Science a GoGo's Home Page Forums General Discussion Physics Forum Open challenge

Since we have an abundance of alternate theory experts lets try and see if we can get some real conversation going. I want you to read the article by Ethan Siegel

https://medium.com/starts-with-a-bang/as...le-5ef156bf048d

It actually harks back to a discussion I was having with Bill G/Bill S when they were trying to use a rubber sheet and ball weights as a simulation of gravity and get them to see the problem. Lets just say they didn't get it or the implications but lets try the alternative theory guys.

The key point is that any valid theory is going to have to explain

1.) How does gravity get out of a black hole.

Background: Gravity interacts with itself and everything attracts everything else. So if you create a black hole that stops even light leaving how is it gravity itself is getting out?


2.) Why is the speed of gravity restricted to the speed of light

Background: Gravity has been measured a number of different ways and all put it's speed at between 0.8c to 1.2c and that is consistent with the most likely that it is in fact c (https://en.wikipedia.org/wiki/Speed_of_gravity)


3.) What is opposing the black hole so that the black hole gravity does not go to infinity (What limits the collapse).

Background: There has to be something opposing gravity otherwise whatever your theory the universe is going to collapse or at the very least start shrinking into every black hole. Worse still try and create the universe if gravity is not opposed.

I don't want crazy other details of your alternative theory but just deal exclusively with the 3 points asked.

I’ve not read the article yet, but here’s a quick shot at the questions.

“1.) How does gravity get out of a black hole?”

It doesn’t. Gravity is not a force, it is a feature of the geometry of spacetime. Spacetime is influenced by the presence of the mass of the black hole; not by anything that has to escape from it.

“2.) Why is the speed of gravity restricted to the speed of light?”

Gravity does not travel. What travels is information about the presence/nature of the mass in question. Exchange of information is limited to “c”.

“3.) What is opposing the black hole so that the black hole gravity does not go to infinity (What limits the collapse)?”

If the centre of a black hole is a singularity, this is defined as a point where spacetime curvature is infinite, so gravity is infinite. Obviously, spacetime could not become more curved, and the area of infinite curvature must be infinitesimally small, so it is self limiting.

Remember: I am not giving an answer and there is no right/wrong from me. I am simply looking at the logic of your responses and ultimately whether I can believe your theory.


So how does it interact with matter and know when to deform ... divine perception(god tells it)?

Being facetious but it highlights the problem there has to be an interaction which you refer to as influence.

Go back to your rubber sheet and ball example the deformation is created by the mass. The mass is opposed by the rubber tension of the runner stretching and that gives you the proportionality that a heavy mass deforms more than a light mass.

Now go back to the gravity example there is proportionality. You may care to think about what are the other possibilities besides proportional and why is proportional selected?

So what you deem as an influence must (a) come out of the black hole and (b) create a proportional response to mass/distance which we write as a formula.


If gravity does not travel how does it act at distance and how can we even do the experiments to measure its speed?

I sort of get the information bit as that is very QM but you lost me with how something that doesn't travel have a speed at all.

I am guessing you are going to equate "information" to energy along the lines of QM?


Think more carefully about what you have said gravity is going to reach infinity

So we are back to our problem why doesn't the universe get instantly sucked back into the infinite gravity, what stops it?

I guess I could say the universe is a positive infinity and try and balance it but even then I am seeing an issue. Supposedly how many black holes are there in the universe?

To me the logic ends up at one extra big infinity is offset by lots of small infinities ... not sure I like this sort of maths

The fact your value can drop to infinity still leaves me questioning proportionality, why doesn't a bit of matter create gravity that instantly drops to infinity? Why does it require a lot of matter to produce the infinity?

I have a much deeper more technical problem with your answer but lets first clear the simple ones.

I was trying to frame the argument in terms of what seems to be accepted scientific (hitch-hiker level) terminology, and at the same time stay off my usual “hobby-horse” about infinity.



I’m glad you don’t like it. If it makes any sense at all, it is only in terms of mathematical infinities, which are simply bookkeeping conveniences.

Let’s try to dispense with infinities, at least for the time. A black hole exists in time; it has a beginning and, as far as we know, an end. It is finite. Nothing finite can become infinite, so the most we can say about the centre of a black hole is that its curvature is able to increase “infinitely”. This brings us back to the distinction between infinite and boundless.

In the interests of taking one step at a time, can we agree on what we mean when we talk of something becoming infinite? Would this be the same as what we mean if we say that something goes to infinity?

My response to those questions would be that the first is meaningless, and the second refers to boundlessness.

Realistically I don't get hung up on infinity like you seem too, it is a description of a behaviour to me nothing more or less.

My issue is gravity increases to some incredible value and there are 2 obvious issues

1.) What controls the rate of drop off to whatever you want to call that bottom value ... infinity/bound?

This is the issue of proportionality ... here is a plot of Earths gravity well.


Now that is a steep drop why doesn't it keep plummetting to the infinity/bound condition?

GR has an explaination for the rate of dropoff and even why the value doesn't go to infinity/bounds and so any competing theory needs to do the same.


2.) What is the nature of the interaction between matter and gravity?

Ideally an alternative theory would be able to shed light on this although for its part GR does not describe what causes the interaction. GR merely places a curvature relationship in time on all space coordinates radiating out to infinity/universe bounds by some unknown process.

Pushed for time at the moment, but coming back. Thought I should say I have no objection to using "infinity" in this way; just as long as we all understand how we are using it.

Looking at your diagram (let’s call it Fig. 1 in case there are more) it is easy to imagine that something needs to act on the Earth to stop it falling further down that well, possibly to infinity. Remember, though, that this is just a small fraction of a 2D model of the real thing. To be a complete 2D illustration there would have to be an infinite number of gravity wells surrounding the Earth. Even without attempting the impossible, you could draw enough gravity wells around the Earth to get rid of that apparent, but totally wrong, view that something – gravity? – is pulling the Earth “downward” in Fig.1.

Gravity is, if it is to be thought of in terms of gravity wells, an infinite number of wells, radiating in 3D from the Earth.

There is no downward direction, except towards the Earth, at the centre of this infinite number of gravity wells.

Why would this be seen as a situation in which any force is trying to move the Earth in any direction from its apparently stable position at the centre of this setup?

If there is such a force, would it not be balanced by an equal force acting on the Earth from an infinite number of directions?

You might need to be more specific in what you are asking here. There could, for example, be a Q/A sequence that went something like this:

Q. What is the nature of the interaction between matter and gravity?
A. Mass distorts spacetime which results in what we interpret as gravity.

Q. How does mass achieve this?
A. Simply by being there.

Q. Why does this work?
A. “Why” questions take us outside science, and into philosophy.

Ummmm ... so again exactly what is curving and how are you measuring it?

You are going to have to do that one from the top for me, I am missing something

So lets extend your Q & A session

Orac) How does mass achieve this?
Bill.S) Simply by being there.
Orac) So you have a correlation but no causation?


Orac) Why does this work?
Bill.S) “Why” questions take us outside science, and into philosophy.
Orac) No Bill S if you don't have a "why" you can have a science law but not a science theory.

Big difference between a science law and a science theory.

https://en.wikipedia.org/wiki/Scientific_law
https://en.wikipedia.org/wiki/Scientific_theory

So is what you telling me is you have Bill's law of gravity rather than a theory?

I can't see how Bill's law of gravity is any different to Newton's law of gravity, explain differences please?

You may care to read some quotes of Newton written in 1713 and ponder modern education standards.



Newton man of science knew the difference between a law and a theory and what he was required to do

You will hence forth be known as Bill "hypotheses non fingo"

Hmmm wonder how does GR get from a law to a theory?

You have it easy all the answers are probably written out on the internet all you have to do is know how to join them up.

