor]

Originally posted by: Sahakiel
Constant acceleration is a classical explanation. (SNIP!)

Dear me... Is gravity a CONSTANT FORCE (or not)?... If it is, then it must provide constant acceleration (which it does)...lol. Trying to make things more complicated than they need to be won't get you very far...:-/

I have no need to. Others with greater intelligences than ours have done the work for me. An object doesn't 'use' energy; It is energy.
What you are proposing is anti-gravity, which is also under speculation. Also, if it does not affect anything that we can detect (like gravity) then it cannot be part of this "transfer cycle" because it would not affect any point of the transfer cycle in the first place. This would mean it is not part of the transfer cycle. If anything affects anything else, it can be detected. If there exists something which cannot be detected, then it does not exist. (see below).

Excuse me, but the entire universe is 'working' - i.e. using energy, (which is what working means) - lol - as will objects... (P.s. I meant 'detect at this time' - sorry).

Incorrect. Gravity requires two objects to work. It's like saying a light bulb will illuminate a room whether or not anyone is there to see it. Reference Schroedinger's cat or Heisenberg's Uncertainty Principle if you're lost.

Gravity does NOT need two objects to 'work' - it only needs two objects FOR US TO 'SEE' IT WORKING - <I>BIG</I> DIFFERENCE. Look, the whole point about science is to find out the general rules by which the universe works, and ditching those rules because 'we're not sure so we'll discount them', even if they account for what we 'know' kills the reason for finding the rules out in the first place, lol - (Only saying that much because of an article I read in New Scientist once that went WAAAY too far, lol)... And I don't agree with Schrodinger's cat - it can only be alive OR dead - not both, since that goes against what we know is possible - just because we don't know if it is alive or dead dosen't mean it can be both (Anyone seen a zombie cat around here lately? ;-) )... The problem is not with the cat (or the universe, etc.) but with our understanding and perception of it. The problem is that people have gone too far and are assuming that the universe is affected by us NOT viewing it, which of course IT WON'T BE... It's only in certain situations that in trying to find out something we have to alter the result when we do so, which is a different situation altogether - (Heisenberg's Uncertainty Principle). Yes, if we don't know what is happening - (i.e. the speed/direction of a particle) - then it could 'technically' be anything - BUT - it should be possible to make estimations based on other information/knowledge/rules we already have. To throw all those out of the water, and to assume things which haven't been proven seen etc. (even though there may be other information to suggest/estimate the result anyway) simply destroys the reason for finding out the rules in the first place... (Unfortuantely there seem to ba a lot of people that have taken everything too far, though hopefully they'll get reigned back in as our understanding increases).

I thought we already agreed that 'black holes' are formed when an object is constricted to a size smaller than its <FONT size=1>Shwarzchild radius. That statement is independent of the speed of gravity or anything else, for that matter.</FONT>

Yes, but why is it called a 'Black Hole' in the first place? Because the gravitational field is stronger than - (i.e. it's accelerated beyond) - the speed of light, so light can't 'escape'. Like I said, the distance between the object, and the point at which light cannot escape, will tell us exactly how fast gravity can accelerate things to - because gravity won't stop accelerating, even if the distance between these to points can be measured in km... Of course, if there IS no distance between the two, then things would be different (and more in line with what you are saying), but we don't know enough to make any real statements on this yet

I'm assuming you're saying that gravity is strong enough to prevent light from escaping the event horizon. That, in and by itself, is not sufficient evidence to support the idea that gravity propogates faster than light. If such a simple phenomenon were capable of providing enough basis to support it, we wouldn't be here arguing over it in the first place.

If the event horizon is the same size as the object in question, then there will be no problem - but if it's bigger, then gravity must be able to travel faster... (Simpler way of repeating what I said above).

