# The Naked Scientists Forum

### Author Topic: What is the shape of the largest possible object in universe ?  (Read 8896 times)

#### SmartK8

• First timers
• Posts: 6
##### What is the shape of the largest possible object in universe ?
« on: 06/12/2009 13:32:16 »
Hi, I always wondered..

What is an ideal shape of the largest (hypothetical) possible object in the universe ?

There are some conditions:

1) it can't collapse to a sun or a blackhole under it's own gravity (so, no sphere obviously)
2) it has to be connected all over its body (connection is defined as such, it can't violate 3)
3) it has to be act as a one object (as for example human body)
4) it has to be made from matter

So I'm asking about ideal distribution of mass without collapsing on itself.

regards,
Kate
« Last Edit: 25/01/2010 12:49:09 by chris »

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #1 on: 06/12/2009 13:45:31 »
Hi, I always wondered..

What is an ideal shape of the largest (hypothetical) possible object in the universe ?

There are some conditions:

1) it can't collapse to a sun or a blackhole under it's own gravity (so, no sphere obviously)
2) it has to be connected all over its body (connection is defined as such, it can't violate 3)
3) it has to be act as a one object (as for example human body)
4) it has to be made from matter

So I'm asking about ideal distribution of mass without collapsing on itself.

regards,
Kate

What is the largest object... well... it could theoretically be a black hole, but it's not quite an object in my eyes. More like an exotic hole.

#### SmartK8

• First timers
• Posts: 6
##### Re: What is the shape of the largest possible object in universe ?
« Reply #2 on: 06/12/2009 13:52:56 »
Hi, it violates point 1 (it's a blackhole) and 4) (it's elementary particles only).

If it wasn't obvious I don't want the largest object in the universe.

To clarify, basically I'm asking what is a shape of the largest construction possible.
Don't care about possibility of making it now.. just hypothetically.

For example:

If I start building a large sphere it will sooner, or later (from certain gravity) collapse to a gas like planet, sun, blackhole or whatnot. So you can't do that. You have to distribute it in space. And I'm asking what is the ideal distribution (or largest possible) while still being a "standard" (imagine large space station for example) construction.

regards,
Kate

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #3 on: 06/12/2009 14:03:38 »
Shape... well in that case, if the universe has an outside to it, like a superdimensional bulk, then the universe is the largest self-contained object in the multiverse. The universe would be itself an object floating in this superstring spacetime.. and there are three or possibly four different shapes the universe can take.
« Last Edit: 06/12/2009 14:06:00 by Mr. Scientist »

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #4 on: 06/12/2009 14:05:08 »
Space probably has some kind of shape.. the there is the saddle-shape for instance. According to the math, if Omega is found less than 1, then it has a negative curvature and so will have a shape like a saddle. According to the geometry of this universe, parallel lines do not meet and the interior angles of the triangles sum up to less than 180 degrees. There are three distinct existences, open, (the one which has a saddle-shape). Open just means that the universe will continue to expand so:

The evolution of the universe depends on three mathematical states.

If Omega is is equal to 1, then it will be flat and expand forever (1). And if Omega is less than 1, then it will result in a big freeze. But if Omega is greater than 1, then it will experience a gravitational collapse.

(1) - all observational evidence points to expanding forever unless effected by a big rip.

#### SmartK8

• First timers
• Posts: 6
##### Re: What is the shape of the largest possible object in universe ?
« Reply #5 on: 06/12/2009 14:13:01 »
Hi, thanks for the responses, but still it's not it.

To clarify more, I'll try to convert it to a different angle. Imagine you're building a space-station and from a certain point, its own gravity will make it collapse on itself. What I'm asking is what is the shape of space-station that won't collapse on it's own, while all the parts of this station are accessible without going space-walk.

Reasoning behind this question is:

If humans will be able to make themselves machines. You can upgrade your robotic body and make it larger and more powerful. But from a certain point (mass) it will collapse on itself. I want to avoid that, but what is the shape (while still having control over this robotic body) of this. All I know is that sphere is not the way to go. Possibly a disc (my friend suggested). I hope it's clear now.

