by Sixstrings » Tue 10 Aug 2010, 16:24:14
$this->bbcode_second_pass_quote('EnergyUnlimited', 'W')hat about slow oxygen depletion to 16%?
I think current oxygen levels are about 25%. So what happens at 16%? How much time before it gets down to that level?
My guess would be that a 16% ratio wouldn't mean extinction.. there are native people living in the Andes who've actually evolved larger lungs to deal with the lower oxygen levels. This is why some of these South American countries do so well in the World Cup -- their lungs are better and they don't get out of breath as much.
Even at doom levels of low oxygen, I would assume there would be higher content in certain regions (low altitude). Weather is complex, so you could see bands of habitable land develop.
When talking about extinction, to make it through a bottleneck all we need is one viable group. With not much more than stone age tech, homo sapiens can live in any climate on the planet -- form the hottest desert to the coldest tundra. Pretty much everywhere except Antarctica.
Humans are living everywhere on the planet. So when judging the viability of a species, that's a good thing -- we're not limited to a particular region or climate.
$this->bbcode_second_pass_quote('', 'W')hat about genetic degeneration due to advanced medicine?
That will be a VERY long term process. If we actually evolve dependence on medication, then that means business as usual will have continued for so long that we've nothing to worry about anyway.
But also don't forget that most people on the planet are NOT popping pills everyday -- the vast majority are dirt poor and don't live in the lap of luxury. Unlimited access to medications is a first world phenomenon, not the norm.
$this->bbcode_second_pass_quote('', 'W')hat about degradation of Y chromosome? etc.
Sounds interesting, don't know anything about it, could you elaborate?
$this->bbcode_second_pass_quote('', 'T')here are also certainly many species far more survivable than we are.
Nearly all microorganisms are coming to mind but there are also tiny, microscopic spider like animals which can survive vacuum of space for years..
by SeaGypsy » Tue 10 Aug 2010, 20:48:42
$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('SeaGypsy', '
')Estimates are that the closest possible habitations are 270 light years away, giving a round trip electronic signal a 540 year travel time. Rediculous in the extreme. Also through the journey no communication will be possible as the signals from earth would not be able to catch up with the light speed craft.
Any estimates, how far it might be to nearest habitable planet are pie-on-the-sky wizardry.
We simply don't know.
On the other hand you don't understand relativity theory, even the most basic premises of it.
Spacecraft flying at speed of light would get to arbitrary location
in no time at all, so there would be no multigenerational flight even if destination is in Andromeda Galaxy.
However there is a snag:
Marginally below speed of light relativistic mass of your craft would be sufficient to cause its gravitational collapse into BH.
NB.
As per my opinion Hawking's ideas about leaving Earth are sci-fi Utopia.
We will go extinct regardless , did we move out or not btw.
2nd Law of Thermodynamics is an ultimate warranty of that.
I don't understand relativity? Light has a defined speed, which may be somewhat variable. It does not travel at infinite speed and time is a requirement for a journey at any speed. Can you explain where you get "no time at all" from? If you are talking quantum mechanics that has nothing to do with engineered spacecraft, more in common with mystic yoga.
Ultimately the sun will go super nova and fry this planet, this is a given. Also ultimately the entire universe will decay to the point of near enough to zero energy, leaving no habitability anywhere. In the 1st instance we are talking about hundreds of millions or billions of years, in the second of maybe much longer.
I have no idea where sixstrings 40 or 50 thousand years comes from.
The figure of 270 light years is pretty much arbitrary but is not a figure plucked out of thin air, it is based on observations of other solar systems nearby and trying to guess conditions on the planets in them. It is possible that arriving there would prove that another journey is mandatory.
Personally I find this thinking to be egotistical wankery in the extreme and a very sad indication of humanities hopelessness and readyness to abandon the reality we have for a fantasy we will never have.
by frood » Mon 16 Aug 2010, 16:30:19
$this->bbcode_second_pass_quote('SeaGypsy', '')$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('SeaGypsy', '
')Estimates are that the closest possible habitations are 270 light years away, giving a round trip electronic signal a 540 year travel time. Rediculous in the extreme. Also through the journey no communication will be possible as the signals from earth would not be able to catch up with the light speed craft.
Any estimates, how far it might be to nearest habitable planet are pie-on-the-sky wizardry.
We simply don't know.
On the other hand you don't understand relativity theory, even the most basic premises of it.
Spacecraft flying at speed of light would get to arbitrary location
in no time at all, so there would be no multigenerational flight even if destination is in Andromeda Galaxy.
However there is a snag:
Marginally below speed of light relativistic mass of your craft would be sufficient to cause its gravitational collapse into BH.
NB.
