Alien life could be found within 40 years - really?

maninasia

So adding to what I worked out above; finding the earth in the milky way is similar to finding an individual glucose molecule in a disk-shaped cloud with a diameter stretching from about dundalk to dublin airport as the crow flies, and with an average thickness of about 660 metres high. And for aliens to find this in one particular century of the last 4.54 billion years, is equivalent to finding the above glucose molecule at a particular 2 milliseconds in a 24-hour day. Obviously this is all "back-of the envelope" type calculations but I find it fairly bewildering!

Nice work. The degree of complexity depends on the perspective you are viewing from. To us now finding that molecule of glucose would be quite a challenge, but it is still within the bounds of possibility especially if the glucose molecule is not moving around too much, or we know it's trajectory having developed a map of the cloud already. To an alien or an alien civilisation, this may not be much of a challenge, especially if they already have generated the galactic map.

And this is just one galaxy. I'd say there's some mad stuff going on in other galaxies. My guess is that the big bang is the result of something an advanced civilisation did, before this universe, and I think that before this universe, and probably regressing forever into the past, there was always "something", and questions about what was before that etc. just don't make sense. To me, the universe seems a bit too "young" in the grand scheme of things, seeing as it is expected to go on for trillions of years and we just *happen* to be living at the birth of it, relatively speaking... and I'm not falling for the anthropic principle here, I know humans aren't the centre of the universe, but it still strikes me as noteworthy that the big bang didn't happen that long ago.

Multiverse theory deals well with this. And to be honest it can't be helped that we view things through 'antromorphic eyes'. If the universe didn't go the way it went up to now we wouldn't be here to have this debate. But somebody else probably would. Simple as that.

We didn't arrive THAT early in my opinion. Life has been on planet Earth for about 2-3 billions years, possibly right after the crust solidified. It took an awful long time for multicellular life to get established. Then things started moving more sprightly but it took a few hundred more millions years to get around to us, an intelligent species with the potential for spacefaring. I'm sure you will agree with me though that intelligence is not neccessary for space faring..in the form of space adapted microbes.

The thing I find most surprising is..there doesn't SEEM to have been any arrival of non-Earth life on the planet since our type of life got established. If any other types of microbes did arrive they don't seem to have been able to establish themselves. I find it puzzling that we do not see any direct evidence ...but at the same time I will also consider that maybe they are here...and we just don't recognize them (or want to recognise them and fob them off as 'crazy' UFO reports)..and they don't want to show themselves right now. If aliens are aware of our existence, they are very likely to have been aware of planet Earth a long-time before we came on the scene.

Capt'n Midnight

maninasia wrote: »

The thing I find most surprising is..there doesn't SEEM to have been any arrival of non-Earth life on the planet since our type of life got established. If any other types of microbes did arrive they don't seem to have been able to establish themselves.

It's kinda hard to barge in to an established niche unless you have some advantage. And life is everywhere on this planet.

There are many types of photosynthesis here, the type that uses water as an electron donor and produces oxygen as a by-product is the most common type.

Any foreign organism probably isn't optimised for life on earth. Our oxygen atmosphere would be toxic to any life forms that existed on our planet over a billion years ago, nevermind somewhere else. The levels of Oxygen are lower than the were during the carboniferous so the giant insects of long ago wouldn't survive here because there is too little oxygen.

Things like selenium concentrations can be vital or toxic at tiny concentrations. Other elements like beryllium are rare but toxic even small changes could render large areas uninhabatable.

Yes microbes could evolve to use things like arsenic BUT only if they get a chance to do so.

Even if you ignore minerals you still have the problem of chemistry. Life here uses the same handedness of amino acids, it uses DNA and a lot of highly conserved molecules. Digestable nutrition might be hard to find for ET, many of the macro molecules might be toxic to it, many of our antibiotics are molecules that are near matches for molecules that germs use. Literally they get into and then jam up the cells machinery.

Temperature , pH , redox levels, UV levels due to composition of atmosphere - there is a chance ET evolved to break down molecules formed by lightening in an organic rich reducing atmosphere - , length of day/night etc. etc.

maninasia

Any foreign organism probably isn't optimised for life on earth. Our oxygen atmosphere would be toxic to any life forms that existed on our planet over a billion years ago, nevermind somewhere else. The levels of Oxygen are lower than the were during the carboniferous so the giant insects of long ago wouldn't survive here because there is too little oxygen.

