Theoretically, how does gravity behave inside a black hole?

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Online jeffreyH

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Could gravity wave emissions be more concentrated at the poles in a rotating black hole?
« Last Edit: 09/10/2013 09:38:46 by chris »
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Offline Pmb

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Could gravity wave emissions be more concentrated at the poles in a rotating black hole?
A rotating black hole doesn't radiate gravitational waves.

What is your question about what's going on inside the event horixon, if that's what you meant by "inside" a black hole?

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Online jeffreyH

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Could gravity wave emissions be more concentrated at the poles in a rotating black hole?
A rotating black hole doesn't radiate gravitational waves.

What is your question about what's going on inside the event horixon, if that's what you meant by "inside" a black hole?

It was inside the event horizon I meant and I know it is a controversial question. In what sense do you mean that a rotating black hole does not radiate gravitational waves? Once you have answered I will make some points of my own.
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Online jeffreyH

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Pete

Are there any articles on Beckenstein's upper bound entropy?
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Offline Pmb

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Pete

Are there any articles on Beckenstein's upper bound entropy?
Never heard of it. In fact I've never studied thermodynamics in a relativistic context. One of those "back burner" things.

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Online jeffreyH

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Pete

Are there any articles on Beckenstein's upper bound entropy?
Never heard of it. In fact I've never studied thermodynamics in a relativistic context. One of those "back burner" things.

This is related to string theory and the idea that entropy pertains to surface area rather than volume. It is also related to the holographic principle.

http://en.wikipedia.org/wiki/Bekenstein_bound
[In physics, the Bekenstein bound is an upper limit on the entropy S, or information I, that can be contained within a given finite region of space which has a finite amount of energy—or conversely, the maximum amount of information required to perfectly describe a given physical system down to the quantum level.]
« Last Edit: 05/10/2013 06:36:57 by jeffreyH »
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Offline Pmb

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Quote from: jeffreyH
This is related to string theory and the idea that entropy pertains to surface area rather than volume. It is also related to the holographic principle.
Sorry but I've chosen to learn nothing about string theory. It requires a lot of work to get to that point and I don't read material for the layman. It always gives wrong information and one has to unlearn things so I don't want to have to unlearn anything when I start to learn string theory.

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lean bean

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Could gravity wave emissions be more concentrated at the poles in a rotating black hole?
JH, I think if your rotating black hole is symmetrical, there will be no gravitational waves. Yet, if there are polar jets of accelerating matter originating outside the event horizon, then I wonder if you could have gravitational waves because of this accelerating matter?? That's above the poles.
What about matter accelerating from the accretion down to the horizon, would there be gravitational waves because of this accelerating matter?
Polar jet...
http://en.wikipedia.org/wiki/Polar_jet
« Last Edit: 06/10/2013 19:28:36 by lean bean »

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Online jeffreyH

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Could gravity wave emissions be more concentrated at the poles in a rotating black hole?
JH, I think if your rotating black hole is symmetrical, there will be no gravitational waves. Yet, if there are polar jets of accelerating matter originating outside the event horizon, then I wonder if you could have gravitational waves because of this accelerating matter?? That's above the poles.
What about matter accelerating from the accretion down to the horizon, would there be gravitational waves because of this accelerating matter?
Polar jet...
http://en.wikipedia.org/wiki/Polar_jet

I can't see there being enough gravitational field strength from this matter. One question for anyone with the information. Does time dilation effect the matter below the surface of a spherical mass. We know on the surface it does but does the interior? This is an important question to answer. Particularly with regard to black holes.
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Online jeffreyH

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As momentum causes time dilation and gravity induces momentum, does this mean that gravity should be immune from the dilation? I ask because it is assumed theoretically that the gravitational fields of black holes are frozen. This makes sense as any escaping gravity could upset the balance within the black hole, making it unstable. What causes the big freeze?
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #10 on: 06/10/2013 22:06:55 »
Ah! Ding! The light bulb went on. Gravity IS dilated. How weird. There must be a distinct separation between momentum and gravity. But also a link between light and gravity via momentum. Therefore a link between the electromagnetic radiation and gravitational radiation via momentum. I would argue that this means gravitational waves travel at exactly c. This has implications for any theory of black holes.
« Last Edit: 06/10/2013 22:14:19 by jeffreyH »
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #11 on: 06/10/2013 22:21:39 »
There must also be a separation between light and momentum giving the fixed speed. Momentum is a constant rather than a variable. If momentum is a property of matter then there is no rest frame. The contraction of receding galaxies could actually be stretching the spaces in between. This may mean this intergalactic space is length expanded and in effect speeds up.
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Offline evan_au

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #12 on: 06/10/2013 22:53:34 »
If an object is orbiting a black hole, it will radiate gravity waves, first circularising the orbit, then shrinking the orbit.

