Does big rip have an acceleration gradient?

[tommac]

Being spaghettified and being big-ripped would be quite different ways to go. One is mono-directional; the other is omni-directional.

How is spaghettification one directional? The whole point of spaghettification is that it is omni-directional. Think about it.

You have a bh ... as you FREE FALL into the black hole, you are semi weightless, however as you get closer there is a difference in the pull, a gradient persey. So that you feer ( if you are falling feet first, are pulled faster than your head. The net effect that you notice is that your feet are being pulled away from your head ... or your head is being pulled away from your feet ...

the force is:
<-H..T->

That is in the one direction ... BUT there is also something else that is going on, since there is a sphere of spacetime being collapsed into a circle ... the angle forces push inwards laterally. Like this

->h<-
->.-<
->t<-

this is what I am calling fan in.

The best illustration I have seen of this is in black holes and time warps by thorne, page 104 in my book under the sub topic tidal gravity and spacetime curvature

Note: if you were falling straight down, OR if the BH is sooooo big that the there isnt much tidal forces, to the point that they could get ignored, then you would not have any lateral forces acting on the body. However for smaller black holes, the tidal forces are significant .. thus the spagettification

[tommac]

I drew something up quickly to show you what I was talking about:



http://www.spacetimeandtheuniverse.c...e-universe.jpg


Here you have 4 scenerios,
1) pancake-ification head toe acceleration compressing lateral acceleration expanding
2) spaghettification head toe acceleration accelerating lateral acceleration compressing
3) pea-ification ( pointification ) head toe acceleration compressing lateral acceleration compressing
4) elephantification head toe acceleration expanding lateral acceleration expanding

For #2 we have the BH ...
For #4 we have an expanding universe
#1 and #3 I am not sure .... I guess for #1 it would something like a negative mass black hole where acceleration diminished with distance for #3 ... not sure ... but maybe a contracting universe.

Please let me know if I got this right.

[Andrew D]

Now since we fully agree on this part, the next part is to put the guy in an elevator, for some reason elevators are good for this stuff. Then another guy in an elevator that is falling into a black hole, and compare. Both will experience similar head to toe experiences ... where the head is pulled away from the toe, right? Do we agree here? Forget for a moment about the out the belly effect. But do you agree that the force in the head to toe is the same, assuming we calibrated our experiment?

No. The strength of the gravity field diminishes like 1/r^2 from head to toe, but the strength of cosmic expansion is, by definition, uniform.

[tommac]

No. The strength of the gravity field diminishes like 1/r^2 from head to toe, but the strength of cosmic expansion is, by definition, uniform.

Well again yes and no ... remember you are in freefall ... or we are comparing it with a free faller. So technically you are weightless ... EXCEPT ... EXCEPT for tidal forces. Those forces should be relatively uniform.

[cjl]

Well again yes and no ... remember you are in freefall ... or we are comparing it with a free faller. So technically you are weightless ... EXCEPT ... EXCEPT for tidal forces. Those forces should be relatively uniform.

Tidal forces are not uniform. They will cause a stretching in one direction and a compression in another. If you are considering a body which is not held together in any way, it will deform under the influence of tidal forces. The same object (completely unbound so the object's strength doesn't come into the equation) would stay the same shape under the influence of cosmic expansion. It would expand, yes, but not deform.

[WayneFrancis]

Now since we fully agree on this part, the next part is to put the guy in an elevator, for some reason elevators are good for this stuff. Then another guy in an elevator that is falling into a black hole, and compare. Both will experience similar head to toe experiences ... where the head is pulled away from the toe, right? Do we agree here? Forget for a moment about the out the belly effect. But do you agree that the force in the head to toe is the same, assuming we calibrated our experiment?

Don't you realise that what you've been saying is NOT the same as what the rest of us have been saying? So
Have you
A) Changed your point of view?
or
B) Totally hosed your initial description?

Seeing your initial description does describe a inverse spagettification process and that seems to be your arguement one would assume that you are now changing your point of view. If not...well then I don't think you've hosed your initial description, I believe it is what you meant to say so ... I'd say you still don't understand what anyone is telling you.

Read this
Expansion is NOT the reverse of falling into a black hole.

[WayneFrancis]

Hah ... that is because he is right.

Tommac you don't get it...Roobydo said the same thing I did.

[WayneFrancis]

Well again yes and no ... remember you are in freefall ... or we are comparing it with a free faller. So technically you are weightless ... EXCEPT ... EXCEPT for tidal forces. Those forces should be relatively uniform.

Freefall doesn't matter. Not a bit. An observer in free fall will still experience a 1/r² "gradient" of the gravitational force in the direction of free fall even if they don't "Feel" it. In cosmic expansion the observer will experience constant force in every direction.

1/r² != x

How many times do you have to be shown mathematically that an inverse square law rule is not the same thing as a constant rule?

[WayneFrancis]

Does anyone want to wager me that tommac comes back and still won't admit that his view of tidal forces and cosmic expansion are not related in the way he's implying.

I'll guess he'll keep telling us we don't get it, latch onto something we've said and distort it and claim that someone is in agreement with him when in actuallity no one is.

[PetersCreek]

I'll guess he'll keep telling us we don't get it, latch onto something we've said and distort it and claim that someone is in agreement with him when in actuallity no one is.

He may do that in the ATM forum in the process of defending a new theory. But arguing mainstream answers in the Q&A forum on ATM priciples? Nope.

Thread closed.