Temperature , pH , redox levels, UV levels due to composition of atmosphere - there is a chance ET evolved to break down molecules formed by lightening in an organic rich reducing atmosphere - , length of day/night etc. etc.

Some great points above, I'm just going to be picky and point out that anaerobic bacteria and bacteria that survive on chemical energy still thrive on Earth. We might call them niches but occupying large parts of the surface of the Earth is a mighty big niche!

I agree the existing biota may make it hard to get established due to competitive pressures, along with the lack of related biota to create a supply chain of amino acids, fatty acids, glycerols, glucose and vitamins and minerals waiting to be gobbled up in ready to use form.

Environmental changes are not as intimidating as one might suspect, due to the huge diversity of environments on Earth. There are certain environments that might be more common and shared across space and solar systems, such as liquid/ice water or methane rich environments or basaltic rock.Pressures and temperatures and pHs all exist in a wide variety on a given planet or moon. There is also the abundance of amino acids and certain organic molecules across the galaxy to be considered.

You've brought up some good points and I need to do some reading on the interdependence of microbes, and how much synthesis 'de novo' they can achieve of biological molecules, at least the ones here on Earth.

ScumLord

blatherskite wrote: »

The milky way galaxy is about 6.6 billion times wider than the distance between earth and the sun, which is deemed 1 astronomical unit.

The thing is though that based on what we know about earth's position in our galaxy there seems to be a habitable zone in galaxy's.

The centre is too dense and a planet like earth couldn't form, the outer edge of the galaxy isn't habitable either, so maybe up to 50% of a galaxy just isn't likely to support life. Then they could further whittle the numbers down by ignoring stars that aren't suitable for supporting an earth like planet, or solar systems at the wrong stage of their life span.

It's still a stupendous number of planets but with our computers likely to be able to calculate those kind of numbers in practically no time within the next 50 years, their computers are probably well able to crunch that kind of data and more.

maninasia

The thing is though that based on what we know about earth's position in our galaxy there seems to be a habitable zone in galaxy's.

The centre is too dense and a planet like earth couldn't form, the outer edge of the galaxy isn't habitable either, so maybe up to 50% of a galaxy just isn't likely to support life. Then they could further whittle the numbers down by ignoring stars that aren't suitable for supporting an earth like planet, or solar systems at the wrong stage of their life span.

It's still a stupendous number of planets but with our computers likely to be able to calculate those kind of numbers in practically no time within the next 50 years, their computers are probably well able to crunch that kind of data and more.

Yep processing power and sensing power makes formerly seemingly impossible problems become solvable almost instantly.

There are a couple of quibbles I have with your post.

First you say 'life' when you should say 'life as we have found to exist on Earth'. Even then that is not clear. For instance microbes can live on an amazing number of environments and could live on comets or asteroids or space dust. There are microbes that can survive massive doses of radiation and the vacuum of space. So even your limited definition above is probably incorrect.

There is not one environment, but rather billions of microenvironments. That is the same on Earth aswell.
http://www.newscientist.com/blogs/shortsharpscience/2012/10/venus-cold-atmosphere.html


Also the habitable zone on Earth is just a very thin skin on the surface of the planet. Yet it is there. Most of the Earth is an 'unhabitable zone'.

Going back to 'life as we know it'. Well of course 'life as we know it' is not suitable for living in large areas of the galaxy. It's exactly the same as saying a fish is not suitable for living on land. But as we know there are plenty of animals and plants doing very well indeed on land...including us.

If there is an energy source and a mix of elements available it's very likely that there are millions of different types of life forms teeming in the area that you have deemed uninhabitable. I believe you deem it uninhabitable due to the radiation and supernova concerns.

Finally 99.99999% of whatever of the galaxy should be deemed uninhabitable as it is pretty much empty space. So again the term uninhabitable is not really useful terminology. This is especially true when living beings can create their own microenvironment and transportation devices just like us on Earth.