Centre of the universe

  • Thread starter Viper
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  • #1
Viper
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In the centre of the universe I belive there is a giant black hole that all galaxies orbit
 

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  • #2
KLscilevothma
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the universe doesn't have a centre
 
  • #3
Viper
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But then if you look at all of the galaxies they are swirled around a centre or central area or an object(s) of intebse gravity
 
  • #4
chroot
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Originally posted by Viper
But then if you look at all of the galaxies they are swirled around a centre or central area or an object(s) of intebse gravity
Wrong.

- Warren
 
  • #5
KLscilevothma
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I don't think galaxies are swirled around a centre, rather they are moving away from us. That's why we say the universe is expanding.
 
  • #6
Viper
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Ok but what are they stretching from. If the universe becomes too stretshed will there be like an elastic affect?
 
  • #7
chroot
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Originally posted by Viper
Ok but what are they stretching from. If the universe becomes too stretshed will there be like an elastic affect?
What are they "stretching from?" Can you please try to be a little more clear?

- Warren
 
  • #8
KLscilevothma
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the fate of the universe depends on the amount of matter inside it.

There are 3 types of universe, closed universe, open universe and critical universe.

A close universe ends up with a big crunch(the universe collpases) while an open universe ends up with a big freeze (the universe stop expanding)

Our universe is a critical universe, which has a flat curvature. So it won't end up with a Big Crunch or a Big Freeze.

(I'm not very sure about the recent developments of astronomy, scientists still think our universe is a flat one, right? )
 
  • #9
Loren Booda
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The universe may itself be considered a black hole, which from our perspective has potential centers everywhere within. Its centers are isotropic from every homogeneous point to their event horizons where the escape velocity exceeds the velocity of light relative to the observer.
 
  • #10
Viper
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Thats more like it
 
  • #11
Phobos
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The universe has no center or edge in 3D space. The universe is boundless. The overall expansion of the universe is essentially omni-directional (occurs in all directions from every point). Things only appear to be moving away from us because we are only viewing from one reference point. If you were to observe from another distant galaxy, things (including the Milky Way) would appear to be moving away from that point too.

Not all galaxies have a massive center. There are many elliptical/irregular shaped galaxies that are without massive/easily-to-define centers like our own. Photos one sees in the media are usually spiral galaxies because they are so picturesque.

Stretched space is not expected to snap back. It will continue to expand forever...probably at an accelerating pace.

Yes, the universe is still considered "flat" as far as I know. That means it will expand forever. An open universe will expand forever too. The "big freeze" mentioned does not refer to stopped expansion, but rather "heat death" in which all matter falls apart and all energy is reduced to ground state....the universe is left as a cold, thin soup of fundamental particles with no useful energy.

Although Loren's post makes for an interesting discussion, I think it's confusing Viper's topic. By definition, a black hole is an object residing within spacetime, not the whole of spacetime itself. But the similiarities are worth a separate topic of discussion.
 
  • #12
M. Gaspar
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Evaporating Black Holes? I don't think so.

Has anyone logged the "death" or "disappearance" of a black hole.

What could STOP a black hole from "eating" its "neighborhood"?

I don't buy Hawkings thought that because some energy radiates OUT that a black hole will eventually "evaporate". More stuff goes in; it becomes more massive; its gravity increases; it eats more stuff.

If black holes continue forming -- and consuming matter/energy -- then doesn't it follow that EVENTUALLY black holes will suck in everything in between, until they all "unite" into a singularity (AGAIN!)?

There's your "Big Crunch"...and a brief look at the "life cycle" of the Universe...an Eternal Entity of Energy that reincarnates from Big Bang to Big Bang.
 
  • #13
Jack
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Originally posted by Viper
But then if you look at all of the galaxies they are swirled around a centre or central area or an object(s) of intebse gravity

The unviverse has no centre because it is not expanding from a single point like an explosion but rather every bit of space increases in size and then that it turn increases in size. The galaxies are not centred around a 'central area' (as far as we know).
 
  • #14
Mr. Robin Parsons
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re Black holes

Originally posted by M. Gaspar

I don't buy Hawkings thought that because some energy radiates OUT that a black hole will eventually "evaporate". More stuff goes in; it becomes more massive; its gravity increases; it eats more stuff.