A Nobel Prize was awarded for detecting this effect in orbiting neutron stars. The same effect is expected to occur for objects orbiting a black hole.

There are very few characteristics of a black hole that are thought to be observable outside the black hole: Its mass, electrical charge and angular momentum.

See: http://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #13 on: 06/10/2013 23:34:02 »
There must also be a separation between light and momentum giving the fixed speed. Momentum is a constant rather than a variable. If momentum is a property of matter then there is no rest frame. The contraction of receding galaxies could actually be stretching the spaces in between. This may mean this intergalactic space is length expanded and in effect speeds up.

Jeff - May I make a suggestion? There is a modify selection which allows you to modify a post that you've already made. Writing everything in a single post rather in a serious of multiple posts can make things easier to follow for some people, such as myself. :) This is simply a suggestion, nothing more.

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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #14 on: 06/10/2013 23:38:13 »
Quote from: jeffreyH
Does time dilation effect the matter below the surface of a spherical mass. We know on the surface it does but does the interior?
Yes. Gravitational time dilation is a function of the gravitational potetial and below the surface of a gravitating body there is also a gravitational potential. The difference in clock rates is caused by a difference in the value of gravitational potential.

BTW time dilation is the same phenomena as gravitational redshift so expect people to use the terms interchangebly. See http://home.comcast.net/~peter.m.brown/gr/grav_red_shift.htm

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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #15 on: 06/10/2013 23:49:27 »
There must also be a separation between light and momentum giving the fixed speed. Momentum is a constant rather than a variable. If momentum is a property of matter then there is no rest frame. The contraction of receding galaxies could actually be stretching the spaces in between. This may mean this intergalactic space is length expanded and in effect speeds up.

Jeff - May I make a suggestion? There is a modify selection which allows you to modify a post that you've already made. Writing everything in a single post rather in a serious of multiple posts can make things easier to follow for some people, such as myself. :) This is simply a suggestion, nothing more.

My apologies I had a whole lot of ideas all at once and just wanted to get then out.
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #16 on: 06/10/2013 23:51:26 »
If an object is orbiting a black hole, it will radiate gravity waves, first circularising the orbit, then shrinking the orbit.

A Nobel Prize was awarded for detecting this effect in orbiting neutron stars. The same effect is expected to occur for objects orbiting a black hole.

There are very few characteristics of a black hole that are thought to be observable outside the black hole: Its mass, electrical charge and angular momentum.

See: http://en.wikipedia.org/wiki/Kerr%E2%80%93Newman_metric

Yes I already knew about the mass, charge and angular momentum and information loss paradox. Thanks for the info on gravitational waves.
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #17 on: 06/10/2013 23:56:40 »
Quote from: jeffreyH
Does time dilation effect the matter below the surface of a spherical mass. We know on the surface it does but does the interior?
Yes. Gravitational time dilation is a function of the gravitational potetial and below the surface of a gravitating body there is also a gravitational potential. The difference in clock rates is caused by a difference in the value of gravitational potential.

BTW time dilation is the same phenomena as gravitational redshift so expect people to use the terms interchangebly. See http://home.comcast.net/~peter.m.brown/gr/grav_red_shift.htm

Surely then gravity itself must be dilated. If you jump in an intense gravitational field with respect to earth gravity your time dilation from an external frame would appear to make your motion slower. Hence from the outside observer's view gravitational momentum has slowed. This also implies that the gravitational speed during a collapse towards an event horizon would slow progressively. Has this been taken into account? If so what conclusions were reached.
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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #18 on: 07/10/2013 00:47:37 »
Quote from: jeffreyH
My apologies I had a whole lot of ideas all at once and just wanted to get then out.
I understand. It's my experience that when a poster creates a string of seperate posts it can be irritating to others.

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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #19 on: 07/10/2013 00:50:45 »
Quote from: jeffreyH
Surely then gravity itself must be dilated. If you jump in an intense gravitational field with respect to earth gravity your time dilation from an external frame would appear to make your motion slower. Hence from the outside observer's view gravitational momentum has slowed. This also implies that the gravitational speed during a collapse towards an event horizon would slow progressively. Has this been taken into account? If so what conclusions were reached.
Yes. Absolutely. This is very well known. When a star starts to implode the matter slows down as it reaches the Schwarzchild radius and never passes the event horizon. That’s why they used to refer to black holes as frozen stars.