As per my opinion Hawking's ideas about leaving Earth are sci-fi Utopia.
We will go extinct regardless , did we move out or not btw.
2nd Law of Thermodynamics is an ultimate warranty of that.
I don't understand relativity? Light has a defined speed, which may be somewhat variable. It does not travel at infinite speed and time is a requirement for a journey at any speed. Can you explain where you get "no time at all" from? If you are talking quantum mechanics that has nothing to do with engineered spacecraft, more in common with mystic yoga.
Ultimately the sun will go super nova and fry this planet, this is a given. Also ultimately the entire universe will decay to the point of near enough to zero energy, leaving no habitability anywhere. In the 1st instance we are talking about hundreds of millions or billions of years, in the second of maybe much longer.
I have no idea where sixstrings 40 or 50 thousand years comes from.
The figure of 270 light years is pretty much arbitrary but is not a figure plucked out of thin air, it is based on observations of other solar systems nearby and trying to guess conditions on the planets in them. It is possible that arriving there would prove that another journey is mandatory.
Personally I find this thinking to be egotistical wankery in the extreme and a very sad indication of humanities hopelessness and readyness to abandon the reality we have for a fantasy we will never have.
I would give Hawking some slack on this as he didnt say anything about getting to the next habitable planet. Its the biodome wonderland on the Moon for us most likely.
One thing about Hawking is he isnt saying what he really wants to say and thats not extinction by asteroid because asteroids are so 90s and contain toxic levels of Ben Affleck, he is just bumping up the need to get a serious budget to the space programme thats being cut to ribbons using his status. I would if I was him as it really needs it.
by EnergyUnlimited » Wed 18 Aug 2010, 03:49:38
$this->bbcode_second_pass_quote('SeaGypsy', '')$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('SeaGypsy', '
')Estimates are that the closest possible habitations are 270 light years away, giving a round trip electronic signal a 540 year travel time. Rediculous in the extreme. Also through the journey no communication will be possible as the signals from earth would not be able to catch up with the light speed craft.
Any estimates, how far it might be to nearest habitable planet are pie-on-the-sky wizardry.
We simply don't know.
On the other hand you don't understand relativity theory, even the most basic premises of it.
Spacecraft flying at speed of light would get to arbitrary location
in no time at all, so there would be no multigenerational flight even if destination is in Andromeda Galaxy.
However there is a snag:
Marginally below speed of light relativistic mass of your craft would be sufficient to cause its gravitational collapse into BH.
NB.
As per my opinion Hawking's ideas about leaving Earth are sci-fi Utopia.
We will go extinct regardless , did we move out or not btw.
2nd Law of Thermodynamics is an ultimate warranty of that.
I don't understand relativity? Light has a defined speed, which may be somewhat variable. It does not travel at infinite speed and time is a requirement for a journey at any speed. Can you explain where you get "no time at all" from? If you are talking quantum mechanics that has nothing to do with engineered spacecraft, more in common with mystic yoga.
Time for moving object counts different than for a stationary "reference" one.
t' = t*1/sqrt(1-v2/c2) where t' is time perception by= moving object compared to time perception by observer of this object.
The effect of such situation is that as speed of object grow, time percepted by it seems shorter.
So for v=0.9c we have:
t' = t*1/sqrt0.19 = 2.29t
So for every 2.29 seconds counted by observer, moving object counted only 1 second.
So if we have sent a craft to Alpha Centaurii (4.2 light years away) with speed 0.9 c, we would observe that it arrived there after 4.66 years (nothing strange here) but astronauts on said craft would record only 4.66/2.29 =
2 years long flight and this is what makes relativistic effects interesting.
for v = c we get:
t' = t* 1/sqrt0 = "infinity"*t
So our astronaut traveling at v = c would not precept time at all and would find itself
instantaneously in arbitrary location of Universe.
$this->bbcode_second_pass_quote('', 'U')ltimately the sun will go super nova and fry this planet, this is a given.
by EnergyUnlimited » Wed 18 Aug 2010, 04:10:22
$this->bbcode_second_pass_quote('Sixstrings', '
')$this->bbcode_second_pass_quote('', 'W')hat about degradation of Y chromosome? etc.
Sounds interesting, don't know anything about it, could you elaborate?
http://legacy.signonsandiego.com/news/s ... 1c12y.html $this->bbcode_second_pass_quote('', '&')quot;Given the rate of decay since it began," Steve Jones writes, "the Y might disappear altogether within a mere 10 million years."
And what then?
$this->bbcode_second_pass_quote('', '')$this->bbcode_second_pass_quote('', '[')i]"Performance of the past is not necessarily a guideline to performance of the future". Ever heard that?