First principles is fun isn't it Bill S keeps you on your toes now can you walk the walk

Hint: Hmmmm lets think of a question you once answered, Bill S does a photon create a gravitional pull, does a photon have mass and do you consider it matter? Is this consistent with your laws and statements above?

Not ignoring your latest questions/comments; I'm still a few steps further back.



Wikipedia says: “…the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational field which it produces.”

“For static fields, such as …… the gravitational field connected to a massive object, the field extends to infinity, and does not propagate.”

Would it not follow from this that gravity is a static field, and that what is being measured is changes within a gravitational field, rather than any intrinsic motion of the field itself?

There is a problem we are going to confront and you haven't yet got to the point where we have introduced the problem.
So for a change I will sort of give you the problem we are about to hit and you decide what you want to discuss.

In the above you suddenly introduce the concept of a field which your idea and laws haven't even dealt with yet.
I will put that aside as I think you started it as a joke and now got buried in your own joke.

Fields were initially described in classical terms and the man that did the greatest contribution is James Clerk Maxwell. The part you need to read is the history of the equations he derived.

https://en.wikipedia.org/wiki/History_of_Maxwell's_equations

Again I will be brief and just jump thru it just to sequence things for you. The key point about the equations is they connect electricity, magnetism, and the speed of light.

The problem with the equations and what we call "Maxwell's equations" really are not exclusively Maxwell's at all and its covered in that history. What you need to do is add in the concept of lines of force and vector mathematics to Maxwell's work.

The evolution is well covered in
https://en.wikipedia.org/wiki/A_Dynamical_Theory_of_the_Electromagnetic_Field

It is actually discussed in that link that we are going to hit another complication. All that early work is classical and suddenly we are going to need to consider motion and especially speeds getting near the speed of light itself.


What we are describing is the connections of how and why GR (via it's connection to SR) isn't a law but is indeed a theory and Einstein makes it clear he is seeking to do that by this statement .. sigh I am doing your homework again .


Remember the requirements of a new theory to replace an old theory or laws it must explain all that the old covers and he makes that claim.

Finally we can address your question above and the problem rolls around motion. So do you think you are going to be able to use static field ideas on universal bodies that may well be moving at speeds a good fraction the speed of light? What they sort of hide in the statement above is they expect large objects not to be moving very fast and they sort of wave there hands and say we can thus treat them as static ... that is classically ... it's a justification not a statement of truth. You run into this problem with black holes, a spinning black hole vs a static black hole are very different beasts.

So the statement may be valid in a context of use, where classical physics and static fields would provide a correct answer and you can justify ignoring Special Relativity.
So for a more precise personal view I would need to see the full context. If you are asking is that some sort of "absolute truth" then no Special Relativity is the correct answer in all situations Einstein told you that ... don't you believe him

Bonus hint: In the second link was a hint for your journey, let me isolate it "Maxwell's equations can also be derived by extending General Relativity into five physical dimensions."

If you were trying to be cute and got caught let me show you the problem

GR equates local spacetime curvature (expressed by the Einstein tensor) with the local energy and momentum within that spacetime (expressed by the stress–energy tensor).

You have got the first bit you are totally not getting the second bit and haven't introduced it.

The answer starts in the Maxwell link under the section Electromagnetic stress–energy tensor under a curved spacetime (the bit you have got)
https://en.wikipedia.org/wiki/Maxwell's_equations_in_curved_spacetime

As part of the source term in the Einstein field equations, the electromagnetic stress–energy tensor is a covariant symmmetric tensor and that tensor is trace-free or in other words ZERO. Don't fall into the hole that Bill G and Rede did that is very important you need other theories if it isn't true. The justification for the ZERO is electromagnetism propagates at the invariant speed (being c) and conservation of energy in interactions.

You should get the joke when I was asked to define the GR stress-energy tensor and I said Zero. It went straight over some people heads

So you can't directly calculate a stress value and you probably can guess why because we actually have nothing to relate it to and so we have to create an indirect measure or a pseudotensor.

In lovely technical language we say this

It does lead to a problem people may and can choose a different tensor definition and again technically we say this

Don't get hung up on it you have seen this everyday or your layman life think metric/imperial

If someone uses a different pseudotensor they are describing the same thing in different units and some conversion exists just like metric/imperial.

So you can see my answer of zero was both accurate and a joke and they made it funnier by saying I was wrong and didn't know what I was talking about

If Bill G/Rede were more switched on I would have done the GR chicken stress tensor (a play on horse/chicken power) to make a point the choice isn't important

Ask a layman there weight in cartons of beer, sexy girls, sheep manure, feathers etc no problem, but take the concept into a more abstract form and they don't get it

Humour aside generally you try a choose a pseudotensor that is not contentious and easy to replicate by anyone and most in the field would know several some examples Einstein, Papapetrou, Bergmann and Møller pseudotensors. If you say look at the Einstein pseudotensor it has a problem it is not symmetric and runs into problems with angular momentum but the name makes sure it is still around today. You really need someone with deeper GR knowledge than mine to give you pro's and con's or each.

Here is the whole lot I have run thru with less detail in layman style
https://diracseashore.wordpress.com/2009/01/21/everyday-physics-the-stress-tensor/
See how you go.

May be a couple of days before I can get back to this, but I'm still here.

We should clarify a few things.
1. I’m not proposing a theory.
2. I’m not trying to be clever.
3. I’m not trying to score points.
4. I am trying to learn.
5. If I suggest something might be the case, I am happy to have it confirmed or shot down. Either way, I learn.
6. If you are trying to bog me down in maths or obscure science, don’t bother. It’s too easy so it's a waste of time with.

I have enough training and experience in teaching to know that answering a question with a question is a standard didactic technique, but to treat it as though it were the only technique often results in missing important points. I’m too old, and too short of time to take the long route to everything, so a few straight answers would be appreciated.

I’ve had a look at your links and suspect you may be trying to drown me in maths and tech stuff.
Let’s step back a bit.







If you want me to try proposing an idea (I will not call it a theory), I’ll have a go, and try something a bit more imaginative than "God tells it".

QM indicates that zero is not a possible value of electromagnetic energy. The Casimir Effect supports this.
QM tells us that matter is composed of wavelike energy. We might conclude from this that empty space and matter are the same thing, differing only in their energy states. We might continue this line of thought to say that matter/energy and space/time are the same thing. Changes of energy in matter may lead to detectable changes; e.g. expansion/contraction. The presence of matter/energy in space/time may involve a transition between matter/energy and space/time which results in transitional phenomena, such as expansion/contraction. One might expect that the expansion/contraction would effect both matter/energy and space/time, and that it would be more perceptible in the latter.

The “classic” example of what the Earth would feel (and when) if the sun just vanished is obviously just a thought experiment which relies on a physical impossibility. Matter does not spontaneously appear and disappear.

Excluding individual particles, matter becomes present in masses of increasing size by a process of accretion; thus, the interaction between matter/energy and space/time is an ongoing complex relationship in which the expansion/contraction/deformation of space/time – giving rise to what we experience as gravity – is an integral part.

There is no external influence, the process is integral to the formation and evolution of the Universe.

Point 1)

1.) How does gravity get out of a black hole.








...p1....p2....p3....................M >>> motion





^ F
m

(mass m = We right now are registering Grav. signal from past )


Many years ago ( 1000.......00000 Light Yers) Big Mass M was in past in point 1..2...3...

small mass m ( we right now ) are registering very very old position big mass M


WHY WE CAN NOT SEE big MASS M why it is BLACK HOLE ?


light must hit black hole and back to observer ??? Yes
please use HUGE DISTANCE and INVERSE SQUARE LAW


What is very intresting ! small mass m is registering force but
big mass M is not registering any force that is can slown down motion ( I invented this effecte - it is ACTION without reaction model NEWTON III law is too short to be real )



I MADE VERY IMPORTANT DISCOVERY ( easy to prove )
NOT EXIST IN UNIERSE LINE MOTION ( mass m1 is not falling down on mass m2 MASS m1 IS FALING DOWN ON POINT WHERE m2 was in past )

m1=m2

..1...2...3...m1 >>> motion


..1...2...3...m2 >>> motion


mass m1 is faling down on point p1,p2,p3 ....