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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #20 on: 07/10/2013 01:41:25 »
Quote from: jeffreyH
Surely then gravity itself must be dilated. If you jump in an intense gravitational field with respect to earth gravity your time dilation from an external frame would appear to make your motion slower. Hence from the outside observer's view gravitational momentum has slowed. This also implies that the gravitational speed during a collapse towards an event horizon would slow progressively. Has this been taken into account? If so what conclusions were reached.
Yes. Absolutely. This is very well known. When a star starts to implode the matter slows down as it reaches the Schwarzchild radius and never passes the event horizon. That’s why they used to refer to black holes as frozen stars.

I am so glad someone has confirmed that. I thought I was raging against the conventional wisdom.
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Re: Theoretically, how does gravity behave inside a black hole
« Reply #21 on: 07/10/2013 01:53:08 »
Quote from: jeffreyH
I am so glad someone has confirmed that. I thought I was raging against the conventional wisdom.
Please do me a great favor. Never give up an idea merely because it seems like you're going against conventional wisdom, okay? :)

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lean bean

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #22 on: 07/10/2013 19:14:10 »
I can't see there being enough gravitational field strength from this matter.

Enough field strength for what ?

Quote
In fact any accelerating mass will emit gravitational waves in much the same way as an accelerating charged particle emits electromagnetic radiation. Even as you move your hand and mouse to read this web page your movements emit very weak gravitational waves. These gravitational waves are similar to light and radio waves in many respects and carry energy from their sources.
From https://www.astro.cf.ac.uk/research/gravity/tutorial/?page=1blackholes

I am so glad someone has confirmed that. I thought I was raging against the conventional wisdom.

I think the 'conventional wisdom' is...  in the infalling matter's frame it crosses the horizon, but from the distant observer's frame the infalling matter never reaches the horizon.

Yes. Absolutely. This is very well known. When a star starts to implode the matter slows down as it reaches the Schwarzchild radius and never passes the event horizon. That’s why they used to refer to black holes as frozen stars.

Pete, should that be...the matter never passes the horizon as seen by a distant observer?  But from the infalling matter's frame it does cross the horizon.


« Last Edit: 07/10/2013 19:28:36 by lean bean »

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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #23 on: 07/10/2013 19:22:25 »
Quote from: lean bean
Pete, should that be...the matter never passes the horizon as seen by a distant observer?  But from the infalling matter's frame it does cross the horizon.
Yes. My appologies if I didn't make that clear.

This applies to observers outside the event horizon. Why they call them "distant" is beyond me. They could be very close in fact.

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lean bean

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #24 on: 07/10/2013 19:32:02 »
Quote from: lean bean
Pete, should that be...the matter never passes the horizon as seen by a distant observer?  But from the infalling matter's frame it does cross the horizon.
Yes. My appologies if I didn't make that clear.

This applies to observers outside the event horizon. Why they call them "distant" is beyond me. They could be very close in fact.
Dam, you answered whilst I was modifying my post.  :) :)


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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #25 on: 07/10/2013 21:02:01 »
Quote from: lean bean
Pete, should that be...the matter never passes the horizon as seen by a distant observer?  But from the infalling matter's frame it does cross the horizon.
Yes. My appologies if I didn't make that clear.

This applies to observers outside the event horizon. Why they call them "distant" is beyond me. They could be very close in fact.
Dam, you answered whilst I was modifying my post.  :) :)

That is only theoretical. It could take an infinite time for the mass to collapse inside the radius.
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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #26 on: 08/10/2013 03:58:32 »
Quote from: jeffreyH
That is only theoretical. It could take an infinite time for the mass to collapse inside the radius.
Why would you say "That is only theoretical"? It gives the impression that other things we accept as fact aren't really "only theoretical" such as the expansion of the universe.

I use that phrase "only theoretical" very rarely myself. I recommend that you do the same. It's not a useful statement to make. Everything in science is really theoretical if you want to be exact.

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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #27 on: 08/10/2013 04:12:56 »
Quote from: jeffreyH
That is only theoretical. It could take an infinite time for the mass to collapse inside the radius.
Why would you say "That is only theoretical"? It gives the impression that other things we accept as fact aren't really "only theoretical" such as the expansion of the universe.

I use that phrase "only theoretical" very rarely myself. I recommend that you do the same. It's not a useful statement to make. Everything in science is really theoretical if you want to be exact.

Sorry a better phrasing would be it is only one theory and there could be competing theories that demonstrate equally valid hypotheses.
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Re: Theoretically, how does gravity behave inside a black hole
« Reply #28 on: 08/10/2013 04:25:53 »
Quote from: jeffreyH
Sorry a better phrasing would be it is only one theory and there could be competing theories that demonstrate equally valid hypotheses.
You could say that everytime general relativity comes up. Is that a road you really want to go down?

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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #29 on: 08/10/2013 04:27:22 »
I can't see there being enough gravitational field strength from this matter.

Enough field strength for what ?