Two things.
1. I'm not having any problem in dealing with gravity as a force. It's much simpler at my limited knowledge level to contemplate with classical concepts.
2. Your idea is this : The reason why gravity is directly proportional to the inverse square of the distance away from the source is similar to electrical fields : the total field strength, if measured with any type of enclosure around the source, is constant.
I haven't argued against that. In fact, I've been trying to argue that this is how things are. From what I am reading, you're the one having a problem accepting that the total field strength is constant.

O.k. - start again - please define what you mean by 'Total field strength' as far as gravity is concerned... (I have to define it as the velocity of it's field at a certain distance). For most objects this might be consistent, but not for 'black holes' if what I am describing is correct...

Any word in the English language can be used universally. In fact, any word in any language can be used universally. Unfortunately, due to the limitations of language and the internet, it would be nice to use the dictionary definition as opposed to reassigning words to random concepts; it's not helping your case.
If you're referring to the use of energy to define the universe, then this is nothing new. The concept of forces has met a similar demise, being now relegated to introductary level physics. Energy is, as far as I know, the more widely used basis for mid-level physics and beyond.

That's because above that level, the forms of energy and rules by which they operate are paramount... So dealing with 'energy' on it's own isn't really feasible - (and will make things even more complicated than they already are).

Actually, no, current "thought" would probably be closer to a field or a bend in spacetime, depending on who you ask. Gravitons are currently considered flights of fancy.

Guess I was out-of-date there then, oh well - doesen't matter...

then energy has to be being transferred away from an object... Unfortunately, if that were the case, then gravity would have to be fairly inefficient to have the
And here I was, thinking you were trying to say that gravity is very "efficient." If what we see (and that includes black holes) requires it to be "fairly inefficient"...

(I was only following on, lol - just ignore all that, and I'll ignore the reply).

Yet, the gravitational field beyond the object is affected. One has merely to view the stars in the sky as an object passes close. That type of activity was used to verify Special Relativity and is routinely used to detect black holes (which are technically thereotical).

You're right - it IS affected, (by it's own gravitational field), but not by anything else... (which it would have been otherwise) - but anyway...

Once again, what you do not know can't hurt you. Similar idea in that what you have no knowledge of cannot exist. Once it is detected, it is known, and therefore, exists. Reference above if you're confused.

Disagree with the first statement - (through experience, lol).

Try 'inertia', as defined in Newtonian Physics.

Nope, sorry, inertia doesen't work...:-/

Try strings.
There does seem to be a growing number who believe in string theory, which is probably more along the lines of a fledgling Theory than a flight of fancy.
Oh, wait, unfortunately, string theory allows for the existence of gravitons.

I've had a look at string theory before... (Am waiting to see what happens before making any judgements, though I still think we're trying to glue things together at the wrong levels...).

Let me ask you this :
How do you measure space?
Answer: With a ruler.
Now ask, what happens if the ruler changes shape?

Make one which doesen't suffer from that problem - i.e. is made relative to the person using it rather than the space it occupies - otherwise, yes, there will be a problem trying to use a ruler which is measuring space in a different 'frame of reference' than you...

Once you've answered that, think about what happens if gravity actually propogates in the same manner as light.
It's an interesting exercise, although derived from nothing more then idle thought.

The problem comparing gravity and light, is that they are both efficient - (though in different ways - i.e. one constantly decelerates, the other does not) - when travelling through space, but unlike gravity, light affects/is affected by other objects inefficiently... Gravity, however, does/is not...

 

[glugglug]

Originally posted by: KRandor


Dear me... Is gravity a CONSTANT FORCE (or not)?... If it is, then it must provide constant acceleration (which it does)...lol. Trying to make things more complicated than they need to be won't get you very far...:-/

No, it's not. Gravitational accleration varies inversely with the square of distance between 2 masses.