Point 2)

2.) Why is the speed of gravity restricted to the speed of light

To understand what is Gravitation we must study very old Fact for physics


short theory :

James Clerk Maxwell, in 1861–64, published his theory of electromagnetic fields and radiation, which shows that light has momentum and thus can exert pressure on objects.


Engineers are using Si units system not Idiotics theory


ENERGY / SPACE = Joul/ cubic meter

N*m/m^3 = N/m^2 ( PASCAL !!!! )


http://2.bp.blogspot.com/-C1cgolGV6r0/VUCw2IWncwI/AAAAAAAACWQ/8RhssZGNGKA/s1600/22.JPG



GALILEO NATURAL FALL LAW = MISTAKE

we remember famous experiment on Moon


please compare natural fall down time

1 kg steel ( 7850 kg/m^3 ) and 1 kg EPS ( 58 kg/m^3)

we can compare steel and wood ( remember about Maxwell 1861)

http://4.bp.blogspot.com/-AOVx_ljzTqQ/VP_xutwjrUI/AAAAAAAACQw/HzanrOGF4mA/s1600/CIMG3701.JPG





EXIST TWO TYPES Electro-Magnetic Pascal

Dynamic and Static similar like
Static and Dynamic Air's preasure

We must find ANALOGY !!!( below my interpretation )





IN UNIVERSE exsist many many stars !

Each star is pushing Earth !!! How heavy is Earth

http://4.bp.blogspot.com/-BHgIIFU8ON8/VP_zX3KcL3I/AAAAAAAACQ8/5nk25md2wEk/s1600/CIMG3705.JPG




WE HAVE IN PHYSICS NORMAL AIR PREASURE ., TEMPERATURE and ...

FUTURE MY OWN CLAIM

http://3.bp.blogspot.com/-G8XXBln--6k/VP_2zF35VwI/AAAAAAAACRg/oFtCjI5NMtE/s1600/CIMG3703.JPG






GRAVITATION it is ELECTRO MAGNETIC CAVITATION

Earth is like a big truck
PLACE WHERE EARTH WAS IN PAST = LOWER DENSITY AREA chamber

( photons from stars are hiting Earth - dark colour ground or water ( mirror) energy is changing form

http://2.bp.blogspot.com/-XpgMRvGldH4/VFTgIuJjM3I/AAAAAAAACC8/sBIWRXC5fF4/s1600/CIMG3377.JPG


http://2.bp.blogspot.com/-iNHYy6u9bRg/VF9En99DNmI/AAAAAAAACFA/vOX3fZYchx4/s1600/em.jpg




VERY IMPORTANT PROBLEM FOR PHYSICS
MOTION !!!!



m-----M------m >>> motion ???

how big force is registering left /right m ?

very important is place where Gravitation started life

http://3.bp.blogspot.com/-fEJmNXHYWEE/VUOIBqAuAGI/AAAAAAAACXM/9gbCFna4fb0/s1600/333.png


http://2.bp.blogspot.com/-bi__UJHCX-Q/VUmXV-mvsvI/AAAAAAAACYs/w8VIgCYDGfQ/s1600/grav.jpg





NEW PHYSICS YES WHY NOT !!!

MICHELSON MORLEY BUT !!!! FORCE EDITION

http://3.bp.blogspot.com/-mfX1X9yDqDw/VLuo2Th_6_I/AAAAAAAACNQ/YaGD36e4PRk/s1600/mar.jpg


https://youtu.be/K8aJHtvlBzw

Ok you are dealing in a complex area and I don't like to say "this is the answer just trust me", it is important you make sure the answer you arrive at you are happy with the logic. I can give you what I think but I will draw short of saying this is the answer.

Ok you have bought in QM which technically isn't need to do GR but lets go with where you want to go. QM and Electromagnetism are formally joined in the theory of Quantum Electrodynamics and it is one of the most tested and precise theories in our science knowledge. It is a relativistic quantum field theory and that means it incorporates relativity (specifically Special Relativity), QM and electromagnetics and so it embodies 3 other sets of understanding within it. Yes along with the casmir effect you therefore arrive at a vacuum expectation value of energy in each point in spacetime.

There are however some problem worth noting, if spacetime is infinite in it's points in space your universe vacuum energy is an infinite quantity. When you use the value you get as a quantum gravity theory the value you get for the cosmological constant is massive compared to it's measured value.


No there are extensions of QM that do that but not all, is it the favoured possibly but again science isn't a consensus vote you can take a personal view on that issue.

You may care to review the tenets of quantum mechanics which says none of that except the wavelike behaviour bit.


Ok now you are getting in to trying to describe interactions and we need to get into details and perhaps I will give you some.

What Einstein noticed is that forces can arrive centred on a point in space based solely on motion you know these as centripetal forces in classic physics. There are several key points to this so lets deal with them

1.) The "fictional force" is focused to a single point in spacetime
2.) The force seems to be transparent to the focal point in spacetime. That focal point in spacetime does not see the force like a media would and you can't seem to create a force so large it crushed or shatter the point. This goes to the point that GR locally takes it's stress tensor to zero and you can't directly measure the force directly on a single point in spacetime well at least one that non zero.


One might expect it based on the matter/energy but the above detail casts a lot of doubt on space/time because at the interface we see and measure nothing.

However what Einstein also realized is he had seen behaviour before in hydraulics. He also knew a basic fact that hydraulic systems will work most efficiently if the hydraulic fluid used has zero compressibility and zero viscosity. Think about the behaviour above. What he ended up at was very different but it was a useful starting point. I am not sure how much you want to go into that so leave that up to you.


As far as we know all that is correct


Yes but there is a problem does the gravity come first or the particles, you have a chicken and egg problem.


Simply no way to answer that we have no evidence there is an external force but let me give you a stupid answer which at present you cant refute. Gravity is because a big green giant has the whole universe in his hand and is swinging us around and it is really the centripedal force of that motion.

If you want to review the basics of QM Lubos has just put up a new article on the basics of QM which is worth a read.

http://motls.blogspot.com.au/2015/07/boolean-logic-is-sufficient-to-work.html#more

Again all this is up to you but as you will note is doesn't say the sorts of things you say above.

Acion without reaction !
[b]F1 = F2 = Gm*M/ R^2 ?



mass M was in past in point p1..p2..p3..
How small m is able give the same reactions to big M ???


EN https://youtu.be/tEv6GxLPJRA

PL - https://youtu.be/vMJjuYJSxDA

Orac, perhaps we should examine my earlier post a bit more closely.

1. QM indicates that zero is not a possible value of electromagnetic energy.
2. QM tells us that matter particles behave as waves.
3. This is sometimes interpreted as saying that matter might be composed of wavelike energy, with particles appearing as disturbances in the energy field.
4. This matter/energy duality accords with the concepts of relativity – E=mc2.
5. If statement 1 is correct the vacuum always has non-zero energy, which takes the form of (virtual) particles and waves.
6. Relativity indicates that space and time are linked in such a way that they cannot be thought of as individual entities.
6. This leads us towards a scenario in which a qualitative similarity appears to exist between matter/energy, on the one hand, and space/time on the other.

I agree with everything except the last statement

In general I agree with you to a points 1-5 about QM. However QM is not clear about the structure of spacetime other than Space and time are continuous. QM research has considered the possibility that space or even time are discrete but such theories are inevitably inconsistent.

