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Biggest void in space is 1B light years across (2007)

newscientist.com

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Re: Biggest void in space is 1B light years across (2007)

#71

Post by m4rtink »

ncmncm wrote: post #63
m4rtink wrote: post #35

Earlier quoted context omitted.

Unless you can harvest interstellar medium at scale stars are where most mass is locked up, conveniently in a single place even. Outer belt objects are quite small in volume in comparison and inconveniently far from each other.

The outer belt objects are small compared to planets, but are enormous considered as extracted volume, and uncountably numerous; whereas on inner planets you are effectively limited to the solidified skin at the bottom of an annoying gravity well, bathed in heat that must be shed. Kuiper belt distances are inconvenient only when you are in a hurry and have limited speeds. Given fusion propulsion, nothing inside a sol…

Good point - the exposed surface are for easy mining is pretty massive for outer system objects & accessible without the need for advanced stuff like planet cracking and solar lifting.

Re: Biggest void in space is 1B light years across (2007)

#72

Post by edgyquant »

suifbwish wrote: post #59
generalizations wrote: post #2

Posted it because it reminds me of an hypothesis I once saw, that we might be able to detect alien civilizations based on blank spots in the sky where they've managed to divert all the energy from their environment.

Why would we presume they would not think to generate a cloaked for this if they had the ability to divert all energy from their environment? Seems an obvious first order of business to avoid looking like an anomaly if you are not actively trying to be found.

How would you cloak waste heat?

Re: Biggest void in space is 1B light years across (2007)

#73

Post by ncmncm »

m4rtink wrote: post #71
ncmncm wrote: post #63

Earlier quoted context omitted.

The outer belt objects are small compared to planets, but are enormous considered as extracted volume, and uncountably numerous; whereas on inner planets you are effectively limited to the solidified skin at the bottom of an annoying gravity well, bathed in heat that must be shed. Kuiper belt distances are inconvenient only when you are in a hurry and have limited speeds. Given fusion propulsion, nothing inside a sol…

Good point - the exposed surface are for easy mining is pretty massive for outer system objects & accessible without the need for advanced stuff like planet cracking and solar lifting.

At 1G acceleration, nothing in the Kuiper belt is more than a few days away. You can send out robots if you need more mass than you have on hand.

Or, maybe you are robots, and can take 100G. Then the Oort cloud is your playground.

Re: Biggest void in space is 1B light years across (2007)

#74

Post by m4rtink »

ncmncm wrote: post #73
m4rtink wrote: post #71

Earlier quoted context omitted.

Good point - the exposed surface are for easy mining is pretty massive for outer system objects & accessible without the need for advanced stuff like planet cracking and solar lifting.

At 1G acceleration, nothing in the Kuiper belt is more than a few days away. You can send out robots if you need more mass than you have on hand. Or, maybe you are robots, and can take 100G. Then the Oort cloud is your playground.

With sustained > 1G we are effectively talking torch drives, not just "normal" fusion drives. Not many technologies we know of that might pull that off, possibly with the exception of nuclear salt water rocket.

Re: Biggest void in space is 1B light years across (2007)

#75

Post by ncmncm »

m4rtink wrote: post #74
ncmncm wrote: post #73

Earlier quoted context omitted.

At 1G acceleration, nothing in the Kuiper belt is more than a few days away. You can send out robots if you need more mass than you have on hand. Or, maybe you are robots, and can take 100G. Then the Oort cloud is your playground.

With sustained > 1G we are effectively talking torch drives, not just "normal" fusion drives. Not many technologies we know of that might pull that off, possibly with the exception of nuclear salt water rocket.

Anything we could ever cobble together is necessarily unspeakably primitive when compared to what the Oort Cloud "elder gods" perfected lo untold eons before primates first chipped rocks.

Re: Biggest void in space is 1B light years across (2007)

#76

Post by suifbwish »

edgyquant wrote: post #72
suifbwish wrote: post #59

Earlier quoted context omitted.

Why would we presume they would not think to generate a cloaked for this if they had the ability to divert all energy from their environment? Seems an obvious first order of business to avoid looking like an anomaly if you are not actively trying to be found.

How would you cloak waste heat?

What makes us so sure waste heat is something that is absolutely unavoidable. It’s possible heat maybe be disposable through some quantum means we have not uncovered yet. Ultimately everything in existence has heat potential so theoretically heat is able to covert back to everything else . Using no heat as proof the room is empty is equivalent of a person who cannot avoid making a mess when they enter a house concluding that no one else has been there because there is no mess (except the one they made) all they can conclude is that no one who makes a mess has been there.

Re: Biggest void in space is 1B light years across (2007)

#77

Post by vimacs2 »

ncmncm wrote: post #27
nynx wrote: post #11

Earlier quoted context omitted.

