# Which constant should we send to aliens?

1. Jan 24, 2005

### danne89

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

2. Jan 24, 2005

### Ryoukomaru

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

3. Jan 24, 2005

### master_coda

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

4. Jan 24, 2005

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

5. Jan 24, 2005

### Alkatran

e^(pi*i) + 1 = 0

6. Jan 24, 2005

### WORLD-HEN

You could send them a golden rectangle.

7. Jan 24, 2005

### Gokul43201

Staff Emeritus
Something simple, representation invariant and universally true, like :

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

8. Jan 24, 2005

### fourier jr

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

9. Jan 25, 2005

### cepheid

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

--Bill Watterson, cartoonist

10. Jan 25, 2005

### gimmytang

natural constant e=2.718...

11. Jan 25, 2005

### gimmytang

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

12. Jan 25, 2005

### 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.

Last edited: Jan 25, 2005
13. Jan 25, 2005

### Gonzolo

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

14. Jan 25, 2005

### 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.

15. Jan 25, 2005

### dextercioby

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

$$\gamma\sim 0.577215665$$

Daniel.

16. Jan 25, 2005

### danne89

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?

17. Jan 25, 2005

### 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.

18. Jan 25, 2005

### arildno

ABSOLUTELY NOT!

19. Jan 25, 2005

### dextercioby

WHY not,Arildno???Do you have motivation??

Daniel.

20. Jan 25, 2005

### Gonzolo

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?