Gravitational mass and Inertial mass

Paddoboy, you may find this 'interesting' Duffield has his own forum site...

http://www.physicsdiscussionforum.org/introduction-t6.html
The index page here...http://www.physicsdiscussionforum.org/

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I am going to try to get back on the topic of gravitational and inertial mass. One thing interesting about inertial mass or mass in motion, is the mass, by being invariant, changes the relative reference of space-time, into absolute reference. It has to do with energy balance.

For example, say we are in space without any fixed reference point. We have two masses, moving at relative velocity V with respect to each other. One mass=M and the other mass=2M. If we ignore the mass and look at only velocity, these appear in relative motion with no preferred reference.

However, if we take into account their mass by allowing them to collide, the collision dynamics will be different based on which reference has the velocity. The collision is not relative, even if the space-time reference is. If the M has all the velocity and 2M is stationary, the M will hit 2M, deflecting backwards, transferring some momentum to 2M. If 2M has the velocity, since it has twice the momentum, the collision is different. It will hit M, and make it move forward with 2M still going forward.

Once you add mass to velocity and space-time references, they are no longer relative, since combination of scenarios will have a unique energy balance because of inertia and mass. Relative reference, by ignoring the mass, can violate energy conservation. The space-time construct is not the same as a space-time-mass construct which is far more accurate and more absolute.

In special relativity, Einstein added relativistic mass, to make sure the energy balance is correct. Einstein made provisions for M and 2M collisions at velocity=V------> C, close to the speed of light.

 

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IMHO it's better to think in terms of space, energy, and motion, wellwisher. Remember that Einstein said mass is a measure of energy-content, he said energy causes gravity rather than mass per se, and he gave the equations of motion. Look at the stress-energy-momentum tensor:

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Public domain image by Maschen based on image by Bamse, see Wikipedia

See the pressure diagonal? See the shear stress? What we're dealing with here is space that is modelled as an elastic continuum. Where adding energy results in pressure and strain, because adding energy is like inserting more space. At the fundamental level, space and energy are the same thing.

 

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There you go again.... Before anything of what you say above can have any meaning you would have to present a clear and precise definition of what you mean when you use the word energy.

Yes Einstein did associate the energy associated with a photon with an increase and decrease in the total mass of an atom, as that atom absorbs and emits, a photon..., but the word energy is not limited to the concept of energy as represented in the context of photons. IOW even where we today think of light as a form of energy, that does not make light interchangeable with all other conceptual forms of what we think of as energy. And the association of energy and mass described by Einstein, was theoretical when he initially suggested it and remains theoretical in that context, until someone discovers a means to accurately and directly measure the mass of a single atom before and after an absorption and emission event.

Again, a clear definition of specifically what you mean by energy.., and what is not included as energy in the above is far more important than anything you said... And when you add, "At the fundamental level, space and energy are the same thing.", are you fundamentally sure? Of course you are, even where the use of the word fundamental suggests that the two concepts you shove together, form some composite conceptualization, representing two distict fundamental concepts. Now you need not only a clear and precise definition of what you include as energy above, you also need to add a clear and precise definition of what you mean by space.

Fundamental is the same as reduced to it most basic component. What you are describing is something that, as presented is comprised of more than one fundamental component. Most of the time this is nothing to be worried about. Many physicists think of space as both fundamental and as in terms of some composite.., but they know that is what they are doing and it I generally only within the context of a lay discussion, with other than other physicists, any confusion arises.

Farsight, so far you have not demonstrated that you are one of those physicists or that you fully understand the concepts involved. You are not always alone in that, but you do seem to standout.

 

That picture represents an analogy. The stress-energy tensor does not model space, it models momentum flux. And the tensor is not that matrix; that matrix is merely one way to represent the tensor in a certain way, under certain mathematical condition.

That doesn't seem to match anything in physics. Would you care to produce a mathematical model of your idea that we could compare to observations?

 

I have explained what energy is in the past. There's an old version here. There are later better versions kicking around the internet. Just think about compressing a coil spring. Where is the energy? It isn't in the atoms, it's in the bonds, in the electromagnetic field, in the space between the atoms. You end up with a fundamental definition which is "energy is a volume of stressed space", and that's as far as you can go.

I do not concur with your sentiment that E=mc² remains theoretical.