In fact there are two alternate ways to deal with spacetime in QM which contrast to position space you are familiar with in classic physics.

a) Momentum space (https://en.wikipedia.org/wiki/Position_and_momentum_space)
b) Phase space (https://en.wikipedia.org/wiki/Phase_space_formulation)

So sometimes for ease of analysis spacetime is turned into something classically we would not recognize but the treatments are valid under QM.

People view this many different ways from a simply mathematical thing to it is implying something physical and I leave that as an exercise for you if interested and I am happy to answer questions.

Statement 6 directly link space and time in GR correctly.

So I can't in good faith say I agree with the last statement (which should be 7) because whether the two concepts smoothly join is not clear at least to me.

However this is not about me, if you are happy that all connects I won't strenuously object and lets see where you go next.

I wish I knew! Possibly good to get this distraction out of the way first.

QED describes the strong, weak and electromagnetic forces in terms of exchanges of messenger particles. It seems reasonable, therefore, to use the same description for gravity, although the graviton, which would be the messenger particle, has not yet been found.

A quantum theory of gravity would necessitate the reality of gravitational waves which, like gravitons, have not yet been observed. There is indirect evidence of the existence of gravitational waves, and if they exist, it is reasonable to consider the graviton as an excitation of a wave in the gravitational field.

An electron is considered as being surrounded by a retinue of virtual photons, constantly appearing and disappearing, and the energy of this combination is calculated as going to infinity in the case of each electron. In the same way, every matter particle must be considered as having a similar retinue of gravitons, the energy of which would go to infinity.

A serious consideration here is that, unlike photons, gravitons would interact with other gravitons. This means that any situation involving loops escalates into multiple loops-within-loops. The energy of each of these loops goes to infinity, so in each case infinities are multiplied - infinitely.

Is this an impediment to finding a quantum theory of gravity?

Renormalization is the standard method of dealing with infinities in these calculations, but that is nothing more than the dubious practice of dividing “both sides” by infinity. As a non-mathematician I can do no more than acknowledge that renormalization seems to work, and is valuable in making progress, but how far can that progress go?

Yes it's a Quantum field theory and so that is how it works.


Yes but nature may not care to be reasonable


Ok you are mixing up things here a gravitation wave is a ripple in spacetime metrics in GR theory.
A graviton is particle or virtual particle in a gravitational field theory.

So we have seen indirect evidence of a gravity wave but no indirect evidence of a graviton.


Yes, No, Maybe you have so many different concepts mixed up it's hard to work

Lets start with what a Field theory says, so start here
http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-higgs-faq-2-0/

The key points as Matt underlines

a) A field is present everywhere in space and time,
b) The field can be, on average, zero or not zero, and
c) Can have waves in it.
d) And if it is a quantum field, its waves are made from particles.

So a GR gravity wave is (c) while a graviton is (d) if that helps above.

He further distinguishes by referring back to earlier articles that a "virtual particle" is simply a disturbance in the field, a "real particle" is a resonant wave that persists in the field. There are other tricky things about virtual particles that they do not have to precisely obey particle behaviour because they are short lived
http://profmattstrassler.com/articles-an...-what-are-they/

So under a Quantum field theory your whole statement is misguided and/or wrong the correct field version he expresses as


In itself the statement won't cause you any issue as a layman, until I point out you and your entire classical universe is therefore nothing more than resonant waves in the fields in spacetime. At which point you usually run for the door, you saw the movie Matrix and didn't like it .

So no quantum field theories dispose of classic physics and are very different to the concept of considering virtual particles as real (classical objects) and popping in and out of existence. You do that and then try to borrow calculations from QM field theory, and put simply you can't. You either accept your classical world is gone (IE we have a quantum universe) or rework your theory/ideas from scratch with classical objects and new classical calculations. You are not alone Bill G/Rede struggle a lot with the same issue.


That is not what renormalization is but it probably isn't important if you get the message above about mixing different ideas.

Sorry for length I tried to shorten responses up as much as possible.

I debated whether to discuss real vs virtual particles in QFT so I will put this bit as a new post, it may interest you.

In a practical sense deciding if a particle is real or not is very problematic especially to try and do it classically.
Wikipedia does a terrible job, there is some discussions going to try and clean it up and it ends up at this statement

https://en.wikipedia.org/wiki/Virtual_particle

They have done what you did combined many different ideas and tried to join them into an encompassing statement.

Under Quantum Field Theory that statement is blatantly wrong there is a clear definition like so

You can actually prove the statement by a rather long calculation.

So QFT puts a clear definition under the decision, you find a particle violating SR and it is virtual or just a disturbance in the field using Matt's terminology.

In this regard QFT is unique in that is explains why and what Virtual Particles are.

In order to move towards a QT of gravity, would we not have to consider what Strassler refers to as “quantum waves” in a gravitational field?
How else would we explain gravitons, which would seem to be essential to quantum gravity?

I saw all the Matrix films, and enjoyed them.

The idea that the “classical universe is therefore nothing more than resonant waves in the fields in spacetime” certainly doesn’t cause me to run for the door. It fits beautifully into my ideas about infinity, but let’s not go there! :P

BTW, I’ve read Matt Strassler’s article about virtual particles a couple of times; it’s probably time to read it again.

I'm very happy with long posts, as long as they say something, which (in this thread) yours do.

Yes everyone has tried but there are some very obvious problems and the reasons.
I will offer a general view on the underlying issues, consider it personal not a science consensus view.

QM mathematics and formulation is very exact and there is only one solution you saw that in above discussion.
However the issue is the solution doesn't resemble the classic world so it cause interpretation issues with the classical world.
You just ran thru that above where the world under QFT looks very different to our perceived world.

GR unfortunately is not so exact there are actually many solutions to it's equations.
I would strongly recommend you looking at exact solutions to GR article
(https://en.wikipedia.org/wiki/Exact_solutions_in_general_relativity)
The point is that GR may be considered a kind of compatibility condition not a specific solution.

I was trying to get you to look at the stress-energy-tensor because it shows you the problem of multiple solutions.
It isn't well covered in science media and the same with dark energy, I think largely due to resistance to GR in the past.
You can have fun with those who rely on Science magazines and don't know the background if you are mean
I was hard on Bill G/Rede because they made out what they said was scientific and it simply wasn't, it was more like Marosz.
I may have been brutal to someone else over infinity

If you want a comparison here is a list of the current wiki exact solutions in QM
https://en.wikipedia.org/wiki/List_of_quantum-mechanical_systems_with_analytical_solutions
There are probably many more in literature and on the internet.

QM can not be refined it gives just one answer, GR gives many and in a nutshell that is the problem to me.
So to me we are only going to progress by finding the exact solution to GR or some observation pops up to show us the way.
QM science can and does construct many theories that are compatible with GR but it would come down to luck in finding the right one.
I think string theory is an expression of that and why it offers seeming limitless candidates.

It's up to you but armed with that background it might be interesting to look at traditional GR gravity waves under different stress-energy tensors.

I can't imagine who that would have been. If he even noticed he probably thought "What does he know about infinity?"

I would probably need some very basic background on tensors before I could do much with that.

You are over thinking it .. start where we all started including Einstein

You have a perfect fluid consider the pressure on an individual molecule in the fluid.

http://www.zweigmedia.com/diff_geom/Sec12.html

You don't even have to really follow the mathematics just follow they are describing the pressure at a specific point and trust there mathematics.

The key point here is it is a calculation in general you can never actually measure but it doesn't mean it's useless

In the real world the fluid would be less than ideal so it may compress, change viscosity etc which is the reason the calculation was first done.
Do you remember the post I calculated the pressure at the centre of the earth ... very similar
I smile because good luck ever measuring it.

To make electomagnetism relativistic you give it the same treatment
https://en.wikipedia.org/wiki/Electromagnetic_stress-energy_tensor

You will see it ends up having the same properties

What we are dealing with has a scientific name called a body force.
https://en.wikipedia.org/wiki/Body_force


It's that issue that leads to most of the complications from what many did with contact forces at school.
When you throw the frame of reference stuff in on top it gets very complicated.

