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The idea that nuclear weapons are what sterilized Mars is insane. Correct me if I'm wrong, but I always thought it was because Mars' core cooled, which caused

The idea that nuclear weapons are what sterilized Mars is insane. Correct me if I'm wrong, but I always thought it was because Mars' core cooled, which caused its magnetic field to go away, resulting in all its water floating off into space. No water = sterile planet. You could shoot every nuclear weapon in the world at the Earth and life would still easily carry on (maybe not multicellular, but life nonetheless), but take all the water away...

Netcob 12y ago
Let's start at the beginning. The paper talks about evidence for nuclear explosions (the word "weapon" isn't mentioned as far as I can see), and then discusses natural nuclear reactors http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor The author then argues that the evidence seems to fit an atmospheric explosion better, for example an asteroid that exploded in mid-air like in Tunguska. Or that the radioactive stuff just got there in this pattern through geological activities and other processes. Did I miss the part where he talks about nuclear weapons or sterilization?
- mhurron 12y ago
  > Did I miss the part where he talks about nuclear weapons or sterilization? Yes, it's in a different link where he 'furthers' his work. http://meetings.aps.org/Meeting/PSF14/Session/G1.3 http://meetings.aps.org/Meeting/PSF14/Session/G1.3
- huxley 12y ago
  Give this interview with Brandenburg a try: http://youtu.be/NBuN3uHnjYY http://youtu.be/NBuN3uHnjYY (courtesy of the Supreme Master Ching Hai International Association cult)
cnp 12y ago
You never really know until you know you don't know? What we know now is that we think we know -- that is, until we don't. Theories are meant to be superseded.
- roywiggins 12y ago
  Extraordinary claims, extraordinary evidence, etc. The prior probability of ancient nuclear weapons is so small that there would need to be extremely good evidence to begin to shift my appraisal of how likely it is. (am I Bayesianing right?)
  - tjradcliffe 12y ago
    Close on the Bayesianing: there's no threshold, so it isn't quite correct to say you'd need extremely good evidence to "begin to shift" your appraisal. But you'd need extremely good evidence to shift your threshold very much. Bayes' rule tells us the plausibility [$] of a proposition after taking into account some evidence should be the prior plausibility times the probability of the evidence occurring if the proposition is true divided by the probability of the evidence regardless of whether or not the evidence is true, so vastly improbable occurrences that would be way more probable if the proposition was true count as very good evidence, but lots of things can shift our degree of belief a tiny little bit. However, you are correct that the prior has such a minuscule prior plausibility that it'd take astonishing evidence that couldn't be explained otherwise to raise the posterior plausibility up to "worth taking very seriously" level. Beyond that, there is the practical consideration that we impose a threshold on our beliefs for purely pragmatic reasons. Below some plausibility it just isn't worth our time to even consider the issue. So in that sense, you are Bayesianing with the best of them. [$] I am a heterodox subjective Bayesian, in that I maintain a strict separation between "plausibility" and "probability". Plausibilities are degrees of belief by a knowing subject in a proposition, and as such are inherently subjective. Probabilities are measures of the likelihood of events, and by far the most common measure is the frequency. I take orthodox Bayesiansism to be in error by identifying plausibilities with probabilities, which is what creates the great subjective/objective quango. Bayes' rule on my view is Pl(H|E) = Pl(H)*Pr(E|H)/Pr(E) where Pr = probability and Pl = plausibility.
adventured 12y ago
There have been over 2,000 nuclear weapons detonated in the last 70 years. There are 10,000 total warheads on earth (~4,000 active). The world could fire off every one of its functioning nukes simultaneously, and it would not come even remotely close to ending multicellular life. Most of the planet would not even notice the event; it could destroy, including the damage from fallout, an area smaller than the United States. Humans of course would likely become an endangered species were the blasts spread out targeting population centers.
guard-of-terra 12y ago
It doesn't have to be directly related. Maybe aliens nuked Mars when it was green, and then much later it lost its water and most of atmosphere. Also may it be that it won't happen if an advanced civilization still looked after their home world instead of being vaporized.

Netcob 12y ago

Let's start at the beginning. The paper talks about evidence for nuclear explosions (the word "weapon" isn't mentioned as far as I can see), and then discusses natural nuclear reactors http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor The author then argues that the evidence seems to fit an atmospheric explosion better, for example an asteroid that exploded in mid-air like in Tunguska. Or that the radioactive stuff just got there in this pattern through geological activities and other processes. Did I miss the part where he talks about nuclear weapons or sterilization?

mhurron 12y ago
> Did I miss the part where he talks about nuclear weapons or sterilization? Yes, it's in a different link where he 'furthers' his work. http://meetings.aps.org/Meeting/PSF14/Session/G1.3 http://meetings.aps.org/Meeting/PSF14/Session/G1.3
huxley 12y ago
Give this interview with Brandenburg a try: http://youtu.be/NBuN3uHnjYY http://youtu.be/NBuN3uHnjYY (courtesy of the Supreme Master Ching Hai International Association cult)

cnp 12y ago

You never really know until you know you don't know? What we know now is that we think we know -- that is, until we don't. Theories are meant to be superseded.

roywiggins 12y ago
Extraordinary claims, extraordinary evidence, etc. The prior probability of ancient nuclear weapons is so small that there would need to be extremely good evidence to begin to shift my appraisal of how likely it is. (am I Bayesianing right?)
- tjradcliffe 12y ago
  Close on the Bayesianing: there's no threshold, so it isn't quite correct to say you'd need extremely good evidence to "begin to shift" your appraisal. But you'd need extremely good evidence to shift your threshold very much. Bayes' rule tells us the plausibility [$] of a proposition after taking into account some evidence should be the prior plausibility times the probability of the evidence occurring if the proposition is true divided by the probability of the evidence regardless of whether or not the evidence is true, so vastly improbable occurrences that would be way more probable if the proposition was true count as very good evidence, but lots of things can shift our degree of belief a tiny little bit. However, you are correct that the prior has such a minuscule prior plausibility that it'd take astonishing evidence that couldn't be explained otherwise to raise the posterior plausibility up to "worth taking very seriously" level. Beyond that, there is the practical consideration that we impose a threshold on our beliefs for purely pragmatic reasons. Below some plausibility it just isn't worth our time to even consider the issue. So in that sense, you are Bayesianing with the best of them. [$] I am a heterodox subjective Bayesian, in that I maintain a strict separation between "plausibility" and "probability". Plausibilities are degrees of belief by a knowing subject in a proposition, and as such are inherently subjective. Probabilities are measures of the likelihood of events, and by far the most common measure is the frequency. I take orthodox Bayesiansism to be in error by identifying plausibilities with probabilities, which is what creates the great subjective/objective quango. Bayes' rule on my view is Pl(H|E) = Pl(H)*Pr(E|H)/Pr(E) where Pr = probability and Pl = plausibility.

adventured 12y ago

There have been over 2,000 nuclear weapons detonated in the last 70 years. There are 10,000 total warheads on earth (~4,000 active). The world could fire off every one of its functioning nukes simultaneously, and it would not come even remotely close to ending multicellular life. Most of the planet would not even notice the event; it could destroy, including the damage from fallout, an area smaller than the United States. Humans of course would likely become an endangered species were the blasts spread out targeting population centers.

guard-of-terra 12y ago

It doesn't have to be directly related. Maybe aliens nuked Mars when it was green, and then much later it lost its water and most of atmosphere. Also may it be that it won't happen if an advanced civilization still looked after their home world instead of being vaporized.