Yes. Try working it through for yourself.

I've got a Space Explained too. Space is a one-trick pony, and the only trick is distance.

No, there's only one. Space and energy are the same thing remember? If you take energy out of space, it gets smaller. If you take all the energy out, you have no space left.

Space isn't made out of anything else. Instead things are made of it. For example, a field is a state of space. A photon is a field-variation propagating through space. We make electrons and positrons out of photons in gamma-gamma pair production. And so on.

I understand the fundamentals better than most.

 

It isn't just an analogy. A gravitational field really is a pressure gradient in space. That shear stress is for real. Have a look at electromagnetism for stress and strain.

No. Einstein did that. I'm just helping you to understand it.

 

You are confusing two separate things that happen to be represented by tensors, something explicitly warned against in the very wikipedia article that you cited. As per usual, you fail to read your own citation.

Then please show us exactly where in Einstein's use of the tensor in physics these claims can be found.

I don't like that you make me call you a liar, but you have lied so consistently that it is important to tell people that you are lying here as well. You haven't even read any of Einstein's mathematical work, so you will not be able to show us where in Einstein's physics your claims can be found.

 

Get lost. I'm not a liar. Whilst I can't prove that space and energy are the same thing at the fundamental level, there really is an energy-pressure diagonal in the stress-energy-momentum tensor. And a shear stress term. Here it is again:

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Public domain image by Maschen based on image by Bamse, see Wikipedia

Now go and read up on the Einstein Field Equations wherein "the EFE equate local spacetime curvature (expressed by the Einstein tensor) with the local energy and momentum within that spacetime (expressed by the stress–energy tensor)."

 

And here I thought you put me on ignore.

The historical thread link you offer to support your definition, winds up in the Pseudoscience Archives. Not the best reference for a discussion in Physics & Math.

Just where has anyone raised the theory here to the status of proven? Yes, it is widely accepted that E=mc² represents a relationship between mass and energy. Still, ask a sufficiently varied group of physicists and theoretical physicists to explain that relationship, and they will not all agree on the detail. As I said it remains a theoretical relationship, even when there is evidence that supports it.., until it can be objectively and directly observed to be entirely accurate.

Right now Farsight, the evidence that supports acceptance of the relationship still depends upon interpreting data from within the context of the theory from which it is derived. This remains one of those situations where you fail to understand the difference between what we know and what we think we know.., or proven reality and theory.

In your latest post, in this thread.., you state....

which is exactly the opposite of what you have been saying! One of the continuing issues with your beliefs, is that you don't often admit the difference between what you believe and what is real. How are any of to know if you even know the difference?

If you cannot prove it you should not be claiming it to be a fundamental reality.

First, space and energy are fundamentally the same thing.., and then space is only a trick of distance? It almost sounds now like you are running toward an argument that.., it.., is all an illusion... Which philosophically could have legs, but would not be a discussion appropriate for Physics & Math.

Again space and energy are the same thing.., but you cannot prove it? Why even keep saying it then?

Here your argument begins to sound as if reality is defined by the observer. Again a philosophical discussion, but.... You know in some ways this may be, and I say may, because this is a personal on the fly comment, why Einstein moved away from space and its Newtonian context and introduced Spacetime. Space as a Newtonian concept is fundamental, spacetime, which is how we think of space, in this modern era, is a conceptual composite, of independently fundamental components.

It very well may be that when we measure space, something like, the vacuum energy that fills space.., or any assortment of EM or gravitational fields, affects our measurements. Does that mean that space, vacuum energy, EM fields and gravity, are a single fundamental thing? ... Or maybe we just have a hard time distinguishing how several fundamental things dynamically affect our observations.

What is made out of space? What fields? A photon is space or moves through space? And I am still waiting for a gamma-gamma pair production reference that does not require more than a gamma-gamma pair.

Yes, we have all heard you mention that, in one way or another, in the past. There does not seem to be many who agree.

 

I tend not to put people on ignore forever.

You know what it's like here. All the good stuff gets kicked into the trashcan by "moderators" who give free rein to trolls.

E=mc² does not remain theoretical, end of story.

It isn't the opposite. You're clutching at straws.

I can claim it because there's evidence for it.

The fundamental nature of space and energy are most definitely appropriate for Physics and Math.