As we have strayed into fields and particles, I think this would be a good point at which to check some of my thoughts/questions on that subject.

1. So far, what I think I have is that fields permeate the cosmos. (Is this theory, or is there any way in which it has been/could be established?)
2. On average, fields may be measured as zero or non-zero, at any point in space. (Is that their energy?)
3. We detect fields by observing disturbances in them.
4. I assume this also applies to the gravitational field, because, although gravity waves have not yet been observed directly, we can detect it only because it is disturbed by the presence of matter and/or energy.
5. The normal form taken by disturbances is that of waves.
6. In quantum field theory the waves are [also] particles. (Are there any fields that cannot be described as quantum fields?)
7. All particles are associated with fields, but only at quantum level is this of significance in the present state of our knowledge.

That is all pretty much spot on what science says, I will expand a couple of points.

1. So far, what I think I have is that fields permeate the cosmos. (Is this theory, or is there any way in which it has been/could be established?)

QFT goes a little further and says fields make spacetime and consider it to be a physical entity.
GR doesn't go that path because it is based on a classic field in it's inception.


Do you see the subtlety you can expand/contract spacetime, and there is an outside spacetime.
So QFT definitely takes an approach some other areas of science might not agree with.
You may want to consider your favourite infinity under that.

2. On average, fields may be measured as zero or non-zero, at any point in space. (Is that their energy?)
Agreed

3. We detect fields by observing disturbances in them.
Agree and science detected the higgs field in exactly that way.
If you produce a certain collision it reacts with the field and you see the disturbance as a
short lived virtual particle we call the Higgs boson.

4. I assume this also applies to the gravitational field, because, although gravity waves have not yet been observed directly, we can detect it only because it is disturbed by the presence of matter and/or energy.
Agreed and science is uncertain yet if gravity is a quantum field or a classic field.

5. The normal form taken by disturbances is that of waves.
Agree and extend.
The waves are the exchange of energy and the maximum speed of the waves is the speed of light.

6. In quantum field theory the waves are [also] particles. (Are there any fields that cannot be described as quantum fields?)
Agree and gravity may not be a quantum field.
Our current best theory to described gravity is a classic field theory.
Ultimately if gravity is quantum it would follow the normal QFT transformation done on other fields.

7. All particles are associated with fields, but only at quantum level is this of significance in the present state of our knowledge.
[/quote]
Disagree even in a classic sense you have a problem of the chicken and egg scenario, I sort of bought this up with the electron.
So an isolated electron produces and has a field around it at school you may have drawn it like this



See the problem is the electron producing the field or merely visible because of the field.

Classic physics assumes the electron is producing the field and it radiates out to infinity.
QFT says the field was always there you just made it visible by putting a particle at a point.
QFT also says it is correct because of the discovery of the higgs you can't see or even deduce that field in classic physics.
So science answered the chicken and egg question conclusively .. classic physics lost

However definitions on "the universe" got a little more interesting didn't they
You may care to think of a particle moving vast distances without losing energy in that scheme
Which scheme does QM entanglement make more sense in

If you ever wanted in a nutshell why classic physics is incompatable with QM there it is.
Bill G doesn't like it but classic physics can lead to really wrong answers ... like above
You see classic physics isn't approximately giving the right answer or understanding, and we are going to need to rethink teaching this stuff.

The take home memo is we are never going back to classic physics and QM is never going to disappear, the higgs told you

Here is your classic physics

On cue for you today the announcement of the discovery of the Weyl fermion by two different groups

http://phys.org/news/2015-07-year-massless-particle-next-generation-electronics.html
http://phys.org/news/2015-07-weyl-years.html
http://spectrum.ieee.org/tech-talk/semic...ter-electronics

Background how the Weyl fermion fits into QFT.

http://www.quora.com/Quantum-Field-Theory/What-is-a-Weyl-fermion

They have long been sought after because they give you the equivalent to superconductivity at room temperature.

There is no indication of whether these things are likely to show up in the wider universe.
Everyone is hassling the experts in the "standard model and beyond" for that answer as it is outside the realm of QFT/QCD

Lubos Motl covered it superficially back in an article in 2010
http://motls.blogspot.com.au/2010/12/beauty-of-dirac-equation-and-its.html


Watch what insights the theorists can give but in general massless particles must be massless for a reason and of coarse there are versions of string theory that predict it, which will get a lot of interest now.

Using the tools of QFT it was always known you could not show that massless charged fermions did not exist and hence the search so a hint of physics beyond the standard model.

Given you know the basics as a layman now, I would be interested in your evaluation of the different science media articles on it.

Interesting looking links, all I need now is time to read them.

In the meantime, I assume you know about the pentaquark.

http://www.nature.com/news/forsaken-pent...=NzIxOTI5MjIzS0

My apologies, AR11, I,ve just realised you beat me to the pentaquark.

So a small challenge Bill S. Using your new understanding describe the good and bad in this article

https://medium.com/starts-with-a-bang/embracing-your-fifth-dimension-2e02d9a0572c

Do you think it successfully portraits an accurate representation of science?

My personal view is it basically comes across as an anti-string rant, which isn't really even relevant to many holographic theories. It then tries to put together a mumbo jumbo argument around what it refers to as a bulk spacetime which actually it doesn't ever define. I know what a spacetime bulk is in string theory but it doesn't make sense in this article which basically tries to avoid the stringy stuff.

The key point is it completely misses the fact in physics we are now forced to treat particles as excited states of an underlying physical field that is always already there. That is what makes it look holographic and is at complete odds to the classic physics where the field arise and expand out into space. Many people who don't believe in string theory accept and believe in a holographic scheme.

You said it yourself under QFT you are forced to see an electron or any "real" particle in classic physics as a sort of hologram of the field (Matrix like) ... it's not complicated and nothing to do with string theory or space bulk or the rest of the trash in the article.

Again it looks like another one of those situations that is an article by someone completely out of there depth. If I was being honest it looks like a case of google "holographic principle" and try and write an article using lots of catch phrases and google only picks up the story when the idea is formalized into string theory.

The article as written should have been called AdS/CFT correspondence and basically follows this story
https://en.wikipedia.org/wiki/AdS/CFT_correspondence

Perhaps had they googled a little better they would have found
http://www.thedailybeast.com/articles/2014/08/31/is-the-cosmos-just-a-big-hologram.html


You will also find conflicting claims of who created the concept of holographic principle. The earliest reading I know of the claim is 1947 by Denis Gabor who actually invented Holography and want a guess what made him think of the idea
https://en.wikipedia.org/wiki/Dennis_Gabor

Perhaps I could suggest a reasonable read
https://books.google.com.au/books/about/...amp;redir_esc=y

I graded the article D- as misdirected or misunderstanding.

BTW Bill S if you want a funny read on holographic principle without string theory

http://arxiv.org/abs/1004.1285

Solves the whole thing in only 9 pages and 7 formulas

I love this bit

Looking back through my notes from a few years ago I found:

“When scientists, such as David Bohm, and authors, such as Michael Taylor describe the Universe as a hologram I very much doubt that they are suggesting that some other-worldly being is projecting laser images with an incredibly gigantic projector to produce what we experience as the Universe. I suspect that it would be more appropriate to say that the three-dimensional images we can produce with laser technology are as near as we can come to producing an effect that, to some extent, mimics the way in which our Universe works.”

I found quite a bit of Taylor’s book interesting, but from what I remember of it, I would have thought it would have been too much like “quantum flapdoodle” for your liking.

Still trying to find time for the other links, but will get there.

Ah yes now you mention it, I remember David Bohm and yes a different type of holographic universe. I think that also underlines the general idea has been around in many forms for a very long time. I sort of suspect the concept goes back even further than 1947 probably into the 1920's.