As I recollect Hawkings work, the radiation is not from the center of the Black Hole, but from the interaction of the 'event horizon' with the 'fabric' of space/time.

The Black Hole itself radiates nothing! (loses no mass)

A Black Hole does NOT "eat it's neighbourhood" as it is a gravitational well that only increases in size relative to the mass within it, so it is NOT like a vacuum cleaner sucking up everything around it, it simply empties the space around it to a decreed limitation that is imposed by the Modus Operandi of Gravity.

After that, it is up to the mass to get close enough for the gravity to take hold and effect it, suck it in.
 
  • #15
M. Gaspar
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Here comes the Crunch!

And matter will cooperate over time.
 
  • #16
Brad_Ad23
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yes it will over time. But, eventually you run out of matter, and the black hole will evaporate. This is why it is generally said that stellar sized black hole has a lifetime of about a googol years (the bigger the hole, the much longer it takes).
 
  • #17
M. Gaspar
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Brad...

Perhaps you "run out of matter" because it all gets compressed into a singularity -- down the road! -- from whence springs the next "Big Bang".
 
  • #18
Brad_Ad23
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I should point out to you that all the black holes that form will NOT colesce into one giant one. The universe will be expanding so fast that far in the future, that it'd be lucky if a black hole was within the present diameter of the universe from another black hole. And as was pointed out, black holes merely empty the space surrounding them.

That means if the sun suddenly was replaced by a black hole of equal mass, all objects would continue to orbit the black hole as they presently do...exception being Mecruy due to its proximity, but even then it is doubtful it would be pulled in.
 
  • #19
Mr. Robin Parsons
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Err, Uhmmm, a Correction? sorta...

Originally posted by Brad_Ad23

And as was pointed out, black holes merely empty the space surrounding them.

That is quite true for the Short ranging of gravities ability, but , Gravity is presently thought of as having Infinite range, till that is proven differently, we must accept, that given enough time Gravity will win out over everything else, and all will be drawn back together into a, well, whatever is the center of a Black Hole, presently thought of as a singularity.

It's the Newtonian thing, M + M / D2
 
  • #20
Brad_Ad23
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Well all things equal that is correct. However, there is that rather odd acceleration to the expansion of the universe that pretty much seals the universe's fate as the heat death.

And yes gravity has infinite range...but does that mean the gravity has the same strength? Nope. If matter is traveling sufficiently fast enough (as it would be) and if space is expanding fast enough (as it would be) then the matter will just keep on going until eventually it runs into whatever black hole it may encounter, if any.
 
  • #21
M. Gaspar
679
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Lucky Universe

Brad...

Per your posting... then I think the Universe is going to "get lucky" because, even though it may be expanding at an accelerating rate, this does not preclude an eventual deceleration...especially if there is a relentless and irresistable attractive force pulling It in.

Perhaps I'm obtuse and hopelessly uninformed, but why do physicists -- at the moment --"believe" that a black hole -- the result, itself of an imploded matter/energy -- is not "pulling things in" but instead, everything just gets "stuck" at the "event horizon".

Because of some mathematical construct that will DE-struct in the future?

And why does Hawkings think that black holes will "evaporate"?

I might be left-brain-dead, but my right brain tells me something is amiss with current "theories".

Has anyone run computer models on the pull of current -- and future additional -- black holes on the rest of the Universe over time?

And why is this "important" to me? Because I like my own belief system which has the Universe as a living, conscious Entity that expands and contracts from one incarnation to the next.

I might be wrong, but I'm having a lot of fun with my speculations.

AND, I might be right.
 
  • #22
Brad_Ad23
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Ah misconceptions.

Gravity is a very weak force. The strength it has occurs only near the event horizon. Think of a very severe local curvature of spacetime. Far away it is like any other body of the same mass, but very near it becomes strong. So gravity quite simply is losing the battle here.

The matter does not get stuck at the event horizon. It only seems that way to an outside observer, but it does very much pass through the event horizon.
 
  • #23
Mr. Robin Parsons
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Event horizon

Gravity at the 'event' horizon is only called that because at that particular event horizon NOTHING escapes it, including light.

For most gravitational bodies there is no real, or apparent, 'event horizon' as the vast majority cannot preclude the escaping of light.

