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Relativistic Spaceship

dmytry.github.io

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Re: Relativistic Spaceship

#361

Post by mihaaly »

noduerme wrote: post #350

So, this does seem to take the angle I'm flying at into account. If I'm accelerating to 99.9% the speed of light, and I yaw 180deg the view, I start "decelerating". What happens if I keep maximum acceleration and pitch up 90deg? The software seems to keep flying on the original vector. Is this a bug or is it intended to be a simulation of how light would behave under those circumstances?

Not the way I see it. If I accelerate modestly (0.2m/s2) to just above 30% of c where the movement is noticable enough and then put the direction of travel just beyond one of the corners (e.g. just beyond the top right) by turning the view then the direction of travel will move slowly towards the center of the screen on its own - giving a slight sense of turning in the beginning - as one would expect of current velocity vector and the velocity accummulated from acceleration vector (always towards the center) add up. At velocities close to c the already huge velocity vector dominates and no chance of perpendicular (or any angled) acceleration make any effect on the velocity vector direction: the diagonal of the two can never go beyond c. The velocity vector locks in. (probably why those traveling near the speed of light don't age much, their particles cannot interact that freely with each other when their movement is locked in to a common travel vector?).

And here I'd observe that the acceleration value is measured in the local system where time slows down relative to the observer's system, while the speed is measured in the observer's system (naturaly, my speed relative to me is always zero).

Re: Relativistic Spaceship

#362

Post by ozim »

insane_dreamer wrote: post #303
The_Colonel wrote: post #297

Earlier quoted context omitted.

I think Hail Mary (and Astronaut) is more suited for people who don't usually like sci-fi.

I like sci-fi, and enjoyed Hail Mary very much

It is not a bad book but I'd say for sure over-hyped. As much as I enjoyed reading it, I would not recommend it as "must have" if someone was into "The Martian". It is not a "must have" more like it is OK for general public and for hardcore sci-fi fans I would say that I can see how it could be disappointing. But yeah no one can easily appease hardcore fans anyway :)

Re: Relativistic Spaceship

#363

Post by thro1 »

ahazred8ta wrote: post #149
api wrote: post #123

Earlier quoted context omitted.

> it’s conjectured that the colonists already at your destination won’t appreciate you boiling the atmosphere when you hit them with blue shifted radiation. There's a general principle known as Jon's Law (not sure where the name comes from) that any powerful space drive is by definition a weapon of mass destruction. You see this in The Expanse when incredibly powerful fusion torchship rockets (a major part of the Exp…

Larry Niven's Known Space gave us the Kzinti lesson: "a reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive." -- https://tvtropes.org/pmwiki/pmwiki.php/Main/WeaponizedExhaus...

https://tvtropes.org/pmwiki/pmwiki.php/Literature/KnownSpace

(Be warned: it's a deep hole)

Casual Interstellar Travel:

Most hyperdrives just need to be Neptune’s distance from a star to work - two light hours; the Q-II needs to be five - Pluto’s! This means it can get you from any given human world in Known Space to any other in no more than eleven hours, but also no less than ten hours for any world outside the system.

There’s no intermediate setting. With most hyperdrives, a pilot can leave the helm unattended most of the time. If one does so in a Q-II for more than two minutes, they’re almost certain to crash into a star. It doesn't have an on-off switch, either, it has a grip that has to be kept or the drive turns off.

Re: Relativistic Spaceship

#364

Post by holoduke »

EA-3167 wrote: post #168
slow_typist wrote: post #66

Earlier quoted context omitted.

But accelerating by 1 g is very convenient for the crew. No muscle and bone degeneration, no space sickness, etc.

It would be cheaper in every sense to turn something like a giant asteroid into a rotating habitat ship than achieve a constant 1g to even the closest systems. Realistically interstellar travel is not a thing that (biologically modern) humans will ever be suited for, robotic probes don't need thousands of kg of food and water to stay alive, don't need artificial gravity, air, or entertainment. The fact that the trip…

Rotation wont really work unless the structure is gigantic (many miles in diameter) otherwise you will suffer from dizziness. Rotating spaceships like in many movies are probably making everyone on board sick.

Re: Relativistic Spaceship

#365

Post by mihaaly »

klyrs wrote: post #18

Yikes. At around 90%c, it's starting to look like a sunny day. Any physicists care to weigh in on the accuracy of this? I can search for the energy density of starlight in interstellar space... but how fast does one need to go to hit that "sunny day" point?

I wonder how long one would enjoy the view of that sunny day when all the visible light, infrared and high radio frequencies coming our way are turned into high energy x-ray and gamma frequencies due to the doppler effect.

Re: Relativistic Spaceship

#366

Post by denton-scratch »

eru wrote: post #300
StevePerkins wrote: post #258

Earlier quoted context omitted.

Indeed. We can't even agree on whether or not there's an extra Neptune-sized gas giant out beyond the orbit of Pluto, and that's right here in our OWN solar system!

So? Even ten extra Jupiters or thousand extra suns would take up only a tiny amount of space compared to the size of the solar system out to Pluto: The distance from the sun to Pluto is about 5.9 billion km. The radius of the sun is about 696,340 km. The ratio of radii is about 8,473. Cube that to get the ratio of volumes, and you get 608,263,848,559 for the ratio of volume in a sphere out to Pluto vs volume of the s…

> The radius of the sun is about 696,340 km

Arguably, the entire heliosphere is part of the Sun's atmosphere, and it reaches well beyond Pluto. If I were in a relativistic spaceship, I think I'd want to apply the brakes well before slamming into the heliosphere.

What do you call the heliosphere of a star that isn't the Sun? The stellosphere?

Re: Relativistic Spaceship

#367

Post by denton-scratch »

api wrote: post #123
perardi wrote: post #28

Earlier quoted context omitted.

Unless you could somehow make an Alcubierre warp drive. Of course…even if that was possible, it’s conjectured that the colonists already at your destination won’t appreciate you boiling the atmosphere when you hit them with blue shifted radiation. https://www.universetoday.com/93882/warp-drives-may-come-wit...

> it’s conjectured that the colonists already at your destination won’t appreciate you boiling the atmosphere when you hit them with blue shifted radiation. There's a general principle known as Jon's Law (not sure where the name comes from) that any powerful space drive is by definition a weapon of mass destruction. You see this in The Expanse when incredibly powerful fusion torchship rockets (a major part of the Exp…

> This has been studied at least on paper by militaries.

I thought these weapons were real and deployed. Specifically, I understand that hypersonic missiles don't really need an explosive warhead; a hypersonic tungsten rod would make a bigger explosion than any conventional warhead.

Re: Relativistic Spaceship

#368

Post by kreeben »

soco wrote: post #357
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…

There we go again, Americans using anything but the metric system :) scnr

>> baseball

How large is one of those, even? I much prefer to work with perfectly spherical Olympic swimming pools.

Re: Relativistic Spaceship

#369

Post by bocytron »

> Now you are staring into the big bang in all its glory; make sure to wear safety squints.

Wait what? That's not true right? All the light we see is concentrated in one point but it's not really the big bang that we see, it's an illusion, is that correct?

Re: Relativistic Spaceship

#370

Post by xattt »

GuB-42 wrote: post #193
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…

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.

X-ray sources would turn to gamma rays. Not that it’s any better that X-rays. Other comments suggested lead plates. It would quickly get irradiated and would probably need to get shed as soon as you got to a destination.
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