I gunned it, got up for coffee, and came back 200 years later having traveled over 6 million light years.
I am now in the galaxy NGC 300, very similar to the Milky Way.
Everyone I ever knew is gone.
I am sad and alone.
Relativistic Spaceship
461–470 of 500 posts
Re: Relativistic Spaceship
#462Earlier quoted context omitted.
I have a confused question here. I asked chatGPT what the approx terawatt output of the sun is. It claims it is 384.6 terawatts. I find that hard to reconcile with the earth having 12TW production. Given that your number is probably OK, that would suggest the sun output calc is way off. I wonder if any non-AI contributors have better ballpark estimates for the sun's energy output.. Hmm, I found a non-chatGPT source,…
This says we use about 1/10000 of the solar energy that hits the Earth at any given moment. https://phys.org/news/2011-10-vast-amounts-solar-energy-eart...
That's a very nice figure for context. So the energy required would be about 26% of that. That means it's more power than we could ever hope to capture from solar alone, as only about 29% of the surface is land and some of that isn't particularly great for solar (looking at you rain forests and Antarctica:)
Unless we use space-based systems instead, which would make that a kind of power requirement trivial, ignoring the costs of course ;)
Re: Relativistic Spaceship
#463I kept getting closer and closer to the speed of light, but before I crossed even 2 million light years (I think), I was staring at the Big Bang. Then I remembered that the diameter of the observable universe is about 90 billion light years (give or take), and I realized that I’m not going to be able to reach one end anywhere. There’s nothing that makes everything seem so small and insignificant like astronomy.
Re: Relativistic Spaceship
#464Earlier quoted context omitted.
A whole lot happened between the big bang and the formation of the CMB 400.000 years later.
You’re driving and see a huge patch of the fog suddenly turn red, I would argue you’re seeing break lights not fog. But that gets into definitions not just physics. Similarly, the CMB is energy from the Big Bang as last scattered ~380,000 years later. IMO, that’s the Big Bang, but reasonable people can obviously disagree.
Everything is energy from the big bang, including you and me. But the photons of the CMB don’t represent anything that already existed immediately after the big bang. Protons and neutrons and hydrogen and helium were created in between, and inflation (probably) happened in between. The universe at the time of last scattering was a whole different world than a split-second after the big bang.
Re: Relativistic Spaceship
#465Earlier quoted context omitted.
This says we use about 1/10000 of the solar energy that hits the Earth at any given moment. https://phys.org/news/2011-10-vast-amounts-solar-energy-eart...
That's a very nice figure for context. So the energy required would be about 26% of that. That means it's more power than we could ever hope to capture from solar alone, as only about 29% of the surface is land and some of that isn't particularly great for solar (looking at you rain forests and Antarctica:) Unless we use space-based systems instead, which would make that a kind of power requirement trivial, ignoring…
I'm not following the math.
Taking the US as an example: depending on who you ask, we could generate enough power for the US with somewhere between 10000 square miles (Elon math) and 21250 square miles (pretty common number given by multiple other sources) of PV.
That is about a fifth of the state of Nevada. A lot of PV, to be sure, but far from beyond hope.
And that assumes nothing but PV, which is unrealistic. We capture a bunch of the sun's energy as wind and rain.
Re: Relativistic Spaceship
#466Pff, this is cool and all, but Big Rigs trucks go much faster: https://www.youtube.com/watch?v=R8X7Vj6JXPk
Will the universe also say "You Win" when you hit the speed of light?
Re: Relativistic Spaceship
#467Earlier quoted context omitted.
I read it without any expectations and without knowing anything about the plot. It was just recommended to me by someone, but I'm usually into sci-fi, stuff like Greg Egan. I really enjoyed it, but maybe I would have been disappointed if I was expecting more of a mind melter!
Any recommendations on a mind melter?!?!? Something that is logically consistent is my only criterion (not much of a mind melter if it's incosistent within its own world) ... and the writing not being at a 10th grade level (distracting).
* spoiler alert *
yes, the writing was annoying in parts (especially the Earth flashbacks). What I liked about it was 1) if you don't know anything about it (I didn't even read the back cover) the surprises evolve nicely; and most importantly, 2) it was a story of humans cooperating with another species rather than either subjugating or resisting subjugation
Re: Relativistic Spaceship
#468Earlier quoted context omitted.
What if you define the "important" reference frame as the speed of light's (in the same direction you are going). Since c is universally constant, it seems like a reasonable privileged reference.
Doesn't really work this way. A lot of the wonkiness in SR is tied to the fact that the speed of light is the same, measured in _any_ reference frame. So, say you're on earth and you measure the speed of light... you find that it's c (~3x10^8 m/s). Now you get on a spaceship and accelerate to 0.5c with respect to earth, and you measure the speed of light relative to your spaceship... still c! In this way, you can't r…
I was thinking of this differently.
Suppose there is a starting point A from which your ship is moving away from. At the same time, a photon is shot out from A. You can take the distance traversed between A and the ship as D1, and the distance traversed by the photon as D2. Then your "percentage of C" is D1/D2.
How can you get the distance D2? I'm not sure. I guess we have to pretend it's also a ship that is traveling at C that can emit information to us (also at C :p )
Re: Relativistic Spaceship
#469Earlier quoted context omitted.
That's a very nice figure for context. So the energy required would be about 26% of that. That means it's more power than we could ever hope to capture from solar alone, as only about 29% of the surface is land and some of that isn't particularly great for solar (looking at you rain forests and Antarctica:) Unless we use space-based systems instead, which would make that a kind of power requirement trivial, ignoring…
I'm not following the math. Taking the US as an example: depending on who you ask, we could generate enough power for the US with somewhere between 10000 square miles (Elon math) and 21250 square miles (pretty common number given by multiple other sources) of PV. That is about a fifth of the state of Nevada. A lot of PV, to be sure, but far from beyond hope. And that assumes nothing but PV, which is unrealistic. We c…
Sorry for the confusion - I was referring to the energy requirements of the interstellar mission, not the power generation of the world.
Re: Relativistic Spaceship
#470Great visualization of the unintuitive nature of special relativity. It's kind of mind blowing to realize that if we could accelerate our spaceship at a mere 1G continuously, we could visit the center of the Milky Way in under 20 years (spaceship time), totally do-able in a human lifespan. Of course 27900 years would have passed on Earth, so you wouldn't be able to tell anyone about your vacation.
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.
I remember a StackOverflow question about a one-ton tungsten(?) ball heading towards Earth from the edge of the solar system, I forget how many nines after the decimal point in it's velocity. The question was what what would happen to Earth--and the very surprising answer was basically nothing. The ball would be vaporized very quickly by the interplanetary medium and disperse long before reaching Earth. Some of the energy would hit but it wouldn't be enough to notice.