As for this idea of continuous expansion "forever", given that the gravitational force will be forever 'braking' that expansionary force, doing the math would tell you that, 'eventually', gravity will be able to stop any object travelling away from the gravitational source, and 'eventually', reverse it's direction, till it begins to return towards the gravitational generator.

It may appear as weak, but it is inccessant!
(persistance wins!)
 
  • #24
Viper
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How big is the event horizon?
 
  • #25
Mr. Robin Parsons
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It's relative..........

The event horizon is relatively sized to what is seen as the amount of mass that the Black Hole is 'theorized' to contain.

There is a sort of difficulty is measuring large stellar bodies as we do not have an adequate scale/balance for the task. Hence we end up with things like, we know the weight of the earth because we know how strong it's gravitational field is, and we know how strong the eath's gravitational field is, because we know how much it weighs.

Self supporting, ergo sorta 'unsupported' but accepted in general principal, and theory, cause we have no other means to test it
 
  • #26
Brad_Ad23
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Have you ever heard of escape velocity?

If you have a velocity greater than an escape velocity gravity will never return you to the body you came from. Hence why you need escape velocity to go anywhere outside earth orbit. The expansion drives things faster than the escape velocity of anything.
 
  • #27
M. Gaspar
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Yes, you can ESCAPE velocity!

Brad...

My view is that you -- and many others -- are thinking SMALL SCALE and SHORT TERM.

Please read above post of Mr. Robert Parsons. He used the words "incessant" and "persistence" while I used the words "relentless" and "irresistable" to describe an ATTRACTIVE process that is in for the LONG HAUL!


Thanks, R.P., I needed that.
 
  • #28
Brad_Ad23
502
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No, you didn't. Escape velocity applies to any gravitational system on any scale. Once the expansion of spacetime reaches a rate such that it is greater than what the gravitational force is, it will only get faster, further diminishing the gravitational force, until it is all but zero as everything will be isolated within its own event horizon (many trillions of years down the road). It just goes to fast for gravity to overcome. The same way if you launch a rock up out of earth orbit at about 11.6 km/s it will never come back to earth.
 
  • #29
M. Gaspar
679
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Enough is Enough

And I say there is ENOUGH gravity -- via the ultimate coallescing of black holes -- to do the trick.


And on another subject (should I start a thread?), would someone tell me what comes to mind when I say "OFF/ON" as it related to the workings of computers...and also to electromagnetism.

Keep it simple. I'm stupid.
 
  • #30
Brad_Ad23
502
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And the entire scientific community says otherwise. Black holes are severe local distortions of spacetime. If we have a black hole of Mass 5 then from far away it has the same effects as any other objec tof mass 5. However very near it, it is easy to see the black hole is worse. They are for lack of a better word, the whirlpools of spacetime.
 
  • #31
M. Gaspar
679
1
Down the Drain...

Thanks, Brad, for making my point.

I don't care what the "entire scientific community" is currently espousing. At least my speculations are being rejected by the best minds in the business!
 
  • #32
Brad_Ad23
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The difference is, they have the math to back them up..and it is rather elementary math at that. You have a flawed understanding of a black hole to go on. And...you ideas would most likely be rejected by any mind in the business heh.
 
  • #33
M. Gaspar
679
1
I can't argue with an equation...

So, I'll get back to you on this after a bit of research which might yeild me a few "business PARTNERS"...if you know what I mean.


Purely curious: Have there EVER been mathematical "PROOFS" that have eventually been "proven" to be false?

What if something vital is omitted from an equation?

I'm not baiting you. I really want to know.
 
  • #34
Brad_Ad23
502
1
Well anyone can come up with a mathematical 'proof' that is false.

ex.

2+2= 5, therefore 1+3 = 5, therefore 1+2 = 4. Prooved.

However in the real sense I can't recall any proofs that have been shown to be false merely because proofs require such stringent circumstances. Theories and theorems sure.

However in this case, the physics is very solid and elementary. The expansion of the universe is such that any two points in space that are not gravitationally bound (there's the key...galaxies and clusters for now will remain together), will have the space between them increase such that the velocity of the seperation between them is far greater than the escape velocity of either body. Once you are above escape velocity, you can escape that massive body.
 
  • #35
M. Gaspar
679
1
Thanks

Processing...
 

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