Interactive Drake Equation

Chazz Michael Michaels

I found this to be a lot of fun. Share your inputs and answers.

No of stars born each year = 6
% stars with planets = 40%
Avg habitable planets per solar system = 0.2
% chance a hab planet develops life = 50%
% chance that life develops intelligence = 1%
% chance that life can communicate across space = 1%
Length of time civilisation broadcasts through space = 10,000 yrs
No times civilisation redevelops = 1

I got:

Communicating civilisations in galaxy = 0
Communicating civilisations in universe = 24bn

Capt'n Midnight

you can't just put in your own numbers - you need some science
some numbers we just don't know and they could be as near zero as makes no difference


Also you have to take into account Fermi's Paradox.

Most non-mammals on this planet reproduce from an egg, no womb needed, so ET could probably send out seed ships. It's just us mammals that need generation ships.

Also if other civilisations meet then there is likely to be technology transfer so that seeding other planets should speed up at a geometric rate.

krd

Capt'n Midnight wrote: »

Most non-mammals on this planet reproduce from an egg, no womb needed, so ET could probably send out seed ships. It's just us mammals that need generation ships.

Also if other civilisations meet then there is likely to be technology transfer so that seeding other planets should speed up at a geometric rate.

Space is vast, and the distance are huge. I just roughly calculated that if you were travelling at the speed of sound, it would take you well over a million years to get to the nearest star from our solar system.

Even if you could travel much faster - say 100th the speed of light, you'd still have a massive problems. Deep space is not a resistance-less void. The background radiation coming towards your ship would hammer it. Even if you could solve that problem, it will still take you over a 100 years to get to the nearest star.

An alien artefact just drifting in space could travel for millions of years and still get nowhere. I think, though I'm not sure, dim starlight would push it deeper into space and away from solar systems.

The first radio broadcasts on earth were made in the 1920s. Any alien civilisation at more than 90 light years away, would observe no signs of life from our planet. And they may not, even with the radio signals, as they may be just too weak to be discernible from noise.

And for the same reason, our sky may be full of planets that have advanced life and technology, but we can't see them or them us, the radio signals are just not powerful enough.

To communicate with ETs, or for them to communicate with us, we might need to build a very big transmitter. A transmitter the size of a sun - the bigger the more powerful the better. Then start broadcasting. It could take thousands of years before anyone hears it. If they're advanced as we are now, we could send them all the instructions on how to build one of our transmitters. Then even after they build their transmitters it could take thousands of years to get a reply.

Even if we had the intention of building one of these transmitters, it could take us thousands of years to get all the materials.

I think one of these gigantic beacons would be our or anyone else's only hope of communicating across space.

The beacons may already be there, we just haven't seen them yet.

I read an estimate that life could have begun on earth as early a 300 million years after it formed. There may be a physical law that governs the formation of life - and maybe it doesn't even need a Goldilocks planet like earth. It may have formed in hot rocks in deep space.

Capt'n Midnight

krd wrote: »

Space is vast, and the distance are huge. I just roughly calculated that if you were travelling at the speed of sound, it would take you well over a million years to get to the nearest star from our solar system.

Huh ?

speed of sound at normal temperature and pressure is ~ 330 meters per second. To leave the solar system you need to be going a lot faster 42,100 meters per second.

Even if you could travel much faster - say 100th the speed of light, you'd still have a massive problems. Deep space is not a resistance-less void. The background radiation coming towards your ship would hammer it. Even if you could solve that problem, it will still take you over a 100 years to get to the nearest star.

background radiation ?

An alien artefact just drifting in space could travel for millions of years and still get nowhere.

our whole galaxy is heading towards Andromoda, stars move relative to each other, some of our near neighbours will change over millions of years

The first radio broadcasts on earth were made in the 1920s. [/quote]Marconi was transmitting across the Atlantic back in 1901

To communicate with ETs, or for them to communicate with us, we might need to build a very big transmitter.

thanks to high power radar in use since the late 1940's we are probably the brightest object in our vicinity at 3GHz. The orbit around the sun and the moon and the daily rotation of the earth mean ET will get periodic variations.

you may have heard of this transmission
https://en.wikipedia.org/wiki/Arecibo_message

The message consisted of 1679 binary digits, approximately 210 bytes, transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 1000 kW.

A Mig 25 fighter's on board radar is about 500Kw



drop down to VHF and https://en.wikipedia.org/wiki/Gabala_Radar_Station

The system is a VHF system operating at a wavelength of 1.5 to 2 meters (150 to 200 MHz). Its initial transmit capacity was 50 MW with a target capacity of 350 MW

now drop down to 50Hz or 60Hz and thanks to grid synchronisation you have massive areas of the planet emitting (3 phase will null a good bit of this) of course ET would need a large antenna to pickup something with a 3,000 wavelength, wires floating in space perhaps ?

Overhead lines for trains would certainly radiate power too, and 16 2/3 Hz would be another signal we are sending

krd

Capt'n Midnight wrote: »

Huh ?

speed of sound at normal temperature and pressure is ~ 330 meters per second. To leave the solar system you need to be going a lot faster 42,100 meters per second.

I just used the speed of sound as and example of a speed. 42,100 meters per second isn't exactly the speed of light either.

background radiation ?

Yes, starlight, and the microwave background radiation. At slow speeds it's not a problem. But at high velocities it does become a problem. It's doppler shifted to higher energies.

our whole galaxy is heading towards Andromoda, stars move relative to each other, some of our near neighbours will change over millions of years

Any alien artefact will be pushed by the solar wind of any star it comes near into deeper space.

