61–70 of 70 posts
Earlier quoted context omitted.
There's the EM drive, maybe. Some recent discussion: https://news.ycombinator.com/item?id=12995125 If you can create trust out of electricty (ion drives also come to mind), then if you have nuclear power or fusion, things get interesting again in terms of propulsion. To reach orbit, there are a bunch of interesting proposals: skyhooks (i.e. space elevator light), launch loops, railguns.
The EM drive is reported as producing maybe 1 mN per kW. The largest power plant in the world produces about 22 GW of energy--at that ratio, an EM drive could produce maybe 22 kN. The first stage of the Saturn V rockets produced 35,000 kN of thrust. As a practical engine, EM drives are worse than chemical rockets or even ion thrusters (which produce about 25-250 mN/kW, according to Wikipedia).
My point is that there are plenty of possibilities to continue to develop propulsion technology.
Earlier quoted context omitted.
I recall the story too: if I recall correctly, it was actually a branch of chemistry we had missed, not a math problem per se. The aliens stormed off the ships with muskets and we slaughtered 'em.
Not doing any kind of reconnaissance before a conflict would be crazy! But I guess maybe they didn't think of it! It's also my working theory of why we won in Independence Day the movie :) Aliens were never warring among themselves and/or allowing any kind of a hacking culture, so didn't think to secure their systems!
They were essentially a hive mind working with a single purpose and were therefore incapable of conceiving the notion that they would need to secure their systems against an attack that essentially used their own technology against them.
Earlier quoted context omitted.
There's the EM drive, maybe. Some recent discussion: https://news.ycombinator.com/item?id=12995125 If you can create trust out of electricty (ion drives also come to mind), then if you have nuclear power or fusion, things get interesting again in terms of propulsion. To reach orbit, there are a bunch of interesting proposals: skyhooks (i.e. space elevator light), launch loops, railguns.
The EM drive is reported as producing maybe 1 mN per kW. The largest power plant in the world produces about 22 GW of energy--at that ratio, an EM drive could produce maybe 22 kN. The first stage of the Saturn V rockets produced 35,000 kN of thrust. As a practical engine, EM drives are worse than chemical rockets or even ion thrusters (which produce about 25-250 mN/kW, according to Wikipedia).
Obviously the first engine ever exhaustively tested is usually not the highest performance achievable. A factor of a thousand seems possible although a hundred is more likely.
So for a very large nuclear plant, if the EM drive were weightless (LOL) then maybe 1/10th G applied to that nuclear sub is some kind of theoretical limit not entirely ridiculous but possible.
Now consider that to one sig fig a G of acceleration for a year is the speed of light. And if you're careful maybe you could run the plant for three decades.
So a round trip to the speed of light and back again is more or less back of the envelope possible to visit some distant star.
Relativity rears its ugly head and ten years of ship time around the speed of light is a lot further than 10 lightyears and time passing on earth is a lot longer than ten years.
Of course at the speed of light you're going to need a rather substantial hull, an active radar that can avoid interstellar crud, etc. If you can detect "stuff" at a day out, at a tenth of a G accelerating for an entire day you can be quite far away indeed by the time you pass it.
I can't run the numbers in my head like above, but even 1/100th G slices a very substantial amount of time off a Mars mission. Some unverified google results imply 1/100th G means Mars in a month not a year and a half.
At least as a back of the envelope calculation its quite a useful vehicle.
Earlier quoted context omitted.
Problem is we don't really know where to go next. Jeff Bezos' Blue Origin tried to cook up alternate space travel methods for years and still couldn't come up with anything better than the same basic rocket model that put Gagarin into space. Most theorized "warp drives" either require more energy than humanity is capable of producing or necessitate breaking a law of physics or two just to move anything organic or lar…
There's the EM drive, maybe. Some recent discussion: https://news.ycombinator.com/item?id=12995125 If you can create trust out of electricty (ion drives also come to mind), then if you have nuclear power or fusion, things get interesting again in terms of propulsion. To reach orbit, there are a bunch of interesting proposals: skyhooks (i.e. space elevator light), launch loops, railguns.
Earlier quoted context omitted.
Right Ascension: 17h 11m 31.0s Declination: 11° 57' 50.9" (J2000) http://theskylive.com/voyager1-tracker It's in the constellation Ophiucus. It'll be doing a flyby of Gliese 445 in 40,000 years, but it'll be brick'd by then. http://www.space.com/22783-voyager-1-interstellar-space-star...
Geez, I wonder if anyone will find it. And since we won't even survive this century due to climate change, it'll be "a relic of a civilization long gone."
Earlier quoted context omitted.
We really are on a fragile blue ball doing loop-de-loops through space!
If you shrunk the sun down to the size of a ping-pong ball, earth would be a poppy seed orbiting ten meters away. Pluto would be 100m away. The Voyagers would be 300m away. The nearest star, Proxima Centauri, would be 500 miles away.
Correction: that should have been 10 feet (3 m). The other numbers are (more or less) correct.
Earlier quoted context omitted.
If you shrunk the sun down to the size of a ping-pong ball, earth would be a poppy seed orbiting ten meters away. Pluto would be 100m away. The Voyagers would be 300m away. The nearest star, Proxima Centauri, would be 500 miles away.
> earth would be a poppy seed orbiting ten meters away Correction: that should have been 10 feet (3 m). The other numbers are (more or less) correct.
Earlier quoted context omitted.
the proxima is almost a joke in the name.
Well, there are three stars in the alpha centauri system. Proxima is the most proximate
https://en.wikipedia.org/wiki/Alpha_Centauri#/media/File:Rel...