For example Kaluza–Klein theory published in 1921 was a classic theory with 5 dimensions and later adapted into string theory
https://en.wikipedia.org/wiki/Kaluza-Klein_theory

I always viewed it as a hidden dimension theory but using your definition above I think I could argue it qualifies as a holographic theory.

https://medium.com/starts-with-a-bang/embracing-your-fifth-dimension-2e02d9a0572c

“These dualities are said to be “holographic” because they tell us that everything allowed to happen in the bulk space-time of the gravitational theory is encoded on the boundary of that space.”

I find this boundary concept puzzling. Are they saying that our Universe is part of “the bulk”, bounded by 2-brains that form a 2-D box?

Alternatively, could it be that our Universe is considered as having a boundary, beyond which there is nothing?

It's branes not brains BTW

As I said the whole article reads as like mumbo jumbo to me, a bit like when science magazines try to describe quantum entanglement.

I simply don't get anything that means holographic out of "everything allowed to happen in the bulk space-time of the gravitational theory is encoded on the boundary of that space."

I am not a wordsmith but if I had to try I would go something like this

"The universe in classic physics is described by 3 dimensions and time. Brane models in string theory can use the hidden dimensions of space to project a 3D world onto a normal 2D plane in the same way as computer games do it. Electromagnetic, Strong and weak nuclear forces play out only on the 2D plane while time and gravity play out in all the dimensions but project onto the 2D plane. The 3rd dimension is an illusion and hence this is called a holographic theory".

Hard to work out what boundary is being discussed in that mumbo jumbo. If I had to guess, I think the Brane/other dimensions boundary.

All theories that comply with QM/QFT make a definition of fields that propagate a translationally invariant spacetime. So there are a number of possible boundaries in that definition not just one

Now you have progressed I will give you a more interesting boundary to ponder

Emmy Noether demonstrated that conservation laws are linked to symmetries, specifically the validity of the energy conservation law is equivalent to the time-translational symmetry of the laws of physics. So outside our universe must be somewhere time-translational symmetry doesn't hold

An outstanding example of a Freudian slip!



Of course it is! If there is anything outside our Universe it is the cosmos which is infinite. No time, no change, and it's not really outside, because our Universe is "part" if it, and every part is the whole...."and I am that"

Where's Rev when you need him?

Haha you got the joke ... you have come a long way
Didn't some scientist once give you that answer?

If we were religious we just proved we are in hell and that outside our universe is heaven.
Outside here they get everything, land of milk and honey and all that and I did say I was the devil
See you always suspected it was bad here and now you know why

I am guessing you are ready to put it all together and Lubos did it really well in an article 5 years ago, you should be able to follow it now.

http://motls.blogspot.com.au/2010/08/why-and-how-energy-is-not-conserved-in.html

You will meet all the key points again from GR
- Why and how the Energy-Stress-Tensor is zero AKA Vanishing Energy
- Reparameterizing
- Energy conservation

Finally you should see the whole lot collapses like a deck of cards the moment you introduce an actual infinity.

Hence you now know anyone who makes a statement about GR and includes an infinity hasn't got a clue. Some who do it will surprise you

Anyone who tries to use consensus or claim authority, be comfortable that the janitors of science don't care

I put this in a seperate post as it's up to you if you want to look at it.

You may be ready to follow the next extension now as well, if you write all the above out you get this.
https://en.wikipedia.org/wiki/Vacuum_solution_(general_relativity)
See if you can follow it

It answers a couple of problems with gravity you introduced
- Why determining the precise location of this gravitational field energy is technically problematical in general relativity
- Gravitational field energy itself produces more gravity.

The last one at the very least should raise your eyebrows about perpetual motion and why doesn't it go into self induced runaway.

Remember in your first answers I was quizzing you about this and how your theory stopped it

BTW if you want a good laugh
http://phys.org/news/2015-07-line-quantum-classical-world.html
You should easily spot the problem, at 80 I think it might be time for the professor to retire

I have tried thinking as I did about infinity a few years ago, taking one step at a time and seeing how far I can go. This time I worked backwards, trying to understand the origin of a black hole’s gravity. Where does it start?

In the case of a black hole that originates as a collapsing star, the star’s gravity is already there, and measurable, before the collapse. The gravitational field of the black hole can be calculated in terms of the gravitation of the original star.

Black holes are generally presented, at least to lay audiences, as things of enormous gravitational attraction. I think the next step in my line of thought would have to be to ask if the gravity at the event horizon is any stronger than the gravity would have been at the surface of the original star. If it is not, then there is no “escaping” gravity to consider; no one/nothing outside the event horizon experiences gravity beyond that of the original star.

It's more complex and interesting than that consider the first part of this
https://en.wikipedia.org/wiki/Supermassive_black_hole

You didn't touch the gravity creates more gravity why doesn't it go into runaway collapse on itself?

I appreciate that supermassive black holes present their own problems, that's why I said: "In the case of a black hole that originates as a collapsing star..."

My question still stands: Is the gravity at the event horizon any stronger than the gravity would have been at the surface of the original star?

Yes the gravity at the horizon would be greater than it would be at the surface of the original star. That is based on the fact that the horizon is the surface at which the escape velocity would be greater than the speed of light. Obviously the escape velocity at the surface of the star would be less than the speed of light, so the gravity would have to be smaller. However, the gravity at the same distance from the center of the black hole as the surface of the star would be from the center of the star would be the same as it would be the same distance from the center of mass. I'm not sure if this would be affected by GR variations. My first thought is that it wouldn't, because the total mass would not change much. If anything the total mass of the black hole would probably be less than the mass of the star because a lot of the star would be ejected during the collapse.

Bill Gill

Yes/No/Unchanged depends on who and what you believe

So look at your options

GR & Bill G it seems: Within the event horizon matter has to move outward faster than the speed of light in order to remain stable and avoid collapsing to the centre. However there is an issue with this that a black hole must then inevitably collapse to a singularity and you saw the problem with infinities above, GR itself collapses under that. Different scientist will resolve that problem different ways the common ones

1.) Ignore it and wave hands that will understand it better one day
2.) Treat things inside the Schwarzschild radius in a special way and make there own pet theory up.
3.) Admit it's a problem and currently no solution

There are hints as to how to resolve this but you seem reluctant to look at it .. if you want to try read next bit

Your problem in a nutshell

The fact gravity creates more gravity (I think you got that bit yourself and agreed) means it has to be opposed by something or the moment you created one bit of gravity that point would self collapse to a black hole at that point in a self sustained collapse. In classic physics that is an unavoidable consequence of the mathematics that goes like this

X + a percentage X = Y (Y = 1+X%)
Y + a percentage Y = Z (Z = 1+Y%)
.... etc etc
INFINITY

Your problem above is you want to talk about something without considering what is opposing it

Under your current thoughts any point that creates gravity must instantly collapse to a gravitational singularity don't you think it might be important to fix this up first before dealing with the black hole event horizon

So how do you want to deal with this?

My only reluctance is that I like to think I understand a point, as well as possible, before moving on to the next. So I need to be able to answer questions like: Can we measure gravity at an event horizon of a stellar BH? If so, how would that compare with gravity at the surface of the original star?

As far as the idea of gravity creating gravity goes, I had reached the point of thinking “does gravity create more gravity? That raised a few questions, like:

Wouldn’t it have to have mass/energy to create more gravity?

If it’s not a force, can it have energy?

Manifestly, gravity is not a run-away phenomenon. Is that because something counters it, or because gravity does not spontaneously create gravity. Which is it?

What physical/experimental evidence do we have for saying that gravity creates gravity?

Thanks Bill, I think all that makes sense.

The problem is you have only half the GR theory worked so far.
Your half creates a blackhole immediately any gravity forms, so I can't answer what will happen.

