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Brown Dwarf
2010-Feb-12, 04:43 AM
I've heard many times that we have plenty of time to do this or learn to do that because the sun is going to be here for another 4 or 5 billion years. But it's my understanding that the sun's luminosity will be (and has been) slowly increasing, right up until the time that it jumps into the red giant stage.

That being said, is there a guess as to how long it will take for the sun's output to be sufficient that life here on earth will not be able to continue? When I say life, I'm mostly concerned with humankind. - This is supposing that we can dodge all of the other bullets that the solar system, galaxy, universe, ourselves, hurl at us.

01101001
2010-Feb-12, 06:13 AM
When I say life, I'm mostly concerned with humankind.

Homo sapiens? Long gone by then. Changed into one or more other species.

Evolution is lightening fast compared to the slow solar cooker. Maybe our descendants will like it warm. Who knows?

Jens
2010-Feb-12, 06:22 AM
According to this article (http://news.bbc.co.uk/2/hi/sci/tech/specials/washington_2000/649913.stm), about 500 million years before life becomes unsustainable. But in any case, as 01101001 says, humans will almost certainly be extinct by then, so not much point in worrying about it.

J Riff
2010-Feb-12, 09:32 AM
Well if 500 million years isn't long enough to evolve into something better, or build a spaceship and get out of here then we should probably give it all to the dogs and the robots, now. And the mice.

Brown Dwarf
2010-Feb-12, 02:19 PM
Ahh...500 million. I was thinking that it would be in the millions and not billions but I didn't realize it would be THAT many millions. Yes, a v-e-r-y long time...but still only 10% of the remaining life of the sun. It took us a heck-of-a long time to shrink the earth (to go from walking to flying). How long will it take to shrink the galaxy? Perhaps it can't be done, no matter how much time you have. We haven't seen evidence that anybody's been able to do it yet. (unless you watch UFO Hunters)

At least it's enough time for my Cleveland Browns to get into a super bowl...although probably not enough for them to actually WIN one. :)

Argos
2010-Feb-12, 02:23 PM
How long will it take to shrink the galaxy? Perhaps it can't be done, no matter how much time you have.

Less than a million years, if 0.25 c was achievable.

neilzero
2010-Feb-12, 08:36 PM
Near Earth's equator, close to sea level, 18 f = 10 c warmer average temperature would be fatal for humans most afternoons at 100 percent humidity, unless we could find a cool spot such as in front of an air conditioner. The ruggedized air conditioner would likely use three times as much electricity, as one designed for up to 100 f ambient air temperature, but air conditioning is likely possible at 1000 f, ambient if money is no object. Those who can afford such extravagance can likely survive, at the ambient of four billion years from now, by staying in continuous night by switching from north pole to south pole back to north pole etc. How they could earn money is hard to imagine as the oceans would be boiled dry, and most everyone and most everything long dead.
Naked humans can tolerate 150 degrees f air temperature for a few hours, daily, if the humidity is 80% or less, but probably not in full sunlight, and surfaces they touch need to be cooler. Neil

skyline5k
2010-Feb-13, 03:27 AM
At that point, I'm pretty sure money is the last thing on their minds.

Alternatively, move to Pluto?

Maddad
2010-Feb-14, 05:10 AM
29 Minute 8 Second Podcast
http://media.libsyn.com/media/astronomycast/AstroCast-080428.mp3

Transcript
http://www.astronomycast.com/astronomy/cosmology/ep-86-the-end-of-the-universe-part-1-the-end-of-the-solar-system/

April 28, 2008 Astronomy Cast did an episode on the End of the Solar System in which they covered the ideas in this thread.

One thing helpful to remember is that life first crawled out of the oceans and onto the land 500 million years ago or thereabouts. Saying that we only have 500 million left is a very long time indeed.

Chuck
2010-Feb-14, 10:50 PM
In Phoenix I get cooked every summer.

Brown Dwarf
2010-Feb-15, 02:13 AM
Thanks for the site(s) Maddad.

2/16/10 - I'm watching Hubble's Amzing Universe on the National Geographic Channel.....and some scientist was talking about the way our sun is going to die...and he has to finish up by saying that - we've got 5 billion years to get out of town. Now, I don't understand why he couldn't just say it'll become a white dwarf in 5 billion years and either leave us out of it or explain that 'due to the sun's output increasing over time, we'll have to be out of town some 4.5 billion years before that.' I mean, the show is an hour long, they've got time to give more correct information. http://www.my247forums.com/images/smilies/shrug.gif