Dyson Sphere

[Grasshopper27]

Originally posted by: Astaroth33

Originally posted by: grasshopper26
The Earth is 26,000 miles thick actually.

Er, no.

According to NASA, the diameter of the Earth is as follows: 12756 Kilometers = 7,926.210928 Miles

The circumference of the Earth at the equator is approximately 25,000 miles.

Er, right.

Like I said, the Earth is 26,000 miles around the Equator.

Whatever, if the sphere was only 4,000 miles thick it would still have to be made up of 21,000 star systems (including their suns)

Even if it were only 40 miles thick you'd still need 210 star systems to build it. How close are we to being able to collect material from 210 star systems and bring it here?

For that matter, it could be 2,000ft thick (0.4 mile) and you'd still need 2 star systems worth of material to do it (including both suns).

Grasshopper

 

[Adul]

SO WHAT GRAVITY WILL SOMETHING THAT MASSIVE HAVE ON ITS OWN?

wouldu even need artificle gravity?

 

[Grasshopper27]

Originally posted by: Adul
SO WHAT GRAVITY WILL SOMETHING THAT MASSIVE HAVE ON ITS OWN?

wouldu even need artificle gravity?

Maybe not, I honestly don't know.

Grasshopper

 

[silverpig]

Obviously everyone missed my post about you probably getting crushed by the gravity of the thing...

 

[Kadarin]

Originally posted by: silverpig
Obviously everyone missed my post about you probably getting crushed by the gravity of the thing...

No, you wouldn't. While it's true that if you used, say, two solar systems to build the thing, it would have the mass of two solar systems, that mass would be distributed over a wide area. Gravitational effects wold be interesting, but you'd be attracted to mass that's closer to you, given that gravity follows the inverse square law. While a mathemetician could tell you for sure, my guess is that for an inhabitant of the inside of the sphere, there would be a natural gravitational field attracting that person to the inner surface. Given also that the sphere is not in orbit around the sun, there would be significant gravitational attraction towards the sun. I do not know which effect would be stronger.

 

[silverpig]

You're totally missing my point.


You have 40 000 miles of solid substrate beneath your feet. That's a whole heck of a lot of mass. The gravitational pull of that strength would suck you through the shower drain.

The sun's gravitational pull would be very very insignificant due to the fact that it'd be over 146 000 000 km away.


Now, there is one other possibility that I can think of. Let's say that the sphere is a total of D miles wide. You would be standing on a point inside the sphere at x = 40 000. You would have the mass of whatever portion of the mass of the sphere exists in the region of space:

S = {x, y, z E R | x^2 + y^2 + z^2 = D^2, D - 40 000 < x < D}

Parts of this mass would be very very close to you (in fact you will be touching some of it). However, it represents just a sliver of the total mass of the sphere. The rest of the mass exists in the region of space:

So = {x, y, z E R | x^2 + y^2 + z^2 = D^2, -D < x < D - 40 000}

This mass is much much greater than the previous one, but most of it is extremely far away from you. I'm too lazy to carry out the integration, but it may happen that the two effects will exactly cancel each other out (I know it does for a charged sphere with a charged particle inside of it).

 

[Howard]

This is solved by the internal shields which can be turned clear or opaque (they would be placed in the "sky" between the surface and the sun). Again, if you can build this, you have shield technology.

Er, no. Liquid crystals in LCDs can be continously aligned (to any degree) to allow (or prevent) light transmission.

 

[dethman]

just a random thought, in a dyson sphere, since the energy doesn't dissipate anywhere (i'm assuming it's not going to go through your hypothetical 40,000 miles thickness very quickly), wouldn't everything burn up eventually?

answer is probably on google somewhere...eh too lazy to search.

 

[Howard]

We could always cover all the line-of-sight area with solar panels and convert it to electricity.

 

[Grasshopper27]

Originally posted by: silverpig
You're totally missing my point.

You have 40 000 miles of solid substrate beneath your feet. That's a whole heck of a lot of mass. The gravitational pull of that strength would suck you through the shower drain.

Then maybe you need anti-gravity devices to cancel out part of the mass you're standing on? Or perhaps it could be built 4,000 miles thick instead of 40,000 miles thick.

Whatever, anyone who can bloody mine entire star systems for spare matter can figure this minor bit out.

Grasshopper

 

[Grasshopper27]

Originally posted by: Howard

This is solved by the internal shields which can be turned clear or opaque (they would be placed in the "sky" between the surface and the sun). Again, if you can build this, you have shield technology.

Er, no. Liquid crystals in LCDs can be continously aligned (to any degree) to allow (or prevent) light transmission.

That would work too, but LCDs would require a physical structure mounted above everyone's head. Shields would just be energy projected above everyone's head.

On top of that, shields could provide radiation protection that LCDs couldn't.

Grasshopper

 

[JeffreyLebowski]

Originally posted by: grasshopper26
Posted this in another thread, but went to so much work I wanted to give it its own thread.

A ring world would be possible within reason, a Dyson Sphere is not reasonable. The amount of matter required to build such a construct would require star harvesting for hundreds of light years in every direction. The shell would need to withstand forces beyond anything even our Sun has to deal with. It would need to be about 40,000 miles thick. Again, the amount of material required to build a shell twice as thick as the Earth is all the way around the Sun is hard to imagine.

