71–80 of 500 posts
Earlier quoted context omitted.
Acceleration vs speed. Adjust the acceleration until the "The ship is flying at X% the speed of light" is almost zero.
I did... after approaching near 100% speed of light, I decelerated, but it refuses to budge below around 45%. I accelerated both axes.
Earlier quoted context omitted.
> As an SF writer, it's pretty interesting, though, to think of the weird shapes a society would take when your astronauts are outliving entire civilizations. I guess this all depends on how you define simultaneity. Say I got on a relativistic rocket traveling near c and colonized Planet X in 10 years ship time and say 20,000 years Earth time. I put up my TV antenna as soon as I land, and I'd still be receiving Earth…
While traveling near c, I believe you'd be receiving Earth transmissions from approximately the same time you left, Earth clocks would appear to slow down to a crawl. But if you land on another planet and change reference frame to be more "stationary" again relative to Earth, I think a massive amount of Earth time would suddenly appear to have elapsed very quickly during the process of slowing/landing because of the…
Earlier quoted context omitted.
Of course it’s not microwaves anymore, but it’s still the CMB, that is, decoupling/recombination, not the big bang. Unless you count the CMB as the big bang.
Its remnant, its echo, or just the big bang, however you want to see it.
Earlier quoted context omitted.
One gee over the course of months is insane . Even if you converted the entire "fuel" reaction mass directly into momentum, you're still carrying tens or hundreds of thousands of tons of fuel for any remotely habitable spacecraft. And no engine has perfect mass conversion. Matter-Antimatter has been simulated to be maybe sixty percent efficient, fusion is around 17%, nuclear pulse propulsion a surprising 7%, fission…
In the book series The Expanse, that was pretty much the only unrealistic technology that the humans had, which allowed them to colonize the solar system. Sure, there was some might-as-well-be-magic alien stuff later in the book, but by page 1, humans have colonized the solar system, purely with a hand-wavy engine that can generate sustained thrust without needing tons of reaction mass and without turning your exhaus…
Earlier quoted context omitted.
One gee over the course of months is insane . Even if you converted the entire "fuel" reaction mass directly into momentum, you're still carrying tens or hundreds of thousands of tons of fuel for any remotely habitable spacecraft. And no engine has perfect mass conversion. Matter-Antimatter has been simulated to be maybe sixty percent efficient, fusion is around 17%, nuclear pulse propulsion a surprising 7%, fission…
Can you explain why matter-antimatter only has 60% efficiency?
I love that someone wrote and published a serious paper where the end design involved first stage thrust of 550 million ft-lbs and the total ship weighs something like 17 million metric tons and if I'm reading page 26 correctly, the payload on the ship has to be 7,500 kilometers from the ignition source to survive.
https://www.relativitycalculator.com/images/relativistic_pho...
Earlier quoted context omitted.
What if you didn't carry the fuel? Use stationary lasers from your starting point to power your journey half way until you lasers from your destination to slow your craft down.
The farther you get, the dimmer the laser gets. The faster you get, the less energy each photon has.
It's fun to think that this is the closest we could ever come to time travel. I hope someday somebody actually gets to experience this.
Earlier quoted context omitted.
I wonder what is a safe acceleration to get to light speed for long periods without hurtin too much
You can’t “get to” light speed, that’s one of the big punchlines in relativity. If you pick an acceleration equal to the acceleration we experience on Earth (aka 1g, aka ~9.8m/s^2), you hit relativistic speeds (speeds at which you need to take into account the effects of relativity to do anything) surprisingly fast. On the order of hundreds of days. So, it is not really a matter of safe acceleration on a long space t…
That's the other big punchline in relativity: There's no one "actual speed" because that implies that there is a single "important" frame of reference wherein those atoms are floating around waiting to be hit by a spaceship.
Earlier quoted context omitted.
What if you didn't carry the fuel? Use stationary lasers from your starting point to power your journey half way until you lasers from your destination to slow your craft down.
Of all the dangers associated with spaceflight it's a pretty interesting concept to add "lasers at the origin shut off for whatever reason" and "lasers at the destination never turn on / are misaligned / turn on too soon / turn on too late" to the list. Not sure I'd want to be in a spacecraft careening through the cosmos with no realistic way to slow it down.
This is something I've wanted to try in VR one day. Does anyone know if there is an app/game available for one of the popular headsets? Is there a technical limit to how realistic the effect could be?
Even though we can perceive the "depth" of the stars through motion in this simulation, every star is still going to look equally far away, because their positions won't change between the left and right eyes. The same way we can't perceive the sun as further away than the moon -- depth perception merely tells us they're both "max far away".
You could always introduce depth perception by faking your eyes to be light-years apart, but of course that's not how it would really be in the spaceship...