4 ms·

I think you are substantially underestimating the scale of the galaxy and the vastness of space to make a claim like "dna based life probably has a monopoly on

by MiroF 6y ago

I think you are substantially underestimating the scale of the galaxy and the vastness of space to make a claim like "dna based life probably has a monopoly on water based planets throughout the galaxy"

ramraj07 6y ago
I'd argue you are also substantially underestimating the scale and numerousness of biology: your body alone has more bacterial cells than there are stars in the observable universe - all you need is one viable cell to seed an entire planet. A planet teeming with life if it was shattered due to a collision would catapult billions or trillions of seed containing rocks across the galaxy. We have three unfathomable scales competing each other - light years in distance and 100s of billions of stars, billions of years and quadrillions or more of seed cells potentially floating in space. Of course any of these factors could he off by a few orders of magnitude but it's hard to suggest one hypothesis is more valid than other without data.
- ohazi 6y ago
  Nitpick: you certainly do not actually mean the observable universe Bacterial cells in one adult human body: ~100 trillion Stars in observable universe: ~1 billion trillion You're off by seven orders of magnitude.
  - ramraj07 6y ago
    I did mean it but obviously my memory failed me and I was wrong
- krastanov 6y ago
  A quick DDG search says 10^13 bacterial cells in a human, 10^12 galaxies in the observable universe and 10^8 stars per galaxy. Your hyperbole is very off. The rest of the argument is not unreasonable, but not evidently convincing either. Certainly inspiring to think about though.
- BHSPitMonkey 6y ago
  Assuming some of the life-containing mass ejected from the collision had enough velocity to fully escape the gravity of not just the colliders but the entire star system it started in, that life would have to then survive for probably hundreds of thousands or millions of years of transit _and_ the re-entry and impact on the other life-sustaining planet it hits (assuming it hits anything, or doesn't fall into a star instead). I'm not saying it couldn't have happened, but even on a cosmic scale it sounds like it would have to be an exceedingly rare outcome.
  - pxndxx 6y ago
    Maybe it doesn't need to survive per-se, but the ejecta could have enough life building blocks (aminoacids, etc) to achieve abiogenesis easily again.
    - zaarn 6y ago
      Reentry develops sufficient heat that any complex organic molecules are torn apart by their thermal energy. And the impact is severe enough that it would likely destroy what was left.
      - dfischer 6y ago
        Tell that to the water bears: https://en.wikipedia.org/wiki/Tardigrade https://en.wikipedia.org/wiki/Tardigrade Not only is their original habitat 420 K and 1 K (absolute zero) they’re described as “colony” species. Quite interesting.
        zaarn 6y ago
        1K is not absolute zero, 0K is. 420K is 150°C, barely above boiling. In space, your temperature may range from 0.01K to over 2000K depending on solar radiation levels over the spectrum. You're exposed to higher levels of radiation and vacuum will tear at organic structures. A tradigrade can probably survive a trip to mars if they're very lucky. Better to send a huge amount of them, maybe one makes it. But interstellar distances are too vast and the time taken is too long. The DNA within tradigrades, even when hibernating, will have been torn to shreds and with no energy to repair there is no way back to life from that. I will quote form the article: > Back on Earth, over 68% of the subjects protected from solar UV radiation were reanimated within 30 minutes following rehydration, although subsequent mortality was high; many of these produced viable embryos. And that is after 10 days of exposure. If it was 400 years, it's unlikely that even 1 is able to reanimate. The hydrates species fared much worse and hydrated is more likely the state of the tardigrade when they are blown into space, rather than carefully dehydrated.
- hobby-coder-guy 6y ago
  You’re missing the point. Time.
- tekkk 6y ago
  And I think you are underestimating how hostile space is to life. Tardigrades can make it, to some extent, for a limited amount of time. Doesn't mean all life is invulnerable to near absolute zero temperature and constant radiation. Add to that the temperatures a meteor reaches when they crash through an atmosphere, granted without much an atmosphere there isn't much to generate friction. Yet the impact would still be devastating. It's certain we still don't have enough data to make any conclusions about how easy it's for life to spread. I'd wager it's less than expected yet in our galaxy, my guess would be that either hundreds or dozens of planets/moons contain life. Depends on the statistical distribution of the occurrence of life.
  - MiroF 6y ago
    > Tardigrades can make it, to some extent, for a limited amount of time. Yeah but likely not for tens of thousands of years in the void between space + cosmic radiation?
m463 6y ago
4 billion years life has been on earth.
rimliu 6y ago
Also overestimating the possible speed of travel.
grimgrin 6y ago
*life that needs water probably has a monopoly on water

