PDA

View Full Version : Why Finding Alien Life Would Be Bad. The Great Filter



Fraser
2018-Feb-01, 04:50 PM
Kurzgesagt just released a new video all about the Great Filter. It's great, and it's unsettling.
The post Why Finding Alien Life Would Be Bad. The Great Filter (https://www.universetoday.com/138447/finding-alien-life-bad-great-filter/) appeared first on Universe Today (https://www.universetoday.com).


More... (https://www.universetoday.com/138447/finding-alien-life-bad-great-filter/)

The Backroad Astronomer
2018-Feb-01, 05:32 PM
Maybe there many small roadblocks on the way to galactic civilizations rather then a filter.

ronin
2018-Feb-03, 01:20 PM
IMO opinion life is very common throughout the Universe but advanced life is likely rare and sentient species even more so and very likely those are brief lived due to self destruction and environmental degradation.

Humans (and life as we know it) only exist thanks to a multitude of unlikely events.

1) The Thea impact that gave Earth it's moon, larger molten core and thus a stronger magnetic field.
2) Mitochondria development shown in the video.
3) The mutation that allowed the switch from anaerobic to aerobic metabolism as waste oxygen levels rose to poisonous levels in the early atmosphere.
4) The reset of the evolutionary tree caused by the Permian–Triassic extinction, life would have been much different without the loss of 96% of it's diversity.
5) The Cretaceous–Tertiary extinction that wiped out the dinosaurs and allowed mammals to dominate the land.

That's just a few.

Ross 54
2018-Feb-03, 04:57 PM
Hmm... The speculation that a 'great filter' even exists is based on our not detecting any advanced extraterrestrial civilizations, so far. If these civilizations exists, but we've simply failed to detect them, then there is no need for a great filter. A number of reasons, other than a great filter, for the non-detection of ET civilizations have been explored in the scientific literature.

Earth could reside within a preserve of sorts, set aside to allow it to develop on its own. This would foster a greater diversity of life in the galaxy, something that humans have already begun to value on our own planet.

Dr. Jill Tarter, of the SETI Institute, has attempted to explain the non-detection of extraterrestrial civilizations. She likens our detection efforts, so far, to scooping up a cupful of sea water, finding no fish therein, and concluding that no fish exist in the ocean, as a whole.

Jens
2018-Feb-04, 02:15 AM
Dr. Jill Tarter, of the SETI Institute, has attempted to explain the non-detection of extraterrestrial civilizations. She likens our detection efforts, so far, to scooping up a cupful of sea water, finding no fish therein, and concluding that no fish exist in the ocean, as a whole.

I find that pretty reasonable. Space is really big, so itís quite possible that we simply havenít looked enough.

Jeff Root
2018-Feb-04, 02:48 PM
I also agree with Ross 54's final paragraph. We have just
begun to look.

The key is having an idea of what we should expect to have seen
with the looking we've done so far. I have a hard time coming up
with anything that we should have seen so far. I have not thought
of anything that seems likely. All the possibilities seem unlikely.

There are a host of speculative explanations of the Fermi paradox.
But there is an explanation that is *not* speculative, and which has
the enormously significant feature that -- unlike most speculative
explanations -- it is sufficient. By itself, it explains why we have not
yet detected ETI: Interstellar travel and interstellar broadcasts are
extremely expensive. So expensive that they are rarely attempted.
Part of the expense is time. Both are so expensive, so likely to fail,
and take so long when they succeed that they rarely succeed in the
rare situations that they are attempted.

There could very well be other reasons we don't see ETs that are
more immediate, more severe than the expense, but those reasons
are speculative. The expense is known, and sufficient to explain
what we (don't) see.

People everywhere will be interested in exploring the rest of the
Universe. Some will be motivated enough to overcome the expense,
endure the time, and risk the dangers. But they can't do it in such
a way as to make it commercially self-supporting. Travel between
stars is a one-way trip. Communication between stars takes so
long that it is essentially a one-way trip, not a conversation, not an
exchange. So it has no commercial value. It certainly has great
scientific, artistic, cultural, and emotional value. It even has the
potential to preserve an entire culture that is threatened by a local
disaster. But it is too expensive, too slow, and too risky to be the
basis for interstellar commerce. So it will only be done rarely, not
regularly and frequently.

-- Jeff, in Minneapolis

Ross 54
2018-Feb-04, 04:02 PM
Interstellar travel, and even communications would be very slow and costly for a civilization at about our level of technical development. This might not continue to be the case for a much more advanced civilization. It is not clear that some means of circumventing the light speed limit defined by relativity theory will never be possible.

Jeff Root
2018-Feb-04, 06:03 PM
I take as more-or-less a given that nothing can travel faster than
light, and nothing very large can reach speeds close to the speed
of light, because there is no indication that it is possible. Not even
the slightest suggestion of a hint. What looked for a while like
possible FTL neutrinos turned out to be just a bad connection in
timing equipment. So the only basis we have for the idea of FTL
is wishful thinking. I'm not averse to wishful thinking, but it helps
to have something more than that to build on.

Technology may advance, but the ways in which it can advance
and the degree to which it can advanced are limited. If there are
no limits to anything, then no rules can describe anything, and all
science is worthless. Which is contrary to my experience.

-- Jeff, in Minneapolis

DaveC426913
2018-Feb-04, 08:58 PM
Yeah, the article makes the very big assumption that, if an alien species is out there, we will see signs of it.
Or rather it makes the corollary assumption: since we do not currently see any, the only plausible reason is that they are not there.

The article is happy to make lots of guesses about other civilizations and their fates, but not once does it doubt that first, big assumption.

I see Ross has already, rather more eloquently, addressed these points.

DaveC426913
2018-Feb-04, 09:06 PM
I know lots of people have put numbers to the Drake equation and made stabs at the number of civilizations in our galaxy.
Has anyone taken that one step further and imagined what our sky should look like?


i.e.
- there are (were) A planets with some form of life within B light years of us.
- there are (were) C planets with some starfaring life within D light years of us.
- E number of those planets should still be broadcasting
And therefore, our sky should have the following signatures, with a distribution of F.

Jens
2018-Feb-05, 02:11 AM
Interstellar travel, and even communications would be very slow and costly for a civilization at about our level of technical development. This might not continue to be the case for a much more advanced civilization. It is not clear that some means of circumventing the light speed limit defined by relativity theory will never be possible.

No, it is not clear, but to me there is a fairly convincing bit of evidence, namely what we observe. I can imagine two scenarios: either (a) FTL is physically impossible, or (b) it is possible but we haven't found the mechanism/loophole. If (b) is true, then you sort of wonder why we don't see lots of alien life. You have to make up scenarios like the "cosmic preserve" or some kind of filter to explain things. However, is (a) is true, then what we actually see basically makes sense. As Jeff points out, in a world without FTL travel, interstellar travel is really tough, and not something that would often be attempted. So the fact that we appear to be alone in the universe, even though it is nearly certain we are not alone in the universe, makes sense.