Sorry I didn't answer this sooner. I don't think the mass leaving the accretion disk would produce the required gravitation as there probably wouldn't be enough. However the momentum and a compression factor may come into play. I am very unsure about any of this.
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #30 on: 08/10/2013 04:29:17 »
Quote from: jeffreyH
Sorry a better phrasing would be it is only one theory and there could be competing theories that demonstrate equally valid hypotheses.
You could say that everytime general relativity comes up. Is that a road you really want to go down?
[/quote

Pete at this point in time I can hardly see the actual road never mind find the direction. I am in a bit of a quantum fluctuation. :-)
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Re: Theoretically, how does gravity behave inside a black hole
« Reply #31 on: 08/10/2013 04:44:52 »
Quote from: jeffreyH
Pete at this point in time I can hardly see the actual road never mind find the direction. I am in a bit of a quantum fluctuation. :-)
In that case here is a chapter on the philosophy of science that I recommend reading - http://home.comcast.net/~peter.m.brown/ref/philosophy_physics.pdf
« Last Edit: 08/10/2013 04:51:52 by Pmb »

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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #32 on: 08/10/2013 06:51:09 »
Quote from: jeffreyH
Pete at this point in time I can hardly see the actual road never mind find the direction. I am in a bit of a quantum fluctuation. :-)
In that case here is a chapter on the philosophy of science that I recommend reading - http://home.comcast.net/~peter.m.brown/ref/philosophy_physics.pdf

OK There may be theories that not only account for relativistic effects but add new laws that expand on it.
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lean bean

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #33 on: 08/10/2013 16:42:40 »
I don't think the mass leaving the accretion disk would produce the required gravitation as there probably wouldn't be enough. However the momentum and a compression factor may come into play. I am very unsure about any of this.
Jeff,  just moving your hand emits gravitational waves (very weak ones).
It's in the link I gave earlier...
Quote
In fact any accelerating mass will emit gravitational waves in much the same way as an accelerating charged particle emits electromagnetic radiation. Even as you move your hand and mouse to read this web page your movements emit very weak gravitational waves.
My bold. From https://www.astro.cf.ac.uk/research/gravity/tutorial/?page=1blackholes
But, now I guessing you may mean by 'enough' ...enough for detection??




 

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Offline Pmb

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #34 on: 09/10/2013 03:17:43 »
Let's make it clear what generates waves, both electromagnetic and gravitational.

Suppose there is a distribution of matter in a region of space Q and you measure the field (electromagnetic or gravitational as the case may be) at a location r. Now change the matter which generates the field. If the field remains unchanged at all r then no radiation will be produced. Simple, huh? :)

E.g. consider a spherically symmetric ball of charge. If you have the same ball but rotated about an axis of symmetry then the field the charge generates will remain unchanged, even though charge was moved. Note that I do not mean that one actually rotates the ball since that would actually generate an electric field because during the rotation charges would be in motion and that would create a magnetic field and this would generate an EM wave.

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lean bean

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Re: Theoretically, how does gravity behave inside a black hole
« Reply #35 on: 09/10/2013 19:59:52 »
Pete
 I agree that a symmetrical rotating sphere would not produce gravitational waves.
But, I'm not following you in this part...
Suppose there is a distribution of matter in a region of space Q and you measure the field (electromagnetic or gravitational as the case may be) at a location r. Now change the matter which generates the field. If the field remains unchanged at all r then no radiation will be produced.
By accelerating the matter you are producing gravitational waves locally.
  That the waves may not be detected farther away is down to the waves losing energy through interacting with ‘matter’ along the way, and not down to no gravitational waves being produced at all.
I take the waves to be ‘disturbances’ in the gravitational field.
 Didn’t the book ’Exploring Black Holes’ describe them as ’travelling tidal accelerations’, something like that. :)
« Last Edit: 09/10/2013 20:04:10 by lean bean »

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Offline syhprum

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Re: Theoretically, how does gravity behave inside a black hole?
« Reply #36 on: 09/10/2013 22:39:40 »
I believe there is nothing magical about black holes once we have passed thru the event horizon which should be quite un-traumatic for a large BH we will see a high density but nowhere infinite density object before us and we will gravitate towards it in the normal Newtonian manner.
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Online jeffreyH

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Re: Theoretically, how does gravity behave inside a black hole?
« Reply #37 on: 09/10/2013 23:42:55 »
I believe there is nothing magical about black holes once we have passed thru the event horizon which should be quite un-traumatic for a large BH we will see a high density but nowhere infinite density object before us and we will gravitate towards it in the normal Newtonian manner.

It all comes down to the c in e=mc^2. A combination of length and momentum. Einstein got just about all of it right but made the mistake of looking for a unified field theory when in fact he already had it.
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