by MiroF 6y ago

ramraj07 6y ago

I'd argue you are also substantially underestimating the scale and numerousness of biology: your body alone has more bacterial cells than there are stars in the observable universe - all you need is one viable cell to seed an entire planet. A planet teeming with life if it was shattered due to a collision would catapult billions or trillions of seed containing rocks across the galaxy. We have three unfathomable scales competing each other - light years in distance and 100s of billions of stars, billions of years and quadrillions or more of seed cells potentially floating in space. Of course any of these factors could he off by a few orders of magnitude but it's hard to suggest one hypothesis is more valid than other without data.

ohazi 6y ago
Nitpick: you certainly do not actually mean the observable universe Bacterial cells in one adult human body: ~100 trillion Stars in observable universe: ~1 billion trillion You're off by seven orders of magnitude.
- ramraj07 6y ago
  I did mean it but obviously my memory failed me and I was wrong
krastanov 6y ago
A quick DDG search says 10^13 bacterial cells in a human, 10^12 galaxies in the observable universe and 10^8 stars per galaxy. Your hyperbole is very off. The rest of the argument is not unreasonable, but not evidently convincing either. Certainly inspiring to think about though.
BHSPitMonkey 6y ago
Assuming some of the life-containing mass ejected from the collision had enough velocity to fully escape the gravity of not just the colliders but the entire star system it started in, that life would have to then survive for probably hundreds of thousands or millions of years of transit _and_ the re-entry and impact on the other life-sustaining planet it hits (assuming it hits anything, or doesn't fall into a star instead). I'm not saying it couldn't have happened, but even on a cosmic scale it sounds like it would have to be an exceedingly rare outcome.
- pxndxx 6y ago
  Maybe it doesn't need to survive per-se, but the ejecta could have enough life building blocks (aminoacids, etc) to achieve abiogenesis easily again.
  - zaarn 6y ago
    Reentry develops sufficient heat that any complex organic molecules are torn apart by their thermal energy. And the impact is severe enough that it would likely destroy what was left.
    - dfischer 6y ago
      Tell that to the water bears: https://en.wikipedia.org/wiki/Tardigrade https://en.wikipedia.org/wiki/Tardigrade Not only is their original habitat 420 K and 1 K (absolute zero) they’re described as “colony” species. Quite interesting.
      - zaarn 6y ago
        1K is not absolute zero, 0K is. 420K is 150°C, barely above boiling. In space, your temperature may range from 0.01K to over 2000K depending on solar radiation levels over the spectrum. You're exposed to higher levels of radiation and vacuum will tear at organic structures. A tradigrade can probably survive a trip to mars if they're very lucky. Better to send a huge amount of them, maybe one makes it. But interstellar distances are too vast and the time taken is too long. The DNA within tradigrades, even when hibernating, will have been torn to shreds and with no energy to repair there is no way back to life from that. I will quote form the article: > Back on Earth, over 68% of the subjects protected from solar UV radiation were reanimated within 30 minutes following rehydration, although subsequent mortality was high; many of these produced viable embryos. And that is after 10 days of exposure. If it was 400 years, it's unlikely that even 1 is able to reanimate. The hydrates species fared much worse and hydrated is more likely the state of the tardigrade when they are blown into space, rather than carefully dehydrated.
hobby-coder-guy 6y ago
You’re missing the point. Time.
tekkk 6y ago
And I think you are underestimating how hostile space is to life. Tardigrades can make it, to some extent, for a limited amount of time. Doesn't mean all life is invulnerable to near absolute zero temperature and constant radiation. Add to that the temperatures a meteor reaches when they crash through an atmosphere, granted without much an atmosphere there isn't much to generate friction. Yet the impact would still be devastating. It's certain we still don't have enough data to make any conclusions about how easy it's for life to spread. I'd wager it's less than expected yet in our galaxy, my guess would be that either hundreds or dozens of planets/moons contain life. Depends on the statistical distribution of the occurrence of life.
- MiroF 6y ago
  > Tardigrades can make it, to some extent, for a limited amount of time. Yeah but likely not for tens of thousands of years in the void between space + cosmic radiation?

m463 6y ago

4 billion years life has been on earth.

rimliu 6y ago

Also overestimating the possible speed of travel.

grimgrin 6y ago

*life that needs water probably has a monopoly on water