Aliens in 1500 years

[arkie87]

I stumbled upon this article from Cornell, claiming that we can expect to encounter alien life within 1500 years. The basic idea is that once our signals reach half the volume of the Milky Way, it's reasonable to assume that an alien civliation will detect them.

In the words of the author(s): 

" Combining the equations for the Fermi Paradox and the mediocrity principle, the authors suggests Earth might hear from an alien civilization when approximately half of the Milky Way Galaxy has been signaled in about 1,500 years. "

Now i'm no expert, but the diameter of the milky way is 100,000 ly. How is it possible that within 1500 years, radio signals will reach half the volume? Am i crazy?

Link to Article

Edited June 16, 2016 by arkie87

[G'th]

Yeah I think a figure is missing here, as the article itself is referencing a rate of 1 light year a year for all of our signals, meaning that by 1500 years from now, our "bubble" will only be 1580 ly wide.

What it might be talking about is the expected amount of stars/planets reached by our signals at that time should equate to about half of whats present in our galaxy, but a rough crunch of the numbers still indicates a far cry from "half".

 

 

[arkie87]

1 minute ago, G'th said:

Yeah I think a figure is missing here, as the article itself is referencing a rate of 1 light year a year for all of our signals, meaning that by 1500 years from now, our "bubble" will only be 1580 ly wide.

What it might be talking about is the expected amount of stars/planets reached by our signals at that time should equate to about half of whats present in our galaxy, but a rough crunch of the numbers still indicates a far cry from "half".

 

 

Thanks for the reply.

I found the actual (non peer-reviewed) article: here

I think what's needed is the fact that the author computes that there are 210 civilizations out there also broadcasting for the same amount of time. If you compute (1500/ 32000)^2*210 you get approximately 0.5.

[Shpaget]

They are obviously talking nonsense.

Quote

As Earth’s electronic ambassador, TV and radio signals are sent into space as a byproduct of broadcasting. These signals have been traveling from Earth for 80 years at the speed of light.

They speak of the broadcasts as if they were the primary means of communications with the aliens. Our TV and radio broadcasts are not emitting into space - that would make no sense. They are emitting towards the ground - that's where all the receivers are. The minuscule amount that seeps up can not reach 80 ly, let alone, 1500 ly and still be usable.

 

[arkie87]

11 minutes ago, Shpaget said:

They are obviously talking nonsense.

They speak of the broadcasts as if they were the primary means of communications with the aliens. Our TV and radio broadcasts are not emitting into space - that would make no sense. They are emitting towards the ground - that's where all the receivers are. The minuscule amount that seeps up can not reach 80 ly, let alone, 1500 ly and still be usable.

 

What about Kerbal broadcast towers?

[Shpaget]

What?

[Dfthu]

Radio and TV signals will degrade over time. The waves will start to spread out and become unreadable.

10 minutes ago, arkie87 said:

What about Kerbal broadcast towers?

Assuming they send out focused signals towards other planets. More powerful and they are more focused then radio signals, they could last hundred's of lighting years depending on the power of the signal.

EDIT: wait, if Kerbal broadcast towers are like radio towers on earth it would be the same way, degrading over time. If you mean the KSC tracking station then it could send out messages.

Edited June 16, 2016 by Dfthu

[HebaruSan]

18 minutes ago, arkie87 said:

I think what's needed is the fact that the author computes that there are 210 civilizations out there also broadcasting for the same amount of time. If you compute (1500/ 32000)^2*210 you get approximately 0.5.

That makes more sense. But then what are they supposing will happen at that point? Any first contact event between any two of those civilizations? Sounds like the author was wrong to insert Earth into that sentence.

[arkie87]

1 minute ago, HebaruSan said:

That makes more sense. But then what are they supposing will happen at that point? Any first contact event between any two of those civilizations? Sounds like the author was wrong to insert Earth into that sentence.

Now we can debate if 210 makes sense. It seems like 210 is the expected number of civilizations to have evolved over the lifetime of our galaxy. Even if that number is correct, assuming they all still exist and are all just starting to broadcast signals is ridiculous IMO

10 minutes ago, Dfthu said:

Radio and TV signals will degrade over time. The waves will start to spread out and become unreadable.