I've heard this idea in the context of Dyson spheres/swarms. The issue is that, while they'd be invisible or dim to the eye, the areas would be very bright in infrared.

The whole concept of Dyson Spheres, or anything even vaguely like that, is totally absurd. (Even Dyson said so.) Any space-faring culture will have mastered controlled fusion long ago, and have entirely left behind any material dependence on stars. The best places to live, then, are out in the Kuiper belts and beyond, where unlimited room and cold are available for free, and valuable gases are lying about, frozen. In…

What seems downright absurd to me is to dismiss the obvious fact that while a star might be incredibly inefficient relative to a working fusion reactor, the actual energy output of a star will far outstrip that which can be collectively produced by artificial fusion for many centuries and millennia to come.

Stars provide in abundance and for free, energy, mass (even for heavier elements they far outstrip that available on planets, asteroids, and comets), a star system spanning magnetosphere for protection from the interstellar medium, and a massive gravity well which can be used to anchor planets and mega structures alike

While it's true that we won't strictly "need" them once we have working fusion, they are likely to be the hotspots of civilisation for a long time to come, probably as long as the stellar epoch of the universe is in play (so 100+ billion years).

Re: Biggest void in space is 1B light years across (2007)

#78

Post by ncmncm »

vimacs2 wrote: post #77
ncmncm wrote: post #27

Earlier quoted context omitted.

The whole concept of Dyson Spheres, or anything even vaguely like that, is totally absurd. (Even Dyson said so.) Any space-faring culture will have mastered controlled fusion long ago, and have entirely left behind any material dependence on stars. The best places to live, then, are out in the Kuiper belts and beyond, where unlimited room and cold are available for free, and valuable gases are lying about, frozen. In…

What seems downright absurd to me is to dismiss the obvious fact that while a star might be incredibly inefficient relative to a working fusion reactor, the actual energy output of a star will far outstrip that which can be collectively produced by artificial fusion for many centuries and millennia to come. Stars provide in abundance and for free, energy, mass (even for heavier elements they far outstrip that availab…

"Hotspots" is the key term here.

For most high-civilization activities, heat is pollution, something that must be extracted and shed, in volume. Out in the Kuiper belt, cold is abundant and free.

For most high-civilization activities, a gravity well is an anchor chain. Out in the Kuiper belt, material resources, including frozen fusible gases, are abundantly accessible with very little annoying gravitation.

For many high-civiliation activities, proximity of other entities that could be put at risk, or that might put you at risk, creates hazards. Out in the Kuiper belt, room enough for anything is abundant and free.

Extreme primitives like us and bacteria, who don't have abundant private energy sources, welcome the low-intensity energy influx from a nearby star. For anybody even mildly sophisticated, the energy is uselessly diffuse. At the same time, it keeps everything at a noisily high temperature that interferes with signal integrity and fine-grained processing.

Re: Biggest void in space is 1B light years across (2007)

#79

Post by vimacs2 »

ncmncm wrote: post #78
vimacs2 wrote: post #77

Earlier quoted context omitted.

What seems downright absurd to me is to dismiss the obvious fact that while a star might be incredibly inefficient relative to a working fusion reactor, the actual energy output of a star will far outstrip that which can be collectively produced by artificial fusion for many centuries and millennia to come. Stars provide in abundance and for free, energy, mass (even for heavier elements they far outstrip that availab…

"Hotspots" is the key term here. For most high-civilization activities, heat is pollution, something that must be extracted and shed, in volume. Out in the Kuiper belt, cold is abundant and free. For most high-civilization activities, a gravity well is an anchor chain. Out in the Kuiper belt, material resources, including frozen fusible gases, are abundantly accessible with very little annoying gravitation. For many…

This is too much of an extrapolation even by the standards of envisioning things like Dyson Swarms. You are assuming that:

* It is possible to export or even host consciousness onto a digital medium - we still have no evidence for this

* All or most civilisations ultimately will want to transition entirely into a digital existence - the "entirely" part is important. If even 1% of a K-2 civilisation decided to stay organic, that would still lead to a Dyson swarm with a population approaching trillions.

* Civilisations of this tech level would do a cost benefit analysis and decide that the several orders of magnitude more resources on a star is outweighed by the inconvenience of a gravity well - I don't think orbital rings are that mass or energy intensive to build and run for this to make any sense

* There will be no future use of waste heat or method of disposal that goes beyond simple dispersal - the jury is still out on that, it may be possible to dispose of waste heat directly onto a black hole. If this turns out to be correct, the energy of a star is more than enough to power a sufficiently powerful laser array to create many in the gigatonne range.

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