I thought we already agreed that 'black holes' are formed when an object is constricted to a size smaller than its <FONT size=1>Shwarzchild radius. That statement is independent of the speed of gravity or anything else, for that matter.</FONT>

Actually a black hole is formed when one of 2 things happen:
a) enough mass is clumped together in one region of space that the gravitational pull is greater than that required to keep light in orbit. Specifically, the mass within a spherical region of space with radius R exeeds c^2 * R/G.

b) Some matter is accelerated to the point that its relativistic mass exceeds the above formula for the radius containing it. This is how microscopic black holes are currently being artificially created using subatomic particles accelerated to near the speed of light. In order to keep the black hole in one spot (relative to Earth) so that it can be more "useful", these particles would have to be orbiting each other really fast to have that relativistic mass instead of moving in a straight line.

O.k. - start again - please define what you mean by 'Total field strength' as far as gravity is concerned... (I have to define it as the velocity of it's field at a certain distance). For most objects this might be consistent, but not for 'black holes' if what I am describing is correct...

Acceleration the field causes at a given point in space, multiplied by the surface area of the sphere that cuts through that point centered at the source of the field would be the "Total field strength", which being constant kind of lends to the idea of gravity having a propagation delay.

Actually, no, current "thought" would probably be closer to a field or a bend in spacetime, depending on who you ask. Gravitons are currently considered flights of fancy.

Guess I was out-of-date there then, oh well - doesen't matter...

The field is certainly the easier concept to grasp. The spacetime bending makes my head spin trying to think about it, although it is probably more accurate.

Yet, the gravitational field beyond the object is affected. One has merely to view the stars in the sky as an object passes close. That type of activity was used to verify Special Relativity and is routinely used to detect black holes (which are technically thereotical).

You're right - it IS affected, (by it's own gravitational field), but not by anything else... (which it would have been otherwise) - but anyway...

???? --- what are you saying here?

 

[Sahakiel]

Originally posted by: KRandor
Dear me... Is gravity a CONSTANT FORCE (or not)?... If it is, then it must provide constant acceleration (which it does)...lol. Trying to make things more complicated than they need to be won't get you very far...:-/

When I said it's a classical explanation, I meant that it's much closer to ideal than current theory. Classical mechanics is the much simpler, more intuitive, version of physics taught in junior high and high school and provides the basis for building General Relativity, Quantum Mechanics, High Energy physics, etc, etc. Classical mechanics ignores special cases, being confined to the environment in which we live.

Excuse me, but the entire universe is 'working' - i.e. using energy, (which is what working means) - lol - as will objects... (P.s. I meant 'detect at this time' - sorry).

"Work" is defined in Newtonian Physics as a force applied to an object which causes the object to move. If the object does not move, there is no "work" done. If the object does not experience a force, then there is no "work" possible. If you wish to discuss physics, use the terms correctly (or as well as your understanding of physics allows).

Gravity does NOT need two objects to 'work' - it only needs two objects FOR US TO 'SEE' IT WORKING - <I>BIG</I> DIFFERENCE.

The problem is that having us or anything else 'see' it working is the only way it 'works.'

Look, the whole point about science is to find out the general rules by which the universe works, and ditching those rules because 'we're not sure so we'll discount them', even if they account for what we 'know' kills the reason for finding the rules out in the first place, lol - (Only saying that much because of an article I read in New Scientist once that went WAAAY too far, lol)...

Ditching those rules is exactly what you're doing, by the way. It's also how one first learns physics: ditch the complicated rules, set up ideal situations to explain phenomena, then experiment and discount errors as just that. Once you get a good grasp of the basics, then and only then do you introduce the rules which were discarded earlier.