Because the stress-energy-momentum tensor concerns energy in space, and we cannot distinguish the energy from the space.

No, we don't think of spacetime as space. You might, and others might, but they're wrong. Spacetime is an abstract mathematical model in which we depict worldlines and light cones, but it's static. It depicts all times at once. There's no motion through it or in it. The reality that underlies curved spacetime is inhomogeneous space.

Try separate that vacuum energy from space. When you can't, reason that it doesn't fill space, it is space. A electromagnetic field is a "state of space". So is a gravitational field. That's what Einstein said.

Huh? A photon is a wave in space. It isn't some billiard-ball particle.

 

Since when does the permabanned dropout presume to tell the mathematician to get lost? Oh, I forgot: in Farsight-space, where position is absolute, c = coordinate speed of light, and the moving frame at t = t[sub]0[/sub] is not an infinitesimal, etc. Ah, what a great world Farsight-gedanken must be: all of your dreams come true.

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And by that you mean at the 5th grade level. And even though you flunked out, you're lecturing a professional mathematician.

Oh no you don't. Explain what you mean by "diagonal". And while you're at it, explain "tensor". We all know this wasn't covered in the 5th grade.

Define shear stress and relate it to the tensor. What is the significance of this? Explain.

That does no good, pointing to an illustration. A picture is worth a thousand words. In 50 words or less, explain the picture. You can't can you? This is just like Reiku, waving around the iconography of science, without any clue what it means. So describe it to us, or simply admit that you flunked out of math and science, and then, once it's established that you ARE a liar, we take you to the woodshed for the lie above, claiming "I am not a liar".

:spank:

Said the permabanned 5th grade dropout to the professional mathematician who cut his eye teeth on this. Shame on you for impersonating a fully formed intellect. Don't you ever talk to the experts here again like that.

Bad Farsight!
:spank:

How dare you cite this? You only recently admitted that you had no idea what a field is.

Quote mining won't bail you out. PhysBang tasked you (in part) with explaining the meaning of the tensor itself, in connection with your claim that space is energy, etc. All you have done is put up smoke screens, and exactly in the manner of Reiku. So start with a tensor, any tensor. Tell us what it means. Tell us what the diagonal means. Then take the generalized tensor in question, in the context of the illustration, and explain what it means. That explanation had better match what you just told PhysBang or we're going to have to take you out to the woodshed for lying again:

:spank:

Now, once again: where does anyone say space and energy are the same? First of all, space has units of m³. Energy is in Joules, or if you prefer kg·m²/s². Now set them equal and solve. What do you get? Oh never mind, we all know you flunked algebra:

1 m³ = 1 kg·m²/s²

1 m = 1 kg/s²

What does that even mean? Or how about this:

1 s = √(1 kg/m)

Just wow dude. Space is energy. F'in awesome for an acid trip, but what does it have to do with science? Nothing. It belongs in Farsight-land, where c=coordinate speed of light, position is absolute, derivatives are meaningless, tensors are pictures of strain "across the diagonal", fields are entirely nebulous, math is at the 5th grade level and we make stuff up as we go, griping that all the scientists in the world have it wrong, because a permabanned user says space and energy are the same even though he can't prove it.

So what?
:shrug:

Your posts totally suck. For the love of Pete, go take remedial math and science and leave us alone.

 

Thanks nimbus, I guess I forgot about it. I know I never visited it before. But out of curiosity I took a glance just now. What a crock. He gets kicked out everywhere he goes so he uses his vanity site for a sandbox. What really sucks are the ads. To think trash can be capitalized on. I wonder if the advertisers have any idea it's a crank vanity/trash science site? And I wonder how much competition he gets for peddling junk, given that some fraction of all boards are run by cranks.

And I wonder what he's doing here, still trolling after being permabanned, instead of talking to himself on his own board, where his puppet won't talk back unless he wants it to?

 

Aqueous ''This is just like Reiku, waving around the iconography of science, without any clue what it means.''

Yet you couldn't even understand what a unit pseudoscalar was or what it's meaning in geometric algebra consists of. Stop bad mouthing and attacking and take a good look at yourself ref:


http://www.sciforums.com/showthread.php?142464-The-Motz-Hestenes-Rotation


You show no mathematical understanding, you came in with two laughable faces without indulging in how the math is wrong, not that it is or anything, but it seemed clear you don't know anything about the Clifford algebra's responsible for this geometric understanding.