You have a curvature in spacetime in the presence of energy/matter but something has to invert time back to what it was originally. You can make it whatever you like space is elastic, there is a back pressure, the green alien inverts it back but something has to as you have spacetime as passive currently ... see the issue

The problem is obvious if time wasn't restored back there would be this big time curvature tracks carved across space where planets/suns moved thru. It would be like a boat moving thru water and the water not levelling the wake left behind it.

I guess you could go for there is no time in space and things with gravity tow time around with them?
So time would be like electric charge under that scheme I guess intrinsic to matter/energy and space is passive.

Both space and time being passive gives huge issues I need a solution from you


Energy and it does remember its covered here
https://en.wikipedia.org/wiki/Vacuum_solution_%28general_relativity%29




Well radiation has energy is it a force?

See this is where it gets tricky for me I need you to define force are talking classic physics/QM/your own?


How can you get a black hole if it doesn't go into runaway, that is like having an atomic bomb without critical mass ... think about it

History lesson
http://www.physicsoftheuniverse.com/scientists_schwarzschild.html

You don't have any back pressure so any gravity at all will collapse into a black hole as it has to overcome ZERO

As I said I am open for anything you believe lets just see where it goes


Einstein and scientists did some tests on a 1919 solar eclipse for a reason to check the curvature of light from the sun

Here is the problem in it's conceptual form
https://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity

So you end up with gravity as a radiation although it is still unclear to me if you want to treat it as a force or not.

I will put this as it's own comment because it is a statement from me not answering your questions Bill S.

The central premise of GR is that the curvature of space-time is directly determined by the distribution of matter and energy contained within it. What complicates things, however, is that the distribution of matter and energy is in turn governed by the curvature of space, leading to a feedback loop.

That is the nature of the feedback loop in GR, how you want to describe it I leave with you.

Again a statement what opposes gravity in GR is dark energy, it is well covered here in layman terms from the NASA site
http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/

They give you the way Einstein thought of it ("empty space" can possess its own energy), the QM answer (which is wrong) and some other alternates but at the end of the day you end up at this point


Whichever answer you take you end up with something creating a tendency to return spacetime to some equilibrium.

I consider Ethan Siegel did two terrible jobs on it but it might work for you and they end up with a negative pressure on any patch of spacetime
http://scienceblogs.com/startswithabang/...verse-combined/
http://scienceblogs.com/startswithabang/2011/12/02/dark-energy-accelerated-expans/

Sean Carroll does all that in a few tight sentences
http://preposterousuniverse.blogspot.com.au/2004/09/dark-energy-equation-of-state.html

If we have dark energy perhaps one might ask what happens to it in a black hole as it might be important

Some funny things to probe Bill G about his answer but as he isn't talking to me the point is moot

OK. Let’s look at three things I think we have said about gravity.

1. Gravity has energy.
2. Gravity distorts spacetime.
3. Gravity creates more gravity.

In achieving 2 & 3, is the energy of gravity diminished, dissipated or exchanged in any way?

Yes absolutely it is

Read the section labelled work done by gravity
https://en.wikipedia.org/wiki/Work_%28physics%29

That is the classic physics version or you can use the more technical GR version
https://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation

Your current answer means your theory is inconsistent with even classical physics

You theory describes a universe other than I know and is the same league as Marosz at the moment.

Perhaps I can ask are you trying to work this out and why googling it gives weird answers.

"What is the surface gravity of a black hole"

The wikipedia article is accurate but sort of funny
https://en.wikipedia.org/wiki/Surface_gravity

The Surface gravity of a black hole section leads to

surface gravity of a black hole ..... k = 1/4M

Therefore the bigger a black hole mass the smaller value of surface gravity ... no really

Is that what this is all about as you don't really seem to be interested in understanding only the value?

It's very different to the answer Bill G gave but he isn't entirely "wrong" either

We seem to be going round in unproductive circles. Could you identify the "answer" to which you refer?

Lets take the easy one kinetic energy of a non-rotating object moving at velocity

In classic physics you know it by a simple equation

Kinetic Energy = 1/2 Mass * Velocity * Velocity

Lets change the velocity terms into a different form for you

Velocity = DISTANCE / TIME

So Kinetic Energy = 1/2 Mass * DISTANCE / TIME * DISTANCE / TIME

You still think you can randomly change distance(space) and/or time?

Kinetic energy of a moving object going near your version of spacetime distortion is going to be fun isn't it

You might need to be careful changing DISTANCE and TIME or you break all energy equations

KE under Bill.S theory:
The Kinetic energy of an object can be anything as it is dependent on the metric of the space it's in and the time factor of that piece of space. For this reason we have dispensed with Kinetic Energy as a concept as it is utterly useless. All discussion now will be about Bill Curvature of spacetime although it isn't clear how Bill Curvature relates to everyday physics.

It's not even clear to me how I can calculate a velocity I have to ask Bill what the curvature and time is at any given point of space so I can calculate my velocity.

Is the problem clear now?

At the moment you have done a Marosz and broken everything and it's not terribly useful

So can we be serious now and either discuss how GR does it, or you need to start addressing issues.

Apparently not.

I’m trying to learn and understand.

Entertaining as your circumlocutory derision may be, your comments are of little value unless you attach them to the “answer” you are criticising.

A plethora of deprecatory comments, and a surfeit of seemingly sneering emoticons is probably not the most productive way forward.

Let's either get back on track, or stop wasting our time.

You posted this


THE ANSWER IS YES ENERGY IS EXCHANGE IT HAS TO BE!!!!!!

Why ... well it's dam obvious ... Energy is what connects the curvature to the normal everyday physics as we know it, after all the curvature is supposed to be what produces the effect we measure isn't it or vice versa for that matter.

The only thing you can measure is energy, name something you measure that has no energy. That is the funny part of time if you have no energy you can't measure and time is meaningless and where you have gone. I think that area has a name usually covered by religion/philosophy as I can't test anything and I have to believe whatever you say.

If the energy isn't connected, you have Bill Curvature which is random but involves time and Energy which involves time but it isn't connected to the curvature ... say what. One may ask is Bill curvature of spacetime and normal physics time even the same thing if they aren't connected.

So at least in physics if you have time you have energy exchange. If we can measure something different then you have a difference in energy. So gravity produces an effect we can measure so it is exchanging energy. So if Bill curvature is caused by physics or is creating physics it can only do so by exchanging energy.

Now this has got totally stupid and gone Marosz can we get back to reality, we need energy exchange to define time at least in physics. I really didn't think I would have to explain that to you.

Now if you really really want to push the envelope and not have energy I at least need some observable I can test so this isn't a religion/philosophy thing.

Assuming you don't want to push the envelope Bill curvature is either caused by something in physics or something in physics causes Bill curvature it matters not which way. I supposedly can measure a cause and effect so therefore energy is being exchanged.

If you can't do either of above we are back to a Bill's law and I don't really care about Bill Curvature it rates about the same as invisible martians push things down as an explaination of gravity ..... AKA Newton gravity ... AKA you aren't offering any solution so why discuss it as there are plenty of religion/philosophy forums.

Lets see if I want to continue this .. here goes

So am I going to be able to measure something or some effect from Bill Curvature AKA are we exchanging energy?

Leap of faith we aren't doing philosophy or religion we are exchanging energy

I am going to stretch your thinking back from classic physics towards GR. Many of the concepts in GR does not require curved spacetime at all
https://en.wikipedia.org/wiki/Equivalence_principle


So what is the reason you need a curvature of spacetime, well to turn GR into a force that you see in classical physics.


See the simplicity here there is nothing special about matter here it just can't be moved out of the way. So Einstein defined an equivalence of energy replacing your force with spacetime curve. That equivalence links the curvature to energy in a very precise way or to be exact what Einstein says is that the curvature of space-time and Newtonian stress-energy are the same thing.

