Tag Info

New answers tagged

3

You're absolutely correct - objects do not need to ever reach earth's escape velocity of 11.2 km/s, and many spacecraft that leave orbit, don't. That being said, note that escape velocity depends on where you are: the velocity that a cannonball 1000 km above the earth's surface would need to escape is substantially lower than that needed by a cannonball on ...


-1

Might boron carbide perhaps work? Its pretty strong, neutron absorbing, 3,000 K melting temperature, Mohs hardness is around 9.5. Density is around 2.5 g/cm^2. It is also relatively easy to produce.


1

$\theta$ is the angle made between the positive x-axis and the spacecraft's velocity vector (all at closest approach). Don't you need $\theta$ to be the angle of the spacecraft's velocity relative to Mars? Try subtracting the Mars velocity vector from the spacecraft's velocity vector, calculating $\theta$ for the resultant vector and using that angle ...


4

Assumptions we start with an observer and a star at rest with respect to each other and 1000 lightyears apart. Both observer can agree on these facts. The observer then sets out toward the star in a reasonable fast starship, arriving after 10,000 years as measured in their original frame, recording the light from the star as he goes. The traveller ...


2

Firstly, if we travel at 90% the speed of light, the relativistic effects will be too magnified to ignore. If you are travelling at a speed of $0.9c$ towards the star, according to your frame of reference, the star is coming towards you at $0.9c$ too. You'll observe that the speed of rotation of the star slows down by a factor of ...


5

We certainly would, or at least we would if we had telescopes powerful enough. However, better still, we could choose to watch its history unfold at an arbitrarily high fast-forward rate! Suppose our universe were classical/Newtonian/Galilean (or whatever you want to call it) but with a finite speed of light propagation (and let's just say that we're still ...


0

Considering that hitting a 1mg grain of dust at 0.1c speed would release the energy equivalent to an explosion of a 200 kg bomb, I really would not hold my breath. The only way I can imagine interstellar travel is as a swarm of nanobots. They would be sent on their way, and would have to be somehow decelerated at the destination. They would not carry fuel, ...



Top 50 recent answers are included