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Relativistic Spaceship

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Re: Relativistic Spaceship

#311

Post by hakuseki »

BoiledCabbage wrote: post #239
sophacles wrote: post #115

Earlier quoted context omitted.

That's not how it works. If the planet is N light years away from earth, the transmissions you receive would be those sent 20000-n years ago. along the way you'd get most of the messages sent during the 20k years as very red-shifted light, and extremely rapidly from your pov.

I think you may have that wrong (If I'm understanding you correctly). If you traveled at the speed of light then you'd be at the planet in 0 time your time, and you would arrive with the first of the broadcasts over those 20k years. So once on the planet you'd get to watch all 20k years of broadcasts. If you traveled at 1/2 the speed of light (not focusing on your dilation for the moment), then you'd still beat 50% o…

Are you planning to decelerate by crashing into the planet at relativistic speed?

Re: Relativistic Spaceship

#312

Post by PerryCox »

goblinux wrote: post #188
CobrastanJorji wrote: post #169

Earlier quoted context omitted.

You could imagine a technically advanced society using it as a sort of penal death sentence. "You were not safe around our people, so we are sending you to the end of time."

Isn’t that the plot of Skyrim?

In Skyrim they didn't send Alduin into the end of time, just into the future (also there is going to be an Elder Scrolls VI so V can't be the end of time, but will likely be the end of the fifth era). It was one of the reasons that the Felldir the Old was not onboard with the plan to use the Elder Scroll on Alduin. They didn't know how far into the future he would be sent. Most people on Nirn at the time of Skyrim didn't believe that dragons were real, much less Alduin who signals the end times. The Dragonborn ultimately ends up defeating Alduin, but because Alduin is immortal (in a way that the other dragons are not) he will return at a time deemed by his father Akatosh and actually destroy all of existence in that universe.

Going back to your original point it's a little different than sending him to the end of the universe, they sent him forward in time, but they actually had no idea how far or where there were sending him.

Re: Relativistic Spaceship

#313

Post by heads »

MilStdJunkie wrote: post #26
AlexAndScripts wrote: post #15

Earlier quoted context omitted.

I suppose you would also have to worry about surviving the trip - every atom in the interstellar medium would damage your ship, likely penetrating the entire way through, and electromagnetic repulsion would only work with charged particles.

Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cubic meter. Your ship might look like a very, very long shooting star. Probably dialing the speed down a touch would be worth it for whatever your shielding material is, but who knows? We're talking miracle engines here. I think in the "Valkyrie" ship-on-a-stri…

If you’re doing 2e8 m/s, your ship is long and thin with a 1m3 nose cone, and space has 100 baseballs per m3 then you’re being hit by 2e10 baseballs a second. How do I get an idea for what 20 billion baseballs (2TJ) feels like?

Apparently bullets are about an order of magnitude more energetic than baseballs (800J vs 80J) so I guess I could try to build my intuition based on being shot ~2 billion times a second instead. A kiloton of TNT is 4GJ, so it’s also like a 500 kiloton bomb going off every second.

Dropping 5e5kg of rock into the worlds biggest dumpster truck at 10m/s yields 25MJ of chaos so it’s also like a parking lot of 80,000 of those being filled with a continuous stream of rubble. That’s probably the best analogy given that we’re talking about machinery — your spaceship needs to have the build resilience of tens of thousands of dumpster trucks but condensed into the cross sectional area of a dinner table.

Re: Relativistic Spaceship

#314

Post by mr_mitm »

antihipocrat wrote: post #197
GuB-42 wrote: post #193

Earlier quoted context omitted.

Even if you managed to avoid matter, at some point, photons will start to become a problem. As you continue to accelerate, eventually, the cosmic microwave background itself will become deadly X-rays.

Would a layer of water in the forward hull positions mitigate this?

To a point, sure. Lead would be better. Some joke that this is the reason why Klingons have these thick foreheads.

Re: Relativistic Spaceship

#315

Post by kaashif »

heads wrote: post #313
MilStdJunkie wrote: post #26

Earlier quoted context omitted.

Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cubic meter. Your ship might look like a very, very long shooting star. Probably dialing the speed down a touch would be worth it for whatever your shielding material is, but who knows? We're talking miracle engines here. I think in the "Valkyrie" ship-on-a-stri…

If you’re doing 2e8 m/s, your ship is long and thin with a 1m3 nose cone, and space has 100 baseballs per m3 then you’re being hit by 2e10 baseballs a second. How do I get an idea for what 20 billion baseballs (2TJ) feels like? Apparently bullets are about an order of magnitude more energetic than baseballs (800J vs 80J) so I guess I could try to build my intuition based on being shot ~2 billion times a second instea…

> A kiloton of TNT is 4GJ, so it’s also like a 500 kiloton bomb going off every second.

Funnily, my first reaction to this comparison is that it makes it seem more plausible to me that this is possible. After all, a Star Destroyer can take gigaton level hits!

But the problem with that is Star Destroyers are fictional.

I've been spending too much time on spacebattles.com.

Re: Relativistic Spaceship

#317

Post by wordpad25 »

micw wrote: post #307
wongarsu wrote: post #180

Earlier quoted context omitted.

100 atoms per cubic meter is on the lower end of typical densities in the interstellar medium. It can get many orders of magnitude denser than that. Outside galaxies you have better chances of surviving high speeds. The intergalactic medium is only 1-10 particles per cubic meter in the web of gas we call the warm–hot intergalactic medium, and possibly less outside of that.

So would probably better to get out of the galaxy disc, travel -fast- to the other end and dive back into rather that go straight through the galaxy?

Except we can't get to edge of the galaxy quickly.

I guess Hitchhikers guide to the galaxy building space highways destroying everything in the way could be more than a gag after all.

Re: Relativistic Spaceship

#318

Post by heads »

kaashif wrote: post #315
heads wrote: post #313

Earlier quoted context omitted.

If you’re doing 2e8 m/s, your ship is long and thin with a 1m3 nose cone, and space has 100 baseballs per m3 then you’re being hit by 2e10 baseballs a second. How do I get an idea for what 20 billion baseballs (2TJ) feels like? Apparently bullets are about an order of magnitude more energetic than baseballs (800J vs 80J) so I guess I could try to build my intuition based on being shot ~2 billion times a second instea…

> A kiloton of TNT is 4GJ, so it’s also like a 500 kiloton bomb going off every second. Funnily, my first reaction to this comparison is that it makes it seem more plausible to me that this is possible. After all, a Star Destroyer can take gigaton level hits! But the problem with that is Star Destroyers are fictional. I've been spending too much time on spacebattles.com.

The numbers are big but they don’t seem “big big” like Sagittarius A* is big or the distance to Andromeda is big.

Re: Relativistic Spaceship

#319

Post by heads »

jemfinch wrote: post #305
wincy wrote: post #291

Earlier quoted context omitted.

Another good one for me is that a cubic light year or butter would immediately collapse into a black hole with a Schwarzchild radius larger than the observable universe.

It's impossible for your fact and the fact you're replying to both be true. Water is denser than butter, and the nearest star to the sun is about 4.3ly away; if your fact were true, the universe would be a black hole. A cubic lightyear is about 8.468e+50 liters, and butter weighs 911 g/L, giving the mass of a cubic lightyear of butter to be 7.714348e+50, whose Schwarzchild radius is about 121,103,293 lightyears, abou…

Wasn’t one of the great puzzles of the 20th century exactly this — will the universe collapse back into a singularity or not?

Re: Relativistic Spaceship

#320

Post by j4yav »

TaylorAlexander wrote: post #269
MilStdJunkie wrote: post #26

Earlier quoted context omitted.

Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cubic meter. Your ship might look like a very, very long shooting star. Probably dialing the speed down a touch would be worth it for whatever your shielding material is, but who knows? We're talking miracle engines here. I think in the "Valkyrie" ship-on-a-stri…

What do you mean “the energy of a baseball”? A baseball at what speed?

A baseball at football speed, of course
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