3 ms·

I can't recall the source (SciAm?), but I recall reading an article claiming that the longest impact humans can make is 16 million years. And that refers to rad

I can't recall the source (SciAm?), but I recall reading an article claiming that the longest impact humans can make is 16 million years. And that refers to radioactive isotopes. We do not have the technology to make anything that can last longer than that. (I can't even figure out how to phrase the question to google for the article.)

zimpenfish 6y ago
This might be relevant: https://www.theatlantic.com/science/archive/2019/08/arrogance-anthropocene/595795/ https://www.theatlantic.com/science/archive/2019/08/arroganc... > But the longest-lived radioisotope from radioactive fallout, iodine-129, has a half-life of less than 16 million years. If there were a nuclear holocaust in the Triassic, among warring prosauropods, we wouldn’t know about it.
- SavantIdiot 6y ago
  YES! That is it. Thank you.
camjohnson26 6y ago
Couldn’t we just make a fossil?
- SavantIdiot 6y ago
  The problem is that fossils are incredibly statistically rare. It is highly unlikely we could pick the right geological location over that time scale? How do you know where a continent is going to be in 10's of millions of years? Perhaps we could map out where plates are moving, but are we accurate enough to avoid tectonic plate subduction, erosion, volcanoes, floods, ice ages...? I think we take the statistical rarity of fossils for granted because they permeate culture: the chances of something being fossilized for hundreds of millions of years are practically nil. But not zero. Here's the article: https://www.theatlantic.com/science/archive/2019/08/arrogance-anthropocene/595795/ https://www.theatlantic.com/science/archive/2019/08/arroganc...
bombcar 6y ago
I don't see how Voyager II is not going to last longer than 16 millions years - what exists to change it?
- Turing_Machine 6y ago
  Even outside the solar system there are still some particles about, most of which are moving at high velocities. At a minimum, I would expect it to look quite thoroughly sandblasted after 16 million years.
  - bombcar 6y ago
    I suspect the size of the particles and number is very very low - effectively zero once you're far enough away from the Oort Cloud.
    - Turing_Machine 6y ago
      > I suspect the size of the particles and number is very very low The number is indeed low, though the size can be anything from a molecule to full-sized planet. On the other hand, 16 million years is a very very long time, and 17 km/s (the current velocity of Voyager 2) is a respectable velocity. Even small particles will take the "new" right off something at that velocity. By comparison, the velocity of a 5.56 mm rifle bullet is only about 1 km/s.
- SavantIdiot 6y ago
  Good question. The author didn't explore deep space. I believe it was related to terrestrial objections, but that is an interesting thought. Since nothing has ever been that far out I think it is quite impossible to say for certain, but I guess there's no reason to assume the microparticles per cubic meter are any different than inside the solar system. NASA talks about space dust here [1] and how it literally tore apart Mariner. But maybe that is just dust orbiting the sun and not something interstellar. [1] https://www.nasa.gov/vision/universe/watchtheskies/meteor_cloud.html https://www.nasa.gov/vision/universe/watchtheskies/meteor_cl...
- 6y ago

zimpenfish 6y ago

This might be relevant: https://www.theatlantic.com/science/archive/2019/08/arrogance-anthropocene/595795/ https://www.theatlantic.com/science/archive/2019/08/arroganc... > But the longest-lived radioisotope from radioactive fallout, iodine-129, has a half-life of less than 16 million years. If there were a nuclear holocaust in the Triassic, among warring prosauropods, we wouldn’t know about it.

SavantIdiot 6y ago
YES! That is it. Thank you.

camjohnson26 6y ago

Couldn’t we just make a fossil?

SavantIdiot 6y ago
The problem is that fossils are incredibly statistically rare. It is highly unlikely we could pick the right geological location over that time scale? How do you know where a continent is going to be in 10's of millions of years? Perhaps we could map out where plates are moving, but are we accurate enough to avoid tectonic plate subduction, erosion, volcanoes, floods, ice ages...? I think we take the statistical rarity of fossils for granted because they permeate culture: the chances of something being fossilized for hundreds of millions of years are practically nil. But not zero. Here's the article: https://www.theatlantic.com/science/archive/2019/08/arrogance-anthropocene/595795/ https://www.theatlantic.com/science/archive/2019/08/arroganc...

bombcar 6y ago

I don't see how Voyager II is not going to last longer than 16 millions years - what exists to change it?

Turing_Machine 6y ago
Even outside the solar system there are still some particles about, most of which are moving at high velocities. At a minimum, I would expect it to look quite thoroughly sandblasted after 16 million years.
- bombcar 6y ago
  I suspect the size of the particles and number is very very low - effectively zero once you're far enough away from the Oort Cloud.
  - Turing_Machine 6y ago
    > I suspect the size of the particles and number is very very low The number is indeed low, though the size can be anything from a molecule to full-sized planet. On the other hand, 16 million years is a very very long time, and 17 km/s (the current velocity of Voyager 2) is a respectable velocity. Even small particles will take the "new" right off something at that velocity. By comparison, the velocity of a 5.56 mm rifle bullet is only about 1 km/s.
SavantIdiot 6y ago
Good question. The author didn't explore deep space. I believe it was related to terrestrial objections, but that is an interesting thought. Since nothing has ever been that far out I think it is quite impossible to say for certain, but I guess there's no reason to assume the microparticles per cubic meter are any different than inside the solar system. NASA talks about space dust here [1] and how it literally tore apart Mariner. But maybe that is just dust orbiting the sun and not something interstellar. [1] https://www.nasa.gov/vision/universe/watchtheskies/meteor_cloud.html https://www.nasa.gov/vision/universe/watchtheskies/meteor_cl...
6y ago