Living on Mars?

[Leewei]

Mass produce probes, and have some of them be statites with collapsible solar sails. The latter group's sensory capabilities should be maximized due to the sails blocking solar radiation, and the units remaining stationary relative to obscurable stars.

It'd take a heck of a lot of probes to survey a region with an inner diameter of around 200AU (2 x pi x R, where R is 30 AU). Can you somehow quantify what you'll need and speculate on where you'll get the material to build them?

[Ravens_cry]

It'd take a heck of a lot of probes to survey a region with an inner diameter of around 200AU (2 x pi x R, where R is 30 AU). Can you somehow quantify what you'll need and speculate on where you'll get the material to build them?

Asteroids and comets? For something building current tech probes, you need water*, carbon*, metals, and silica.
*For fuel and plastics

[Leewei]

Asteroids and comets? For something building current tech probes, you need water*, carbon*, metals, and silica.
*For fuel and plastics

There's some context here. The survey is being done to find comets to use for terraforming worlds such as Venus or Mars. I'm wondering how reasonable it is to survey, since it may well be you'd use up more than you got from the Kuiper belt.

[georgie_leech]

There's some context here. The survey is being done to find comets to use for terraforming worlds such as Venus or Mars. I'm wondering how reasonable it is to survey, since it may well be you'd use up more than you got from the Kuiper belt.

Specifically Venus, as supposedly the temperature will help offset the energy input by the comet slamming into the planet, which supposedly is being done to correct the direction of rotation? Because... I can't actually follow why that's supposed to be necessary, so because reasons?

[Bohandas]

They heat the air in the oven, which transfers heat to the food through conduction. Microwave ovens use resonant frequencies to increase the effectiveness of the energy delivered to specific parts of the food based on position, which is why they tend to do things like be frozen on the outside until you bite a piece of molten cheese. Neither is really radiative heat transfer the way it works outside of the atmosphere.

based on composition

[georgie_leech]

based on composition

Partly. But the reason why relatively weak radiation is able to heat food uses both resonant frequencies, and patterns of constructive interference. It's why most microwaves rotate meals; certain areas within the microwave will be warmed faster than others, so rotating the food should ensure a more even cook. In theory at least. In practice, pockets of molten cheese continue to sit beside Frozen bits in our hot pockets

[factotum]

In practice, pockets of molten cheese continue to sit beside Frozen bits in our hot pockets

There's another reason for that behaviour--microwaves basically work by heating the water in the food, but they're not very good at heating ice. Since the heating is also uneven, as you say, and the clumps of ice are of differing sizes, you will tend to get bits that melt first and then heat very quickly while the other bits are still frozen and not absorbing microwaves very well. This is why you're supposed to stir frozen things partway through cooking, or else leave them to stand for a couple of minutes to allow the hot parts to melt the still-frozen bits.

[Rockphed]

There's another reason for that behaviour--microwaves basically work by heating the water in the food...

Microwaves also heat fats and some sugars, but mostly they heat the water.

[Bucky]

While we're on the topic of superconstruction pipe-dreams, what if we generated power by building a massive coil around a rapidly spinning magnetar (turning it into a gigantic dynamo) and running a long wire of superconducting YBCO from it back to our own solar system. Once the decades required for the electricity to travel the lightyears of distance had passed we would have a nearly unlimited supply of power.

The amount of current we can get through the wire without superconductivity breaking down is proportional to the cross-section of the wire.

Multiply that cross-section by the several thousand lightyears to the closest magnetar and you have a LOT of wire.

That means you need a lot of energy to position it. Simply dropping it off from a moving rocket isn't good enough, the wire needs to be stationary.

In fact, it's probably more energy than you could ever hope to transfer even in millions of years of operation.

Once you have the wire in place, you still need to worry about things like galactic drift, objects passing through the space occupied by the wire etc. so it's unlikely you could actually keep the wire in place for millions of years without needing to re-string it.

Oh, and the dynamo might not work as well as you want it to because superconductivity also breaks down in intense magnetic fields.

[Mando Knight]

The amount of current we can get through the wire without superconductivity breaking down is proportional to the cross-section of the wire.

Multiply that cross-section by the several thousand lightyears to the closest magnetar and you have a LOT of wire.

That means you need a lot of energy to position it. Simply dropping it off from a moving rocket isn't good enough, the wire needs to be stationary.

In fact, it's probably more energy than you could ever hope to transfer even in millions of years of operation.

Once you have the wire in place, you still need to worry about things like galactic drift, objects passing through the space occupied by the wire etc. so it's unlikely you could actually keep the wire in place for millions of years without needing to re-string it.

Oh, and the dynamo might not work as well as you want it to because superconductivity also breaks down in intense magnetic fields.

I think that at the point where you're literally building a dynamo out of a hyper-condensed star, maintaining superconductivity in the wire you're using might not actually be the most ridiculous feat you're attempting.

[factotum]

Using a super-long wire to transport power in that situation would not be practical. The relative motion of the magnetar and Sol would render it impossible. Likewise, transmitting power through some other means (say, a honkin' great laser) wouldn't work because your aim point would keep changing--you're essentially trying to hit a target moving at several hundred metres per second from information you have from several thousand years ago!

It has to be said, though, once we're at a point in our development where we could reasonably consider such a thing, we'd have to be a galaxy-spanning civilisation anyway, so send the power to somewhere much closer where we can make better use of it.