I accelerated to 100%c, but then nothing happened. It seemed like no time passed and I didn't go anywhere. Someone help?
The universe police will be along shortly to mutate you into a large salamander. Them's the rules.
Relativistic Spaceship
121–130 of 500 posts
Re: Relativistic Spaceship
#122Earlier quoted context omitted.
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.
There is also the question of how you get the lasers to your destination in the first place.
Use lasers for the first half of the journey to send a rocket that can decelerate and build the laser station at the destination.
Re: Relativistic Spaceship
#123Earlier 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.
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 Expanse 'verse) are attached to asteroids and these are used to kinetically bombard inner planets. The results are far worse than a nuclear attack, from kinetic energy alone.
Anything capable of traveling close to the speed of light would be "death star" level planet killer. We're talking smashing through the crust and boiling off the atmosphere or if it were massive maybe even fragmenting the planet. Obviously anything even wilder like an Alcubierre Drive would be likewise. Anything capable of going to the stars within a human lifetime could annihilate worlds.
Even present-day chemical rockets could be pretty destructive. Get something massive that won't burn up (like a rod of tungsten) up to interplanetary velocities and you can approach the yield of a small tactical nuke from just kinetic energy. This has been studied at least on paper by militaries. I think the phrase "rods from God" was used by DARPA at one point for the rod of tungsten idea.
This is glossed over in the vast majority of space sci-fi. Nobody even asks in Star Trek what happens if you point the Enterprise at a planet and say "warp 9, engage!" I'm guessing it would go poorly for the Enterprise but even worse for the planet.
Re: Relativistic Spaceship
#124Earlier 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.
Sure, there are plenty of practical problems that would make the trip impossible. The fuel mass alone that would have to be shot out the back to make that trip would be something on the order of 800 million times the mass of the payload (you). So a 100kg person sitting in a 100kg spaceship would require something like 160 billion kg of fuel, assuming zero energy loss in burning the fuel. Relativistic rocket calculato…
Imagine a generation ship, consuming the energy of an entire star for the trip.
Re: Relativistic Spaceship
#125Great 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.
Could use such a ship as a time machine (well, that only goes one way).
Re: Relativistic Spaceship
#126Earlier quoted context omitted.
> Instead you have to worry about the actual speed you are traveling at 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.
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.
In short, a reference frame moving at c is pretty much a logical absurdity, because by definition it would mean having massive objects move at c as well.
Re: Relativistic Spaceship
#127I accelerated to 100%c, but then nothing happened. It seemed like no time passed and I didn't go anywhere. Someone help?
meh heh heh heh :)
Re: Relativistic Spaceship
#128Earlier quoted context omitted.
If you were to shoot it out at close to the speed of light, you'd knock the Earth out of its orbit.
an ion thruster that shoots ions out at the speed of light probably won't affect Earth
Yes because ions are... ions. You don't see photons knocking the planet out of orbit, do you? They can exert force but they don't exert that much force.
But if you're trying to avoid self-propulsion and want to launch from Earth, say, even a 200kg craft, anywhere "close to the speed of light", then that will most probably require a significant enough amount of force to knock the planet out of orbit.
Re: Relativistic Spaceship
#129Earlier quoted context omitted.
At which point shielding gets even more complicated.
Less complicated. The rocket exhaust literally forms a plasma shield in front of the decelerating rocket.
Well then, it's easy: Just always face the exhaust in that direction! It's not rocket science!
Re: Relativistic Spaceship
#130Great 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.
Could use such a ship as a time machine (well, that only goes one way).
Do you mean that someone in the space ship could, without extending their own lifespan beyond what is already expected, use the space ship to "travel" to Earth's distant future?