>Try to get a handle on this: it takes us 2-5 years to travel two inches [in their relative scale - e.g., Voyager probes]
What? No it doesn't. We can do massively better than this, right now. As in, today's technology. No problem.
Why haven't we? It's frickin' expensive.
But the long-range probes we've launched have been pretty damn near coasting their entire trip, with a few course corrections. They were pushed, and now they float until they gain sentience and come back to say "hi". If they had a huge-ass rocket attached to them, such as would likely be on anything interested in going any distance at any kind of speed (ie, human-carrying ships), they'd get where they're going a lot faster.
Next up, to get to proxmia centauri in 42 years with some hand-waving to make things simpler and 100% efficient energy usage:
>To put this figure in perspective, the total conversion of one kilogram of mass into energy yields 9 x 1016 Joules. (Which one of my sources informs me, is about equivalent to 21.6 megatons in thermonuclear explosive yield). So we require the equivalent energy output to 400 megatons of nuclear armageddon ...
Where did 400 megatons come from, if it's equivalent to 21.6? And if 400 is "the same as the yield of the entire US Minuteman III ICBM force", I say that's a miniscule amount of energy, especially once it's divided by 20. Crank it up another 10-fold beyond 400, and we're still talking modern-day terrestrial-level achievable energy without breaking a sweat.
>So it would take our total planetary electricity production for a period of half a million seconds — roughly 5 days — to supply the necessary va-va-voom.
Not bad, really. We're pretty inefficient right now. Make it cost a few times that - we'll be producing that in a week before we can even get a lame v0.1 ship built and in trials.
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All in all, an interesting read. But it feels more like a half-accurate rant. We're waving magic wands to get 100% efficiency and 2000kg, but we're not waving magic wands to get away from conventional rockets and today's energy production levels?
I'm entirely on their side that our tech today can't get us to the stars. Totally. I agree, the energy needed is quite literally astronomical, and we're not even close to it. But we keep finding weird things with our science - I'm not writing it off entirely. And I don't see why people seem to imply that we must leave from Earth - why not mine the asteroid belt to provide the fuel at our leisure, and build a truly massive ship? We're not going to aim for the stars on our first go, we'll be living in space for a long time before then.
The 400 megatons comes from the estimate that the trip would require 2e18 joules (which is about 22x the 9e16 joules up there).
And he is getting away from conventional rockets, the 2e18 estimate assumes that the energy required to move the ship is coming from elsewhere, not carried along with the ship.
So he assumes a very small ship and mysterious ways of propelling it in order to sketch an estimate of the minimum amounts of energy involved. Ripping an even bigger hole in physics might throw acceleration and momentum out the window, but assuming 100% efficient transmission of energy across 24 light years already requires something pretty strange to us.
(his comparisons to present day production levels seem more illustrative than pessimistic)
What? No it doesn't. We can do massively better than this, right now. As in, today's technology. No problem.
Why haven't we? It's frickin' expensive.
But the long-range probes we've launched have been pretty damn near coasting their entire trip, with a few course corrections. They were pushed, and now they float until they gain sentience and come back to say "hi". If they had a huge-ass rocket attached to them, such as would likely be on anything interested in going any distance at any kind of speed (ie, human-carrying ships), they'd get where they're going a lot faster.
Next up, to get to proxmia centauri in 42 years with some hand-waving to make things simpler and 100% efficient energy usage:
>To put this figure in perspective, the total conversion of one kilogram of mass into energy yields 9 x 1016 Joules. (Which one of my sources informs me, is about equivalent to 21.6 megatons in thermonuclear explosive yield). So we require the equivalent energy output to 400 megatons of nuclear armageddon ...
Where did 400 megatons come from, if it's equivalent to 21.6? And if 400 is "the same as the yield of the entire US Minuteman III ICBM force", I say that's a miniscule amount of energy, especially once it's divided by 20. Crank it up another 10-fold beyond 400, and we're still talking modern-day terrestrial-level achievable energy without breaking a sweat.
>So it would take our total planetary electricity production for a period of half a million seconds — roughly 5 days — to supply the necessary va-va-voom.
Not bad, really. We're pretty inefficient right now. Make it cost a few times that - we'll be producing that in a week before we can even get a lame v0.1 ship built and in trials.
---
All in all, an interesting read. But it feels more like a half-accurate rant. We're waving magic wands to get 100% efficiency and 2000kg, but we're not waving magic wands to get away from conventional rockets and today's energy production levels?
I'm entirely on their side that our tech today can't get us to the stars. Totally. I agree, the energy needed is quite literally astronomical, and we're not even close to it. But we keep finding weird things with our science - I'm not writing it off entirely. And I don't see why people seem to imply that we must leave from Earth - why not mine the asteroid belt to provide the fuel at our leisure, and build a truly massive ship? We're not going to aim for the stars on our first go, we'll be living in space for a long time before then.