You are trying to not talk about classic forces, energy and avoid stress energy in your Bill Curvature statements and I am going like what the hell sort of theory is this!!!!!!!

Now it does get more challenging when we can't simplify to a nice reference frame like above but SR provides most of the answers which GR adopts.

To me you are sort of coming at this backwards you are trying to curve spacetime without first working out why you want to do that and specifically trying to avoid incorporating classic physics.

Thanks Orac. A few years ago I was trying (in my low-tech, hitch-hiker way) to argue that causing and maintaining spacetime curvature must involve energy exchange. I was being shot down from all angles. It seems that a more devious approach can elicit quite different results. To be fair, I don’t remember if you were among the shooters, but I have my suspicions.

I just need to find a bit of time to digest your last couple of posts; I’ll be back.

BTW. A silly thought:

Gravity: that which keeps everyone down.
Grabity: that which lets the few rise above the masses.

I can say I hope it would have not been me unless I really didn't understand what you were saying or had a bad hang over. If it was me I was wrong and I apologize because I could not have been more wrong, Einstein says you were right and I accept it

You may officially give me a hard time if I got it wrong and tell me to go fix up the rest of physics I just broke

Here is what you were asking a more technical way
http://physics.stackexchange.com/questions/70993/how-energy-curves-spacetime
Lubos's answer is the most technically correct and he even tacks in the local feedback but I agree the most voted answer is the best layman answer, and best layman formula ever that says basically says what you did in the statement above.

You were right at least until I or someone else can disprove GR anyhow

I am hopeful you get the bit about why the tensor can't be measured directly as anything but zero but it will be very obvious in your surface gravity of a black hole at the event horizon you were doing. Bill G I don't think gets that by his answer to that problem and as I warned you the answer to that problem is actually funny.

This makes little sense to me, unless you mean that as a gravitating body moves through spacetime it distorts spacetime; then something else must act on spacetime in order to restore it to its original, non-distorted, state. Is that what you are saying?

Correct you must force it back or if space is passive have a radiation effect.

Lets take any random point in our solar system it's gravitional distortion is based on the effect it feels from every point in the universe. Lets deal with that not from the really really distant ones but the close ones but the lets say from earth to sun like distances.

You know the calculation the sun is 8 minutes away at the speed of light from earth which is the speed of gravity theoretically. So lets take a point right angles either side of the suns position right now and 8 minutes at the speed of light away. The deformation is some value x. Now roll forward one second. The sun has moved as we were initially right angles (the shortest distance) the distance to us must have increased slightly and so the gravity must drop by a small amount delta so we have x - delta. The key point here that point must not only distort it must undistort somehow.

We are back to the exact same situation as electric charge there are exactly three options here

1. The object is radiating gravity and space is passive. So the gravity at any point in space is the sum of the gravitational radiation of all objects. That is how classic physics taught electromagnetism so you end up with gravity looking like that radiating from everything. You can even end up drawing pretty radiation field lines like you did in classic electromagnetics. Big objects radiate the attractive force more than little objects because they are bigger and we have our theory.

2. The object is passive and space has an energy that can be deformed in the presence of mass/energy but will return back to normal when it moves. We saw this with Quantum Field Theory that particles become viewed as just a disturbance in the field and so gravity would be just some disturbance in some field. Underpinning this idea however is the the distortion of the field is unnatural and the field is fighting to return it to uniformity as the distortion carries energy. Hence a little mass distorts a little way a big mass further, you get your proportionality. In QFT we even had resonant points that could persist for long periods because the resonant point stopped that force being seen and we called them "real particles" and "virtual particles" were decayed by that force. In Electromagnetics we call it back EMF or counter-EMF, the opposition to deform the field. You can't have a field of this type without a back pressure, think about why.

3. Some mix of the above two schemes. We didn't really discuss this with QFT but there could be some sort of mix of both effects. The whole idea called heralding, it's sort of like phone ahead or notify in advance. In QM there are quite a few things that can be setup to be heralded so you know they are going to happen but as you can imagine this would make gravity really complex. This is like hidden variables explaining QM.

So number one would be how Newtonian physics would work with things radiating attractive force. GR fits into two and Einstein realized he needed a pressure to push spacetime back so he introduced the cosmological constant AKA dark energy.

The story is well covered in
https://en.wikipedia.org/wiki/Cosmological_constant

Einstein did it as the article says to "hold back gravity" and achieve a static universe.

My personal views, isolated because it is my view

From reading Einsteins work I get the impression he thought of energy as a "quantity" and the universe as a bath full of it because of the laws of conservation. As he viewed it that way he arrived at modelling the pressure as a perfect fluid. I think his logic was energy had some property internally that makes it want to spread evenly like a something dissolved in liquid solution. As energy clump together it created an a pressure which in a normal liquid solution you would call osmotic pressure ( https://en.wikipedia.org/wiki/Osmotic_pressure)

The reason Einstein made the stress tensor always zero is because he made it like a surface tension of zero in a fluid. No such fluid exists by the way so why do it you ask.

Well surface tension is not a property of materials but of interfaces between two (or more) materials. It is implicit in its definition that the interface separates two kinds of materials that behave differently (otherwise the interface would be just some imaginary surface inside the one material with no physical meaning). In real liquids that surface is indeed subject to blurring because of forces which is why no zero surface tension fluids exist.

Worth a quick look it's short
https://en.wikipedia.org/wiki/Perfect_fluid

I think Einstein wanted a clean division between the energy and its internal pressure and our physical world. It gets messy if you start modelling interface tension in GR and the maths blows up but some people have tried it. So Einstein wanted a clean divide between the energy domain and our physical world, I think the motivation was E=mc2 it's either one or other with c as a constant.

Do you understand now why you are never going to be able to measure the tensor directly as anything other than zero if Einstein is right?

However I also scratch my head if Einstein believed that of energy why did he have so much trouble with QM.

Anyhow there you have it why something called "Dark Energy" is actually needed in any non radiative version of gravity. GR is a non radiative version and has that back pressure inbuilt into it. If you make a field version of GR you must in build the back pressure of deforming the field. Finally the tensor is always zero in GR because of the clean symmetrical interface it defines.

Bonus now if anyone doing electronics asks you what the back-electromotive force or Lenz's law exists you can explain it

You know how I love cosmologists and consensus well apparently I am right to a science confidence of 99.996%
http://www.port.ac.uk/uopnews/2012/09/12/dark-energy-is-real-say-astronomers/

GR isn't my area and I can't go much deeper than this but I do know the basics but I could always be wrong !!!!!

If you understand all that you actually have got generalized field theory understood ... what a field is in physicality that is a whole other story

The other lesson is the one Bill G failed at... look at what is being said, not who said it. For example I always read Lubos Motl on GR even though he is a string theorist because he knows GR very very well, I have seen that on a number of physics forums. Don't take him as gospel but do read what he says very carefully.

Surely this apparent movement is due to the rotation of the Earth. The angle between sun and Earth does not change significantly. Obviously the fact that the Earth's orbit around the sun is not circular changes the angle through the year, but your 1 sec interval is not going to mark a significant difference to that.

Water pressure smoothes out the wake; why would vacuum pressure not smooth out the spacetime distortions?

Could there be a 4th?

The Universe is a gravitational field, particles of matter are distortions in that field. Energy is a distortion in the gravitational field. All other fields and particles are subsidiary to this.

Just a thought.

I didn't introduce Earth there it was a blank empty piece of space? If you want something there lets put a neutron particle there as it will provide almost no other interactions. Sorry I only used earth/sun as a distance because I know you knew the time of flight of light. Sorry my for my bad English again, I concentrate on the translation so much I lost what I meant.

So the point is a blank empty piece of space yet the gravity field must reflect every gravity attraction from every point in the universe and it must go up and down.