And I don't agree with Schrodinger's cat - it can only be alive OR dead - not both, since that goes against what we know is possible - just because we don't know if it is alive or dead dosen't mean it can be both (Anyone seen a zombie cat around here lately? ;-) )... The problem is not with the cat (or the universe, etc.) but with our understanding and perception of it. The problem is that people have gone too far and are assuming that the universe is affected by us NOT viewing it, which of course IT WON'T BE... It's only in certain situations that in trying to find out something we have to alter the result when we do so, which is a different situation altogether - (Heisenberg's Uncertainty Principle). Yes, if we don't know what is happening - (i.e. the speed/direction of a particle) - then it could 'technically' be anything - BUT - it should be possible to make estimations based on other information/knowledge/rules we already have. To throw all those out of the water, and to assume things which haven't been proven seen etc. (even though there may be other information to suggest/estimate the result anyway) simply destroys the reason for finding out the rules in the first place... (Unfortuantely there seem to ba a lot of people that have taken everything too far, though hopefully they'll get reigned back in as our understanding increases).

Congratulations, you have just thrown out 80 years of work in physics, destroyed electron microscopes, and neutralized electron tunneling in microprocessor design some five years from now.
And that's just the short list.


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Originally posted by: <FONT face=Verdana>glugglug</FONT>b) Some matter is accelerated to the point that its <I>relativistic mass</I> exceeds the above formula for the radius containing it. This is how microscopic black holes are currently being artificially created using subatomic particles accelerated to near the speed of light. In order to keep the black hole in one spot (relative to Earth) so that it can be more "useful", these particles would have to be orbiting each other really fast to have that relativistic mass instead of moving in a straight line</FONT>

That I did not know. I'd always wondered how one would create an artificial black hole..

Yes, but why is it called a 'Black Hole' in the first place? Because the gravitational field is stronger than - (i.e. it's accelerated beyond) - the speed of light, so light can't 'escape'. Like I said, the distance between the object, and the point at which light cannot escape, will tell us exactly how fast gravity can accelerate things to - because gravity won't stop accelerating, even if the distance between these to points can be measured in km... Of course, if there IS no distance between the two, then things would be different (and more in line with what you are saying), but we don't know enough to make any real statements on this yet

Now gravity can accelerate? How interesting...
However, I think you forget that gravity is not running a drag race with the light it absorbs. If you fired a laser alongside a black hole, the laser bends towards the black hole. If it's close enough, it'll enter the event horizon. Light from the other side of the black hole does the same thing.
The light doesn't have to 'outrun' gravity. It just has to 'run into' gravity.

If the event horizon is the same size as the object in question, then there will be no problem - but if it's bigger, then gravity must be able to travel faster... (Simpler way of repeating what I said above).

(see above)

O.k. - start again - please define what you mean by 'Total field strength' as far as gravity is concerned... (I have to define it as the velocity of it's field at a certain distance). For most objects this might be consistent, but not for 'black holes' if what I am describing is correct...

<FONT size=1>Here:

Originally posted by: <FONT face=Verdana>glugglug</FONT>Acceleration the field causes at a given point in space, multiplied by the surface area of the sphere that cuts through that point centered at the source of the field would be the "Total field strength", which being constant kind of lends to the idea of gravity having a propagation delay.

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That's because above that level, the forms of energy and rules by which they operate are paramount... So dealing with 'energy' on it's own isn't really feasible - (and will make things even more complicated than they already are).

Almost sounds like you're discounting your own ideas.
The reason is actually because at that level, throwing out forces as the basis for every calculation leaves a more precise picture of the universe. It usually complicates matters because it's no longer guaranteed intuitive.

Once again, what you do not know can't hurt you. Similar idea in that what you have no knowledge of cannot exist. Once it is detected, it is known, and therefore, exists. Reference above if you're confused.

Disagree with the first statement - (through experience, lol).

Explanation :
You cannot know of something which you cannot detect. You can theorize all you want, but it's still confined in the realm of fantasy. However, once the object has affected an instrument (in this case, you) then it has been detected. Once it has been detected, then, and only then, can you postulate as to whether it's harmful or not. Therefore, what you do not know cannot hurt you.

I've had a look at string theory before... (Am waiting to see what happens before making any judgements, though I still think we're trying to glue things together at the wrong levels...).

In that case, you're welcome to join in and point out where they're wrong.