1) universe
2) spherical object
3) naturally occurring object

regards,
Kate
« Last Edit: 06/12/2009 14:16:53 by SmartK8 »

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #6 on: 06/12/2009 15:03:27 »
Sorry Kate, i still can't make this out. Probably just me. :)

#### SmartK8

• First timers
• Posts: 6
##### Re: What is the shape of the largest possible object in universe ?
« Reply #7 on: 06/12/2009 16:23:53 »
Well, I said it all, there's no easier way to describe that. I admit that's a tough one. Hopefully someone else will have an idea.

regards,
Kate

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #8 on: 06/12/2009 17:00:01 »
I hope someone else can attend to your questions too :)

#### JP

• Neilep Level Member
• Posts: 3366
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #9 on: 06/12/2009 19:00:31 »
It seems that what you're basically asking is how large you can make a solid object so that the primary force holding its molecules together are is electromagnetism rather than gravity.

An infinite object wouldn't collapse since every bit of the object would be getting pulled equally in all directions, so the gravitational forces at any point would cancel out.

I think a rotating disk might be good too, since gravity would contribute to centripetal forces instead of crushing the object.

#### SmartK8

• First timers
• Posts: 6
##### Re: What is the shape of the largest possible object in universe ?
« Reply #10 on: 06/12/2009 20:28:57 »
Rotating disc is good (rotating cylinder will be better, in this line of thinking), but I'm still not sure if it's an ideal shape. Moreover it's moving, I'd prefer a static object with the lowest volume possible. Maybe I'll run some genetic algorithm simulation. I still think it's some kind of complex network shape. It also has to be robust enough, not to collapse while expanding. I thought this would be a known thing, like that Dyson sphere or something.

About that infinite object.. I guess it would be the best, but the universe has the finite resources, so I can't count this one in.

regards,
Kate

#### LeeE

• Neilep Level Member
• Posts: 3382
##### Re: What is the shape of the largest possible object in universe ?
« Reply #11 on: 07/12/2009 01:52:16 »
The largest shape of anything in the universe can only be described as 'everything'.

Are you thinking about Tipler Cylinders?

http://en.wikipedia.org/wiki/Tipler_cylinder

#### Mr. Scientist

• Neilep Level Member
• Posts: 1451
• Thanked: 2 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #12 on: 07/12/2009 03:05:08 »
Ah... the Tipler Cylinder... Impossible to create but ingeneous.

#### Democritus

• Jr. Member
• Posts: 44
##### Re: What is the shape of the largest possible object in universe ?
« Reply #13 on: 12/12/2009 06:39:57 »
Hi Kate
I think I know what you're driving at, and I'll answer as if I do, and see if that helps.
Triangles are stable shapes in two dimensions and pyramids are stable constructs in three dimensions.

I'm thinking that one of the polyhedrons, good pics at
http://en.wikipedia.org/wiki/Regular_polyhedron [nofollow]
would offer opportunities as your base fractal unit of construction.

"A fractal is an object or quantity that displays self-similarity, in a somewhat technical sense, on all scales. The object need not exhibit exactly the same structure at all scales, but the same "type" of structures must appear on all scales." This definition is from
http://mathworld.wolfram.com/Fractal.html [nofollow]
where there are  pics of the fractal concept in two dimensions.
But imagine three dimensional fractally self-replicating tetrahedrons self-organising into connected nodes to avoid localised destructive gravity wells.

That might work. Give it a go Kate, today the world...tomorrow, the Universe!!
Best wishes
Democritus
(btw, if you want to check out the grandaddiest fractal of them all, search for The Mandelbrot Set. D)

• Neilep Level Member
• Posts: 1451
##### Re: What is the shape of the largest possible object in universe ?
« Reply #14 on: 12/12/2009 13:22:48 »
Well, after you've reached the size limit of your station, build a bridge from that to a far enough distance away and then start building more station.

#### owenlove

• First timers
• Posts: 1
##### Re: What is the shape of the largest possible object in universe ?
« Reply #15 on: 14/12/2009 09:05:29 »
Well i guess ..sphere

#### Geezer

• Neilep Level Member
• Posts: 8328
• "Vive la résistance!"
##### Re: What is the shape of the largest possible object in universe ?
« Reply #16 on: 16/12/2009 02:12:34 »
Obviously, its the shape of your average galaxy.

I'm going to claim I didn't violate any of your conditions either!

#### yor_on

• Naked Science Forum GOD!
• Posts: 11720
• Thanked: 1 times
• (Ah, yes:) *a table is always good to hide under*
##### Re: What is the shape of the largest possible object in universe ?
« Reply #17 on: 26/12/2009 02:01:55 »
Why not a spiral or a cylinder or a 'U', as long as it is in deep (outer) space there is very little restricting the way you want to build something. To build it flatly is to use both sides and if you can find some way to put it aside itself you might even get gravitational forces working on it. You didn't specify if one should be able to live on it though?

