Monday, October 19, 2015

Has someone passed the Great Filter ?

Scientists have for many years been speculating about the fact that the Universe shows surprisingly little sign of the actions which intelligent civilisations might attempt.

This is known as the "Fermi Paradox" and is sometimes summarised in the three words,

"Where is everybody?"

The Fermi paradox (or Fermi's paradox) is the apparent contradiction between high estimates of the probability of the existence of life on other world, such as in the Drake equation, and the lack of evidence for such civilizations. The basic points of the argument, made by physicists Enrico Fermi and Michael H. Hart, are:
  • Our Sun is a typical star, and there are billions of stars in our Milky way galaxy that are billions of years older.
  • It appears very likely that, some of these stars will have earthlike planets, and if the earth is typical, some might develop intelligent life.
  • Some intelligent life forms might develop a civilisation capable interstellar travel, a step the Earth is investigating now.
  • Even at the slow pace of currently envisioned interstellar travel, this galaxycould be completely traversed in about a million years.[6]
According to this line of thinking, the Earth should already have been visited by extraterrestrial aliens though Fermi saw no convincing evidence of this, nor any signs of alien intelligence anywhere we can observe, leading him to ask, "Where is everybody?"

Attempts to explain this rapidly become rather depressing as scientists talk about the " Great Filter which might stop life forms from reaching the point where they could begin using interstellar communications or catching light from their stars on a large scale, or any other activity we might be able to detect.

The reason such speculation can be frightening or depressing is that if whatever filters act to reduce the vast number of potential sites where civilisations might emerge to the much smaller number so far seen are not in our history and already passed, they must be ahead of us and indicate a bleak future.

Supposing for example the reason we don't see evidence of more super-civilisations in the galaxy is that the vast majority manage to wreck their planet in a nuclear war within two centuries of discovering nuclear fission, or by triggering massive global warming within three centuries of an industrial revolution, or get destroyed by Alien Space Bats or Berserker robots from space within a century of developing powerful radios which alert the aliens/robots to their presence. In any of those scenarios our chances of surviving the next couple of centuries are not good.

However:

One of the main elements of the Fermi Paradox and arguments for the Great Filter, up to now, has been that the absence of extra-terrestrial megascale engineering projects.

And now there is the faint possibility that astronomers may have found giant alien megastructures orbiting a star called KIC 8462852.

I'm told that all the scientists who have looked at this are quick to warn that although the readings from KIC 8462852 are extremely strange and very interesting, we are a long, long way from being able to confidently say what they are, and it is far too early to start jumping to the conclusion that we have found evidence of intelligent life. There is a tiny chance that these are alien megastructures but they are probably something else.

Still, even a tiny chance is encouraging. Perhaps someone 1,400 light years away, and therefore at least 1,400 years ago, may have passed the Great Filter. So we may yet pass it too ...

8 comments:

Jim said...

"Where is everyone?"

A good point on this, is really to mention the vastness of space. Its called space as, well, there is a lot of Space there. This is why its not called "stuff". :)

We humans are really bad at thinking on geological time scales, and we are bad at thinking in terms of national debts and how many tenners that actually is. We are also pretty pathetic at imagining the scales involved in space.

A good exercise everyone should do once in their lifetime, shows the scale of our own (small little solar system), its one that really, really you should try (its so much better than reading about it here so you can see it) Its called "the peppercorn method" and its really quite acurate.

Now you will need to go somewhere with a lot of room, St Bees Beach when the tide is out would be a very good place to do this. You will need a football, 4 pins, 2 peppercorns, 2 coffee beans, a hazlenut and a wallnut. (also get a good idea of how to pace out 1 yard)

so you place the football down, thats the sun.
now walk 10 yds away and place a pin (the pin head is Mercury) 10 Yds from sun
walk another 9 yds place a peppercorn (thats Venus) 19 yds from the sun
Walk another 7 yds place the second peppercorn (thats mother earth) 26yds from the sun
draw a little circle 2.5" away around the "earth" and place a pin (thats the moon)

at this point have a look and see everything ever in all of human history has taken place on that peppercorn, and the furthest we have ever been is to the pinhead 2.5 inches away.

ok now walk another 13yds and place another pin (this pinhead is Mars) 39Yds from football sun.

another 63yds place a the wallnut (jupiter) 134yds from football sun

another 113 Yds Place the hazlenut (saturn) 247Yds from football sun

another 249 Yds Place a coffeebean (Uranus) 497Yds from football sun

another 281 Yds place the other coffee bean (Neptune) 777Yds from football sun

Another 237 Yds place the last pin (pluto) 1014Yds from football sun.

now look back, you are standing over half a mile from a sun that is the size of a football (you cant see the football can you) let alone the peppercorn that is the Earth. Now you have not left our solar system yet and the question is there is it not "Where is everyone?"


now the nearest star to Earth is Promima Centauri (its 4.24 light years away) so on our scale model, I want you to go to Miami beach, look over at the pepper corn on st bees beach, with the moon in orbit 2.5 inches away, that is the scale of things. Now Where is everyone? oh we are here alright, you just are not looking hard enough.

Jim said...

Its just a really good experiment to do, do it sometime. You get used to looking at diagrams in books that can not be drawn to scale. This is a very good way of demonstrating the amount of "space" there is in Space, and how its rather easy to miss something even as massive as Jupiter, when its there all alone in space.

when we get to Interstella space then our closest neivbouring star really is over 4000 miles away when we take our 1000Yd scale. (and our earth gives the whole thing its name, thats our peppercorn)

Jim said...

also remember that during our experiment there you have the best possible chance, that is all the planets are in a line, in reality they are all in orbit around Football sun, so those pin heads, coffee beans, peppercorns etc could be anywhere along an elliptical orbit around football sun. :o)

makes a needle in a haystack seem like childs play doesn't it.

Jim said...
This comment has been removed by the author.
Jim said...

spot the deliberate mistake too (the nearest star to the Earth is of course the Sun, i had meant to say the nearest star to the sun is Proxima Centauri but oooops)

Jim said...

And in there I have laid something that deserves some thinking and private refeclection. But above all, do that experiment and see it for yourself (though I will let you off with the Miami bit)

Chris Whiteside said...

One of my teachers described a similar experiment when I was at school, with the Sun as a pumpkin and the numbers slightly greater. Perhaps it should be updated to have another pin near Pluto for Charon - and is Pluto still regarded as a planet?

Humans can manipulate very large numbers but we do not understand them as well as we do small ones: and there is a good reason we use the adjective "Astronomical" as a means of saying that a number is very large.

Jim said...

Technically no, Pluto is a Dwarf Planet

In 2005 (due to the descovery of Eris, which at that point was proposed to be named Xena, a group of scientists met to agree the definition of a planet.

1. Its large enough to be round in shape
2. It directly orbits a star (which is why Ganymede is a moon, not a planet)
3. It has cleared its orbit (this is where Pluto fails, so is now a dwarf planet)

Though I still included it, as everyone knows of Pluto, and its well loved. also it makes the mnemonic to remember them make sense - My Very Easy Method Just Simply Uses Nine Planets.

I guess in reality on the scale Pluto would be more like a grain of salt as would Charon, but then we hit the question why include the moon and Charon but not Io, Ganymede, Europa, Callisto...............

So I only really included the ones everyone (even a six year old) knows.