Assuming they send out focused signals towards other planets. More powerful and they are more focused then radio signals, they could last hundred's of lighting years depending on the power of the signal.

EDIT: wait, if Kerbal broadcast towers are like radio towers on earth it would be the same way, degrading over time. If you mean the KSC tracking station then it could send out messages.

I was mostly making a joke. Everyone knows Kerbal broadcast towers are such high power. That's why Kerbals are green.

And when they accidentally aim them at your ship, you get kracken attacks. 

[Streetwind]

1 hour ago, G'th said:

Yeah I think a figure is missing here, as the article itself is referencing a rate of 1 light year a year for all of our signals, meaning that by 1500 years from now, our "bubble" will only be 1580 ly wide.

What it might be talking about is the expected amount of stars/planets reached by our signals at that time should equate to about half of whats present in our galaxy, but a rough crunch of the numbers still indicates a far cry from "half".

It might be worth remembering that the galaxy is not static; star systems orbit it at wildly differing speeds and distances, just like planets orbit stars. That means that the area covered by our radio waves is larger than a first approximation with a static model suggests. Additionally, new stars will regularly pop into that area while old ones exit.

It's still a weird statement about "half the galaxy", though - I agree on that front.

[arkie87]

2 minutes ago, Streetwind said:

It might be worth remembering that the galaxy is not static; star systems orbit it at wildly differing speeds and distances, just like planets orbit stars. That means that the area covered by our radio waves is larger than a first approximation with a static model suggests. Additionally, new stars will regularly pop into that area while old ones exit.

Are you sure that the relative velocities matter compared to the speed of light?

[G'th]

13 minutes ago, Streetwind said:

It might be worth remembering that the galaxy is not static; star systems orbit it at wildly differing speeds and distances, just like planets orbit stars. That means that the area covered by our radio waves is larger than a first approximation with a static model suggests. Additionally, new stars will regularly pop into that area while old ones exit.

It's still a weird statement about "half the galaxy", though - I agree on that front.

That is a good point, but still, the numbers are far too astronomical (heh) for that to make up the massive difference between the math and what the article is claiming.

[Streetwind]

11 minutes ago, arkie87 said:

Are you sure that the relative velocities matter compared to the speed of light?

They don't have to matter compared to the speed of light, but rather compared to the time scale we're talking about. I mean, it's not like we're rounding the galaxy or anything, but 1600 years isn't a short period of time.

 

1 minute ago, G'th said:

That is a good point, but still, the numbers are far too astronomical (heh) for that to make up the massive difference between the math and what the article is claiming.

Yeah, who knows what the author really meant with that statement...

[Shpaget]

20 minutes ago, Streetwind said:

They don't have to matter compared to the speed of light, but rather compared to the time scale we're talking about. I mean, it's not like we're rounding the galaxy or anything, but 1600 years isn't a short period of time.

It's still five orders of magnitude short of one rotation of Sun around the galaxy.

[PB666]

This thread and the fermi paradox thread should have been merged.

http://gizmodo.com/new-calculation-shows-we-ll-make-contact-with-aliens-in-1782029426?

This is the second time in two days I have been putting forth a hypothesis and then something pops out to confirm it.

The condition here is that its all based on unconfirmed statistics.

 

[Scotius]

Maybe, instead of looking for modulated signals (that degrade with time and distance covered) we should simply look for stars that produce more electromagnetic "white noise" than they should? Sure, it's not foolproof, but if we find a Sun-like star that generates twice the amount of radio static that G class star should, it could mean something's afoot

[magnemoe]

13 hours ago, Shpaget said:

They are obviously talking nonsense.

They speak of the broadcasts as if they were the primary means of communications with the aliens. Our TV and radio broadcasts are not emitting into space - that would make no sense. They are emitting towards the ground - that's where all the receivers are. The minuscule amount that seeps up can not reach 80 ly, let alone, 1500 ly and still be usable.

 

Yes, first they assume 210 civilizations guessing parameters in the drake equations. then they assume the relevant one is listening and is capable of picking up broadcasts from earth in 1500 years, adding lots on guesswork on top of the first. 
 

