Which constant should we send to aliens?

[danne89]

Suppose we get contact with some aliens, which number constant should you send to test their "intelligence"?

 

[Ryoukomaru]

I would send $$\phi=1.61803399$$ - The Golden Ratio

 

[master_coda]

I would send $$\phi=1.61803399$$ - The Golden Ratio

How exactly would we send that number? Without an encoding they could understand, it wouldn't matter what number we sent.

 

[DeadWolfe]

Well, ignoring that problem, I would say (pi^2)/6

 

[Alkatran]

e^(pi*i) + 1 = 0

 

[WORLD-HEN]

You could send them a golden rectangle.

 

[Gokul43201]

Something simple, representation invariant and universally true, like :

** *** ***** ******* *********** *************

 

[fourier jr]

Something simple, representation invariant and universally true, like :

** *** ***** ******* *********** *************

yeah, send prime numbers, just like in that movie contact

 

[cepheid]

"The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us."

--Bill Watterson, cartoonist

 

[gimmytang]

natural constant e=2.718...

 

[gimmytang]

"The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us."

--Bill Watterson, cartoonist

maybe aliens tried to contact us through microwave 200 years ago, but at that time nobody could sense that.

 

[Chronos]

Dimensionless numbers, like the nuclear fine structure constant. That would almost surely set off alarms no matter what base system they used to count. Transmit it in binary code [on-off bits]. Even a far advanced intelligence would recognize that pattern.

 

[Gonzolo]

Yeah... like $$\pi$$ is so B.C. ...

 

[Alkatran]

Actually, I think a good start for the data you send is:
1010101010101010101010101010101010101010101010101010
followed by
11001100110011001100110011001100110011001100110011001100
111000111000
etc...

You know, so they know it's not random.

 

[dextercioby]

Euler-Mascheroni constant:
$$\gamma=:\lim_{n\rightarrow +\infty} (\sum_{k=1}^{n} \frac{1}{k}-\ln n)$$

$$\gamma\sim 0.577215665$$

Daniel.

 

[danne89]

Something simple, representation invariant and universally true, like :

** *** ***** ******* *********** *************

The problem with this it that even chimpancies can send this sequence.

I don't think pi is good neither. Think about a gas-world, like Jupiter, where solid objects don't exist in the way we know. Would they found this number without have some motivation of real circles?

 

[arildno]

Well, all sorts of exotic numbers might do, of course (for example, Brun's constant because Brun was a Norwegian..).

However, I've yet to see any suggestions simpler and more elegant than a repeating sequence of the first few prime numbers.

 

[arildno]

The problem with this it that even chimpancies can send this sequence.

ABSOLUTELY NOT!

 

[dextercioby]

WHY not,Arildno?Do you have motivation??

Daniel.

 

[Gonzolo]

I don't think pi is good neither. Think about a gas-world, like Jupiter, where solid objects don't exist in the way we know. Would they found this number without have some motivation of real circles?

There is always the Sun, and moons. I don't believe intelligent life can exist without solids. Wouldn't a zero-g ameoba tend to be round? Isn't the symmetry of a hydrogen atom round?

 

[arildno]

WHY not,Arildno?Do you have motivation??

Daniel.

That chimpanzees are likely to send a sequence of consecutive primes??
Not the ones I know about..

 

[Kahsi]

Hoenstly. Why not sending a sandwich? Who said that they want to do anything with math? If they are that smart it's like sending 1+1...They would laugh and die.

 

[danne89]

Woops. I thought it was 1, 2, 3 ...

 

[StatusX]

i think it would be really hard to send a binary signal that wouldn't just look like noise. A better way to send real numbers like pi or the fine structure constant would be to send their simple continued fraction representation. This is just a sequence of integers which could be sent in groups of pulses like the prime numbers.

 

[Kahsi]

Send the fibonacci sequense (the 100 first numbers). Or send them a swedish guy, eller hur danne89

 

[shmoe]

i think it would be really hard to send a binary signal that wouldn't just look like noise. A better way to send real numbers like pi or the fine structure constant would be to send their simple continued fraction representation. This is just a sequence of integers which could be sent in groups of pulses like the prime numbers.

Then they'd need some way of knowing your sequence of integers represented a continued fraction if you wanted them to realize it was pi. Same problem if you tried to send the decimal expansion.

My vote goes for a bunch of primes. Or if we're hoping to test their intelligence, send them the primes congruent to 1 mod 4 that are less than 200 (say). The expected response will be the primes congruent to 3 mod 4.

 

[StatusX]

Then they'd need some way of knowing your sequence of integers represented a continued fraction if you wanted them to realize it was pi. Same problem if you tried to send the decimal expansion.

contined fractions are much less arbitrary than any base system. They would know this as well as us, and even if they didn't catch on right away, I'm sure at least one alien mathematician would recognize the expansion for, say, pi.

I don't see how this would ever come up though. Would we send the signal from here? How could it possibly be found among all the other data we're constantly broadcasting? If the planet's very far away, and we send a strong signal directly at it, it would take hundreds of years to get there, and by the time the reply got to Earth we would have already built ships and gone there. Not to mention there'd be no way to get feedback if any of it was getting through. And if it was from orbit above the planet, why not just look down and see if they've got a civilization, or if that's not possible, go down there and meet them?

 

[fourier jr]

Or if we're hoping to test their intelligence, send them the primes congruent to 1 mod 4 that are less than 200 (say). The expected response will be the primes congruent to 3 mod 4.

wtf that's an even better idea. is that from contact also? i haven't read the book

 

[NeutronStar]

Which constant should we send to aliens?

I think we should send them all the irrational constants. That way we'll be rid of them and we'll only have to deal with the rational constants that we keep.

It might be a good idea to send out some imaginary constants too. You know, just in case the aliens turn out to be imaginary creatures.

 

[Chronos]

I was thinking binary code would be easily recognized. Assuming 'they' have computer technology, They surely would have used binary code at some point given the on-off switch is such a simple and natural technological approach. A signal consisting of only 2 frequencies that repeats after a long sequence should be a dead give away it is not natural. Just send a half dozen or so common dimensionless number, like pi, to a 1000 decimal places then repeat.