The Andromeda galaxy, is 2,500,000 light years away. Even if something was travelling at the speed of light it would take it millions of years to get there.

thanks to high power radar in use since the late 1940's we are probably the brightest object in our vicinity at 3GHz. The orbit around the sun and the moon and the daily rotation of the earth mean ET will get periodic variations.

you may have heard of this transmission
https://en.wikipedia.org/wiki/Arecibo_message A Mig 25 fighter's on board radar is about 500Kw

The Arecibo message was only at 1 MW and a real blink and you've missed it.

now drop down to 50Hz or 60Hz and thanks to grid synchronisation you have massive areas of the planet emitting (3 phase will null a good bit of this) of course ET would need a large antenna to pickup something with a 3,000 wavelength, wires floating in space perhaps ?

And we don't have an antenna like that.

Maybe the combined radio signals from all sources on earth may have the power to register at great distances, but they may not, they may just be too weak to rise about the static.

There is a chance the extraterrestrial beacons are there.

Capt'n Midnight

krd wrote: »

Yes, starlight, and the microwave background radiation. At slow speeds it's not a problem. But at high velocities it does become a problem. It's doppler shifted to higher energies.

Do the sums.

just exactly how much starlight are you expecting ?
current spacecraft can put up with a flux of 1300Kw/m2

The cosmic background radiation is 2.7K
you'd want to be going very fast to get a 100:1 to time dilation
and 100 times 2.7K is 270K

Any alien artefact will be pushed by the solar wind of any star it comes near into deeper space.

how close to a star would an object need to get for the solar wind / light pressure to significantly change the velocity of an object that is travelling ?

The Andromeda galaxy, is 2,500,000 light years away. Even if something was travelling at the speed of light it would take it millions of years to get there.

the point is that everything in our galaxy is already heading there, in fact the Magellanic Clouds will merge with our galaxy before then. There will be gravitational changes, and so stars will move. If ET has evolved in the last billion years and can reach interstellar space then they should find travel easy, you just have to wait until stars get close enough.

The Arecibo message was only at 1 MW and a real blink and you've missed it.

Yeah nearly twice the power of a Soviet era interceptor. And a tiny fraction of the military radars.

Maybe the combined radio signals from all sources on earth may have the power to register at great distances, but they may not, they may just be too weak to rise about the static..

We are 10 times brighter than the sun in radio bands. But only some bands, eg: Wifi is limited to 30mW in these parts.

krd

Capt'n Midnight wrote: »

Do the sums.

just exactly how much starlight are you expecting ?
current spacecraft can put up with a flux of 1300Kw/m2

The cosmic background radiation is 2.7K
you'd want to be going very fast to get a 100:1 to time dilation
and 100 times 2.7K is 270K

I have done the sums, and they are long. For interstellar travel you would want to go fast, or otherwise travel for aeons. The faster you go, the hotter your ship will get, until you're into the realms of high energy physics. And then you have bigger problems.

Space only seems empty when you're not going anywhere. But it is full of radiation and particles - the GZK limit slows very fast particles down but if you tried to travel at relativistic speeds those particles would gain very high energy.

But it's not to say all these problems could not be gotten around - it's just they couldn't be with anything we currently have.

how close to a star would an object need to get for the solar wind / light pressure to significantly change the velocity of an object that is travelling ?

I doesn't take much. Like there was a puzzle why voyager seemed to be veering off path - and as it turns out, it's just the way light fell on it from the sun.

Planets are too heavy to feel the effect but smaller objects would.

The interstellar winds are considered to be at equilibrium, because they're moving in every direction - they're probably not, in that there may be drifts as well as doldrums.

the point is that everything in our galaxy is already heading there, in fact the Magellanic Clouds will merge with our galaxy before then. There will be gravitational changes, and so stars will move. If ET has evolved in the last billion years and can reach interstellar space then they should find travel easy, you just have to wait until stars get close enough.

The magellan clouds are still very far away.

We are 10 times brighter than the sun in radio bands. But only some bands, eg: Wifi is limited to 30mW in these parts.

If the earth does produce that anomaly, then that's probably the thing astronomers should be looking for - planets that seem to radiating anomalously. It could be difficult or next to impossible to get coherent signals - but anomalies might show.

The trajectory for civilisation on earth may not involve humans. We may be not that far away from creating immortal robots, who wouldn't mind travelling for millions of years through space - and who could very literally teleport themselves through laser beams.



And though not absolutely relevant, I thought I might just drag this in.

http://www.bbc.co.uk/blogs/adamcurtis/2012/08/mental_channel_number_one_-_th.html

Capt'n Midnight

krd wrote: »

I have done the sums, and they are long. For interstellar travel you would want to go fast, or otherwise travel for aeons.

an aeon is a billion years

as I've already pointed you can travel intergalactic distances without leaving your own star, because galaxies will merge in that sort of time span.

Bacteria have been resuscitated after millions of years trapped in salt / amber. For even longer times the recent synthesis of a bacteria's DNA points the way for robotic probes to seed the heavens. This is way more time than is needed even with current technology. In about 40,000 years, Voyager 1 will drift within 1.6 light years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis.

Space only seems empty when you're not going anywhere. But it is full of radiation and particles - the GZK limit slows very fast particles down but if you tried to travel at relativistic speeds those particles would gain very high energy.

We aren't going to get to relativistic speeds any time soon. Daedalus might be possible. And it's good enough for us to seed the galaxy with life.

Intelligent life is a different proposition. Suspended animation is difficult for mammals. Until we develop artificial wombs we won't be heading to our terraformed planets.

The trajectory for civilisation on earth may not involve humans. We may be not that far away from creating immortal robots, who wouldn't mind travelling for millions of years through space - and who could very literally teleport themselves through laser beams.

teleporting is murder :mad:

But yeah self repairing / self replicating robots, who knows if they will be mechanical or biological or what.