Make one which doesen't suffer from that problem - i.e. is made relative to the person using it rather than the space it occupies - otherwise, yes, there will be a problem trying to use a ruler which is measuring space in a different 'frame of reference' than you...

I think you missed the point. The question was asking, what happens when space itself becomes distorted?
The ruler, by definition, will be affected by that problem. Rulers take up space and rulers that measure space are, by defintion, measured relative to space, not relative to the observer. So the point is, how do you know the ruler is accurate?

Once you've answered that, think about what happens if gravity actually propogates in the same manner as light. It's an interesting exercise, although derived from nothing more then idle thought.

The problem comparing gravity and light, is that they are both efficient - (though in different ways - i.e. one constantly decelerates, the other does not) - when travelling through space, but unlike gravity, light affects/is affected by other objects inefficiently... Gravity, however, does/is not...

Once again, you missed the point.
Light travels in straight lines; true to the lines of spacetime.
Gravity has been theorized (and proven to an extent) to bend spacetime.
Now ponder the idea that gravity also travels along the lines of spacetime.
Makes my head ache, but still interesting, nonetheless.

P.S. I'm still having a hard time reading your posts. Could you find a better term than 'efficiency'? Using terms in their context helps immensely.

 

[rjain]

Actually, gravity "bending" spacetime is in contradiction with some observations. That whole interpretation is just because mathematicians like that construct more because it's more mathematically "perfect". However, nature doesn't conform to rules we make up. Also, it seems that gravity might have a weak interaction with itself.

 

[KRandor]

Originally posted by: glugglug

[No, it's not. Gravitational accleration varies inversely with the square of distance between 2 masses.

Yes it is - if you only have one mass - (what did I say about making things more complicated?) - try using an object of mass and other which doesen't - say light or something...

Actually a black hole is formed when one of 2 things happen:
a) enough mass is clumped together in one region of space that the gravitational pull is greater than that required to keep light in orbit. Specifically, the mass within a spherical region of space with radius R exeeds c^2 * R/G.

b) Some matter is accelerated to the point that its relativistic mass exceeds the above formula for the radius containing it. This is how microscopic black holes are currently being artificially created using subatomic particles accelerated to near the speed of light. In order to keep the black hole in one spot (relative to Earth) so that it can be more "useful", these particles would have to be orbiting each other really fast to have that relativistic mass instead of moving in a straight line.

I didn't know that an objects relativistic mass affected it's gravitational field... Do you have a link for that one? (Like to learn more...).

Acceleration the field causes at a given point in space, multiplied by the surface area of the sphere that cuts through that point centered at the source of the field would be the "Total field strength", which being constant kind of lends to the idea of gravity having a propagation delay.

O.k. - I can understand why that answer would be constant... (Dealing with acceleration rather than velocity - which CAN be different, which is the point I was trying to make - since we KNOW that the rate of acceleration caused by gravity is constant... It's velocity/distance however, will vary according to it's mass at least...)..

The field is certainly the easier concept to grasp. The spacetime bending makes my head spin trying to think about it, although it is probably more accurate.

Have you read what I (personally) have defined space and time as???

Right - starting from scratch (again...;-) ):


Energy: The capacity of a physical system to do work

Work: The transfer of energy from one physical system to another...


If we deal with the entire universe as a 'physical system' (which can also be split into other, smaller 'physical systems') - then:


Space: The volume within which the energy occupies and directions in which the energy is transferred...

Time: The rate at which the energy is transferred - (which we measure relative to the speed of light / rotation of the planet Earth etc...).


So - all we are saying is that gravity affects the direction(s) the energy is transferring in, and the rate at which it does so... - Big deal...;-/

???? --- what are you saying here?

What I said was that if gravity was inefficient, then it would be affected by other objects a lot more than at present - since at present we know that other gravitational fields affect each other, though if the objects affected it aswell, then it's consistency would be far less than what we see...