 

Not, but you do tend to avoid providing evidence forever.

I would love for you to read Einstein, to work through what he wrote and engage it. Instead you use your cherry-picking to avoid dealing with the substance of his work.

Statements of theory must, by definition, remain theoretical. There is evidence for that equation (for massless particles only), but that is evidence for a theoretical statement.

The problem here is that you want to deny every claim that is not directly empirical, Farsight, because you don't want to have to admit that time is an important part of physics and your only argument against time is that it is something that is entirely theoretical (since you ignore our actual perception of time, of course).

OK, so please show us the physics evidence that "space and energy are the same thing". Show us the measurements that provide evidence that these two theoretical entities are the same thing.

If you are willing to produce physics and math.

Distinguishing energy from space is literally what the Einstein Field equation does. In every textbook, there is a discussion of the energy side of the equation and the spacetime side of the equation.

OK, so show us how to do a gravity problem with inhomogeneous space. And try not to produce the kind of response that has gotten you banned at every forum on the internet. Try physics and math instead.

 

Space isn't spacetime! The metric tensor on the left is all to do with your measurements of space and time:

\(G_{\mu \nu} + \Lambda g_{\mu \nu}= {8\pi G\over c^4} T_{\mu \nu}\)

The stress-energy-momentum tensor on the right is to do with a concentration of energy, usually in the guise of a massive star or planet, which "conditions" the surrounding space, altering its metrical qualities. Imagine you’ve placed an array of parallel-mirror light-clocks in an equatorial slice through the Earth and the surrounding space. When you plot all the clock rates, your plot resembles the Riemann curvature depiction of curved spacetime:

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See gravity works like this for more detail.

I'm not banned on every forum on the internet. When I have been banned it's usually for embarrassing some guy who brooks no challenge. Because my physics knowledge is better than his. Here's a paper which shows you "how to do a gravity problem" with inhomogeneous space: Inhomogeneous Vacuum: An Alternative Interpretation of Curved Spacetime

 

All the advertisers care about it how much traffic is generated and if anyone follows a link... I did not add to the traffic.

 

True, space is a subset of spacetime dependent on our choice of coordinate system.

That equation is true regardless of choice of coordinate system, so it is about position in spacetime, not the measurements of those positions.

That looks like a pretty clear distinction between energy and space that you are endorsing, there.

Sadly, a distinct lack of detail there.

I see no physics or math in your response.

An obscure exploratory paper on light bending alone in a Chinese physics journal is not enough when you are claiming that you are offering us the true secrets of gravity. Please do a simple falling body problem using inhomogeneous space.

 

No it isn't. Spacetime is a static abstract thing. There's no motion through it or in it.

You're confusing space and spacetime again. The Earth is positioned in space. Light moves through space. You use the motion of light through space to measure distance and time. You draw worldlines in spacetime to depict motion through space over time, but there's no motion in spacetime. The map is not the territory.

It's enough. And you missed this:

"Einstein’s stress-energy tensor has an energy-pressure diagonal, and to envisage pressure you need to step up from a rubber sheet to three-dimensional space. Imagine it’s like some gin-clear ghostly elastic jelly, then you insert a hypodermic needle and inject more jelly to represent the mass-energy of the Earth. The surrounding jelly is pressed outwards rather than being pulled inwards."

The gin-clear elastic jelly represents both space and energy.

That paper matches what Einstein said about inhomogeneous space. Like Baez said, space is not curved where a gravitational field is. Instead it's inhomogeneous. Einstein said light curves because the speed of light varies with position. Not because spacetime is curved. That's a modern myth that confuses cause and effect. Your plot of optical clock rates is curved because the speed of light varies with position. Not because spacetime is curved. Your lower clock runs slower because the speed of light is slower when it's lower, not because your plot of clock rates is curved.

I told you that matter falls down because of the wave nature of matter and because "the speed of light varies with position". That should be enough. If you want more, read Albrecht Giese's take on it. You will appreciate that there's some things I don't like, but the underlying explanation is essentially the same.

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I find that hard to follow.

May I ask how many years you've said it? Surely it has caught on somewhere.