[Findthepin1]

Given the estimate of 210 civilizations having existed since the Milky Way formed, and the Milky Way's age of 13.21 billion years, one can expect a civilization to form once every 62 904 761 years (plus 330 days and 11 hours and 28 minutes and 36.48 seconds, lol). So, about once every 63 million years. So the last civilization before us probably existed just a short time after the extinction of our dinosaurs, and is almost definitely not still here today.

[Shpaget]

Well, life likely needs a metal rich environment. Our Sun is a third generation star, rich in heavy elements and is only 4,5 b years old. Other life bearing planets should need about the same time to form.

Perhaps stellar life cycles are shorter near the galactic core, but it still takes a few billion years for a hydrogen cloud to produce heavy elements.

[GarrisonChisholm]

17 hours ago, Dfthu said:

Radio and TV signals will degrade over time. The waves will start to spread out and become unreadable.

Assuming they send out focused signals towards other planets. More powerful and they are more focused then radio signals, they could last hundred's of lighting years depending on the power of the signal.

EDIT: wait, if Kerbal broadcast towers are like radio towers on earth it would be the same way, degrading over time. If you mean the KSC tracking station then it could send out messages.

Whenever I read @Dfthu 's comments, no matter how sanguine and sophisticated they may be, I hear them in Arnold's voice...

Edited June 16, 2016 by GarrisonChisholm

[arkie87]

12 minutes ago, GarrisonChisholm said:

Whenever I read @Dfthu 's comments, no matter how sanguine and sophisticated they may be, I hear them in Arnold's voice...

Raydeo Sihgnahls weel deegrayde Ovah Tyme!

[GarrisonChisholm]

24 minutes ago, arkie87 said:

Raydeo Sihgnahls weel deegrayde Ovah Tyme!

...I think that would be "tHyme" actually, he lingers to reveal invisible & silent consonants.  :]

[arkie87]

3 minutes ago, GarrisonChisholm said:

...I think that would be "tHyme" actually, he lingers to reveal invisible & silent consonants.  :]

Preepahre tu bea terhminayted!

[PB666]

18 hours ago, Shpaget said:

They are obviously talking nonsense.

They speak of the broadcasts as if they were the primary means of communications with the aliens. Our TV and radio broadcasts are not emitting into space - that would make no sense. They are emitting towards the ground - that's where all the receivers are. The minuscule amount that seeps up can not reach 80 ly, let alone, 1500 ly and still be usable.

That's a problem, but my prediction is that it will take 600+ years with perfect technology, it could take 15000 years without any active efforts on our part to reach out to aliens, we would be waiting for them to broadcaste signals. 

[Snark]

13 hours ago, PB666 said:

The condition here is that its all based on unconfirmed statistics.

If by "unconfirmed statistics" you mean "totally made-up numbers," then yes.

I always find this kind of speculation to be, well, silly.  "Don't know" means "don't know."

It's true that there are a lot of things we can estimate reasonably well:  How many stars are there?  What fraction of them are the right combination of size and longevity to give them a stable habitable zone?  Of those, how many of them likely have planets with the right conditions?

However, no matter how you slice the numbers, there are several giant, whopping, totally unknowable numbers that make everything else moot:

• Given a planet that has the right conditions for life on it... how likely is it that life will actually occur?
• Given that life occurs... how likely is it that it will develop intelligence?
• Given that it develops intelligence... how likely is it that it will develop technology?
• Given that it develops technology... how long does its civilization last?

We have absolutely zero basis for estimating any of those.  Certainly a lot of ink has been spilled speculating about it, but it all comes down to glorified arm-waving.

The biggest one is the first one.  We simply don't know how likely life is.  It could be that a planet with the right conditions is overwhelmingly likely to develop life if you give it a few billion years, and it happens pretty much every time.  Or it could be so spectacularly unlikely that it's only happened once in this galaxy, and of course we're it because, well, we'd kind of have to be, wouldn't we?  We just don't know.  And there's really no way to know the answer, or even make a guess within many, many orders of magnitude.  You can't draw a line through one data point.

This is why the search for evidence of life on Mars (present or past) is of such overwhelming interest.  If we can find any example of life not on Earth, then that completely changes everything-- if it happened more than once just in our solar system, that would indicate that it's so common that it must be all over the place.  (The converse is not true; even if we could somehow definitively establish that no life has ever existed in our solar system beyond Earth, that wouldn't really prove anything.)