#### neilep

• Withdrawnmist
• Naked Science Forum GOD!
• Posts: 20602
• Thanked: 8 times
##### Re: What is the shape of the largest possible object in universe ?
« Reply #18 on: 26/12/2009 02:08:35 »
How about a Dyson Sphere ! ?..it's like....well big !

http://en.wikipedia.org/wiki/Dyson_sphere

#### Geezer

• Neilep Level Member
• Posts: 8328
• "Vive la résistance!"
##### Re: What is the shape of the largest possible object in universe ?
« Reply #19 on: 26/12/2009 02:32:14 »
How about a Dyson Sphere ! ?..it's like....well big !

http://en.wikipedia.org/wiki/Dyson_sphere

Oh yes! That's the big thing that bloke Dyson sticks on his Hoovers instead of wheels.

#### yor_on

• Naked Science Forum GOD!
• Posts: 11720
• Thanked: 1 times
• (Ah, yes:) *a table is always good to hide under*
##### Re: What is the shape of the largest possible object in universe ?
« Reply #20 on: 26/12/2009 14:27:35 »
Yeah Neilep, nice one.

#### SmartK8

• First timers
• Posts: 6
##### Re: What is the shape of the largest possible object in universe ?
« Reply #21 on: 25/01/2010 12:41:18 »
The point is to ideally use all the space so, I'll comment one by one:

LeeE: Tipler cylinder ? You can't build a body out if it. But definitely interesting.

Democritus: That might work, sounds like a winner. I guess there'd have to be some kind of granulation. I mean at smaller scales just usable space, while on the larger (some calculable ratio perhaps) the shape should be reinforced; I'll try to calculate the ideal shape of those, and also material requirements.

Madidus_Scientia: That'd work perhaps a diamond shape grid of such bridges, but it's not ideal use of space; I guess.

owenlove: Nope, would collapse on itself at a critical mass.

Geezer: Disc was our first shot too, but it's moving - I realized, which condition I added later (sorry).

yor_on: You don't need to live on it. You'll be it. In billion years or so :P . It just mustn't collapse on itself, and I guess a rotation is not favorable (only for the purposes of energy source - gravity).

neilep: Dyson sphere is good for retrieving enery from the sun. But not exactly ideal shape to cover the least volume of electronics (or whatever the equivalent will be) inside of you.

So I guess the Democritus topology space texturing is the answer.

Thanks, to all of you. I'll try some simulations, and be back when done.

#### LeeE

• Neilep Level Member
• Posts: 3382
##### What is the shape of the largest possible object in universe ?
« Reply #22 on: 26/01/2010 01:08:49 »
A hollow sphere of any size will not collapse, as long as the walls of the sphere are thin enough to ensure there's no local collapse.

#### Democritus

• Jr. Member
• Posts: 44
##### What is the shape of the largest possible object in universe ?
« Reply #23 on: 27/01/2010 06:54:20 »
My "fractally self-replicating tetrahedrons self-organising into connected nodes to avoid localised destructive gravity wells" will ultimately fail and collapse. Irregardless of the distance seperating connected nodes; ditto the localised and overall density of the construct (materials mass/volume); there will come a time in construction when the object will fail towards its centre of gravity. Just before that point you will have the largest/most massive object possible. Which  I would intuit would not be particulary large at universal scales.

Unless.
Consider construction to commence simultaneously at universal scales. That is, build it everwhere at once. Build it so that the dark energy component (tending to accelerate universal expansion) nicely balances local and universal  gravitation so that our object is not spaghettied nor crunched.

No rotation needed. All resources of the universe can be invested in the construction of the object. The object will supplant the universe. And surly be the largest possible.

Acquiring superluminal technology so that messages/information can be sent to all points of the universe with regard to the what, how and when of the construction. A mere detail, really.

Once constructed our object would be the Universe.
So the shape of the largest possible object in the universe would be fractally tetrahedral. Little pyramids as part of larger. Larger as part of huge. Etc.

Purpose of Object.
To provide a sharpening facility to the widest variety of razor blade sizes as possible.
Best wishes
D

#### LeeE

• Neilep Level Member
• Posts: 3382
##### What is the shape of the largest possible object in universe ?
« Reply #24 on: 27/01/2010 18:52:29 »
Hmm...  Just a thought re very large hollow spheres...

If the sphere is large enough, the space inside it would be subject to expansion, along with the rest of the universe, so would the sphere eventually burst?

#### The Naked Scientists Forum

##### What is the shape of the largest possible object in universe ?
« Reply #24 on: 27/01/2010 18:52:29 »