Stephen Hawking, LM, Stephen Hawking

[rcjordan]

I'm not the only grim one, LM.

Stephen Hawking says humans must colonize another planet in 100 years or face extinction

https://finance.yahoo.com/news/stephen-hawking-says-humans-must-065221051.html

[littleman]

It is interesting that he went from humanity having 1,000 years down to a century to get our sh## together.  I agree with him that we are already in a time when there is real danger of our capability outstripping our ability to reason.  There are so many potential pitfalls.

I guess what gets to me is how much some are just willing (almost hoping) to set their own home on fire.

Case in point:
https://www.vice.com/en_us/article/nothing-wrong-with-rolling-coal-711

I guess I would ask Hawking what makes him think humans could sustainable colonize Mars* when we can't maintain life on Earth.  Mars, at best, would just end up a lifeboat for the rich and lucky.  Honestly, I think the biggest danger we face is the special breed of nihilism mixed with consumerism we have brewing today.

^{*or space station, asteroid, whatever}

[buckworks]

>> colonize Mars* when we can't maintain life on Earth

That is the question ...

[rcjordan]

Counterpoint:

What Stephen Hawking Gets Wrong In His Viral Prediction That Humans Should Escape Into Space In 100 Years

http://www.techtimes.com/articles/206947/20170509/what-stephen-hawking-gets-wrong-in-his-viral-prediction-that-humans-should-escape-into-space-in-100-years.htm

[Rooftop]

Guillen does not mince words in stating his views on Hawking, whom he describes as the "Donald Trump of science, given to saying outrageous things for the fun of it and to attract attention." - See more at: http://www.techtimes.com/articles/206947/20170509/what-stephen-hawking-gets-wrong-in-his-viral-prediction-that-humans-should-escape-into-space-in-100-years.htm#sthash.04npje6I.dpuf

Cue Trump claiming to be the "Professor Hawking of politics"

[littleman]

I don't completely agree with Guillen.  I absolutely think it is important to have a vibrant space program -- it fuels discovery and is inspiring.  Also, as Tyson loves to say, the dinosaurs didn't have a space program.   However, I think the argument that we need to be off planet because we may destroy this one is silly.   Lets say WW3 starts and we also have millions on Mars at the time; do you think the people on that planet would be able to ride the war out?  I am pretty sure any technology that could bring people to the red planet would be able to lob some nukes too.

[Mackin USA]

"Also, as Tyson loves to say, the dinosaurs didn't have a space program."

I agree

The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea's interior. However, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another major mass extinction, the Triassic-Jurassic extinction event, that wiped out many groups and allowed dinosaurs to assume dominance in the Jurassic.

[rcjordan]

http://www.telegraph.co.uk/science/2017/06/20/human-race-doomed-do-not-colonise-moon-mars-says-stephen-hawking/

[littleman]

He must be spewing the hyperbole because he thinks it will get public support behind the space programs.  We are probably centuries away from humans traveling interstellarly.  I don't think people understand how far the stars are away from each other.

Alpha Centauri distance = 4.367 light years = 25.67 trillion miles

I hope I live long enough to see up close images of Alpha Centauri's planets come back from Yuri Milner's project.  What I'd really be thrilled about though is evidence of simple life living somewhere else in our own solar system.  I think discovery of life out there is a better motivation (at least for me) than some vague notion of space saving us from ourselves because we are too short sighted to conserve what we have.

[rcjordan]

Hawking and Musk seem to think alike on this issue. They're also both showboats.

[ergophobe]

We are probably centuries away from humans traveling interstellarly.  I don't think people understand how far the stars are away from each other.

Alpha Centauri distance = 4.367 light years = 25.67 trillion miles

1000 tons to half light speed: 1.8 x10^7 terawatts assuming 100% efficient matter/antimatter anhiliation engine that expells fuel at .1c
https://www.quora.com/How-much-energy-needed-to-push-a-space-craft-to-half-speed-of-light

A Nimitz class carrier is 97,000 tons. It can pull things like water from the sea and bring in some fresh food resupply from tender ships or aircraft. This space ship is going to need to travel for at least a decade, probably more assuming a max speed of .5c. On the other hand, the a carrier is not optimized for low weight. Still, I'm going to assume that if you have to bring everything, including systems to refresh oxygen and water and all the food you'll ever need, plus the supplies you'll depend on to set up your colony, you'll need at least 5 aircraft carriers, plus probably a pre-arrival fleet and a post-arrival pipeline. But we'll just assume 5x the tonnage of a Nimitz carrier

That means its going to need 9 * 10^12 terawatts of power to accelerate to .5c

Now, since it is going to have to actually decelerate at the other end, it's going to need some huge number greater than that (at least 1000 times more, since every kg of deceleration fuel requires 732kg of acceleration fuel to get it to .5c, but I expect the math is way more complicated... I think it's going to be exponential not linear).

I don't even know where to start there, but conservatively, we're talking 9*10^18 terawatts.

Anyway, total solar energy landing on earth is 84 Terawatts per day. Let's call it 90 to make it easy.

That means you would have to harvest every photon of solar energy hitting the earth for 10^18 days to get enough energy to fuel this ship

So that's roughly 3*10^14 years of harvesting all the solar energy that lands on the earth. Now, of course, we're destroying things in an antimatter/matter drive, but still, it's a lot of energy. Way more than all the fossil fuel and wood and solar and wind power that have ever existed in the history of the planet, all fueling one ship.

And if want to go somewhere further away than Alpha Centauri, you're going to need to get to more than .5c or you're going to need something bigger than a carrier fleet.

[littleman]

Right, which is why ET hasn't visited here yet.

That said, I am fascinated by Project Orion:
https://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29
(I think I've mentioned it here before?)

It is basically the idea of using nukes to power a space craft, in theory we'd be able to get to 10-12% the speed of light.

[littleman]

An alternative nucular propultion method (a bit more elegant):
https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

Instead of boom___boom___boom, this would be continuous thrust like a conventional rocket,

2,700 tonnes of highly enriched uranium salts in water to propel a 300 tonne spacecraft up to 3.6% of the speed of light

[littleman]

This is a pretty good dive into project Orion.  At the end of the video they do a dive into some more recent proposals that are based on Orion that would be a bit safer and easier to engineer.