There is currently enough matter in the Solar System (not counting our Sun) to build a sphere 10 feet thick. To build one 40,000 miles thick would require matter from 211,200 solor systems (counting their stars). If you have the ability to harvest 211,200 solor systems for matter, then you don't need a Dyson Sphere in the first place.

On the plus side, growing room would not be an issue for awhile. The interior surface area of the Dyson sphere exceeds the total surface area of Earth by a factor of just over half a billion. Since all the surface area would be as close or as far as the builders wanted (mountains or flat lands), all of the space would be habbitable. This means that we would have 2 to 3 billion times more liveable surface area than we do now.

Every man, woman, and child could be instantly given 25 million square miles of land (half the Earth's livable surface area) What you'd actually DO with 25 million square miles of land is another matter.

Grasshopper

OK, you're saying that the shell would need to be 40K thick in order to protect it from interstellar matter that might bombard it. Correct?

Everyone else is under the impression that they will have force fields and such to contain the atmosphere. Wouldn't it be more fessible to build the sphere or ring say 2-4 miles thick(for all the internal parts and what not) and use directed enrgy weapons and shields to deflect any hazardous material? This would save 1,000's of years on construction and materials. Say maybe the mass of four Jupiters and Saturns total for a ring a 1,000 miles wide.

 

[Hayabusa Rider]

Just make it out of neutronium for cryin out loud!

 

[Grasshopper27]

Originally posted by: JeffreyLebowski
OK, you're saying that the shell would need to be 40K thick in order to protect it from interstellar matter that might bombard it. Correct?

No, it would need to be that thick to withstand the stresses on the structure.

If it were just a few miles thick, it would rip itself apart very quickly, even if made out of carbon nanotubes (one of the strongest things we know about, and even we can't built them yet in any volume).

Perhaps some new material will be invented that will reduce this size, but I doubt you'll be able to build such a thing just a few miles thick, the forces placed it on it would rip a star in two.

You would need shields to protect the outer shell, but that is a minor, long term issue. For something of this size, the planet Earth could smash into the outer shell and only do minor damage to it.

Grasshopper

 

[Kadarin]

Originally posted by: dethman
just a random thought, in a dyson sphere, since the energy doesn't dissipate anywhere (i'm assuming it's not going to go through your hypothetical 40,000 miles thickness very quickly), wouldn't everything burn up eventually?

answer is probably on google somewhere...eh too lazy to search.

Part of the whole point of building the thing in the first place would be to provide a means to capture and use all that energy for other purposes, rather than having it uselessly radiated out into space.

 

[JeffreyLebowski]

Well seeing as how this will be quite a ways off, building techniques, and materials will be way beyond Carbon nano-tubes. Plus if we have force fields and shields, we should have SIFs(structural integrity fields) ala Star Trek, cause we would have to master interstellar flight to get materials. So combine our advanced building materials with SIFs and 2-4 mile thick shells aren't out of the question.

Also Dyson's original Sphere concept wasn't a solid ball. it was a web of lattice structures.

 

[Kadarin]

Originally posted by: Hayabusarider
Just make it out of neutronium for cryin out loud!

Heh.. doing that would require more than just a few star systems' worth of mass, even if you had a way to manufacture the stuff in quantity.

 

[Grasshopper27]

Originally posted by: JeffreyLebowski
Well seeing as how this will be quite a ways off, building techniques, and materials will be way beyond Carbon nano-tubes. Plus if we have force fields and shields, we should have SIFs(structural integrity fields) ala Star Trek, cause we would have to master interstellar flight to get materials. So combine our advanced building materials with SIFs and 2-4 mile thick shells aren't out of the question.

Also Dyson's original Sphere concept wasn't a solid ball. it was a web of lattice structures.

Yes, structural integrity fields are one option, so long as they never, EVER fail.

The results if they failed would be quite impressive...

No, Dyson's original idea was not for a solid ball, but wouldn't a solid ball be cool?

Grasshopper

 

[JeffreyLebowski]

Originally posted by: Astaroth33

Originally posted by: dethman
just a random thought, in a dyson sphere, since the energy doesn't dissipate anywhere (i'm assuming it's not going to go through your hypothetical 40,000 miles thickness very quickly), wouldn't everything burn up eventually?

answer is probably on google somewhere...eh too lazy to search.

Part of the whole point of building the thing in the first place would be to provide a means to capture and use all that energy for other purposes, rather than having it uselessly radiated out into space.

Only prob is the used energy will return as waste heat. Though it can be used, it is effectively doubling the energy inside the sphere because the star is still outputting more energy. One way would be to radiate the excess energy into space. The other would be to collect it and send it to off sphere colonies. This way colonies could be put anywhere, even outside of star systems, where solar energy is not as abundant.

 

[JeffreyLebowski]

Yes, structural integrity fields are one option, so long as they never, EVER fail.

The results if they failed would be quite impressive...

No, Dyson's original idea was not for a solid ball, but wouldn't a solid ball be cool?

Grasshopper

I'd buy tickets.

 

[JeffreyLebowski]

For those that maybe are to lazy to search for it. Dyson sphere FAQ

i don't know how acurate this one is