RIP

[sdbardwick]

Christopher Columbus Kraft Jr.

[kladner]

Ah yes. Chris Kraft. I was always amused by the homonym-named boat company, Chris-Craft.

[tServo]

Rutger Hauer

Actor whose most famous role was probably Roy, one of the replicants Harrison Ford was hunting in "Blade Runner"

He is said to have altered his ending monlogue:

“I’ve seen things you people wouldn’t believe,” Roy says. “Attack ships on fire off the shoulder of Orion. I watched C-beams glitter in the dark near the Tannhäuser Gate. All those moments will be lost in time, like tears in rain. Time to die.”
http://www.indiewire.com/2019/07/rut...in-1202160606/

[Dr Sardonicus]

Russi Taylor

[xilman]

Nilolai Kardashev

[ewmayer]

Originally Posted by xilman

Nilolai Kardashev

As it happens Contact was on the BeebAmerica cable channel last night ... Kardashev would've been disappointed that the Hollywood aliens in the film used something as prosaic as the primes up to 101 to convey their presence. Sending the exponents of all Mersenne primes known to them would be a much better way to both announce one's presence and convey the level of technological sophistication of one's society.

Of course in Contact once the small primes are dispensed with, things ecalate immediately to a full TV back-broadcast of Hitler opening the 1936 Berlin Olympics, and sekrit blueprints for building your own DIY spinning-ring-thingie backyard wormhole generator. So I guess the tech-level becomes pretty obvious that way.

[xilman]

Originally Posted by ewmayer

As it happens Contact was on the BeebAmerica cable channel last night ... Kardashev would've been disappointed that the Hollywood aliens in the film used something as prosaic as the primes up to 101 to convey their presence. Sending the exponents of all Mersenne primes known to them would be a much better way to both announce one's presence and convey the level of technological sophistication of one's society.

Of course in Contact once the small primes are dispensed with, things ecalate immediately to a full TV back-broadcast of Hitler opening the 1936 Berlin Olympics, and sekrit blueprints for building your own DIY spinning-ring-thingie backyard wormhole generator. So I guess the tech-level becomes pretty obvious that way.

I disgree with your second sentence. Small primes are a simple way of drawing attention; instantly recognizable yet having low information content. As you point out, the complicated stuff can come later once the intended recipients have realized there is a message in the raw data and then becomes worthwhile spending a great deal of intellectual effort decoding what looks at first glance to be random noise.

A lot of bright people, Sagan included, have thought deeply about such things.

[Dr Sardonicus]

Toni Morrison

[ewmayer]

Originally Posted by xilman

I disgree with your second sentence. Small primes are a simple way of drawing attention; instantly recognizable yet having low information content.

Why would you want low information content - state secrets? Both sequences start with the same instantly-recognizable 2,3,5,7 ... one just gets interesting and nontrivial rather more quickly than the other. Even if the start somehow gets garbled in transmission (of course one would re-transmit endlessly, but assume a scenario where only an occasionally small fragment gets through), the 2-number fragment "25964951,30402457" is going to tell you more than, say, "31157947,31157953".

But I suppose the sheer tedium of ascending primes contains a lot of redundancy-via-inference; perhaps that is desirable precisely on "noisy medium" grounds - I was arguing from most-info-content-in-fewest-bits grounds.

[kriesel]

Originally Posted by ewmayer

Why would you want low information content - state secrets? Both sequences start with the same instantly-recognizable 2,3,5,7 ... one just gets interesting and nontrivial rather more quickly than the other. Even if the start somehow gets garbled in transmission (of course one would re-transmit endlessly, but assume a scenario where only an occasionally small fragment gets through), the 2-number fragment "25964951,30402457" is going to tell you more than, say, "31157947,31157953".

But I suppose the sheer tedium of ascending primes contains a lot of redundancy-via-inference; perhaps that is desirable precisely on "noisy medium" grounds - I was arguing from most-info-content-in-fewest-bits grounds.

You want redundancy in the bit stream, for noise resistance, and a conspicuous pattern that would not be expected to occur naturally.

So how many Mp exponents to broadcast, and how much priority does that add for double-checking? What are the odds their SETI equivalent has even heard of (whatever they call) Mersenne primes, compared to having heard of general primes? I do not have the impression that random sampling of earth's scientists would reliably yield Mersenne prime awareness in a room of 30 occupants. In 35 years of working with scientists, I don't recall the topic ever coming up.

The Kardashev scale seems a bit coarse to me for indicating technological level of a civilization. From our own historical experience, some significant milestones were
use of animal muscle power
use of water and wind power
use of combustion engines
controlled fission
(maybe someday) controlled fusion breakeven
Of course most of these are hard to detect from astronomical distances, while capture of energy of a star or larger sector is likely to have a big signature.

[xilman]

Originally Posted by kriesel

The Kardashev scale seems a bit coarse to me for indicating technological level of a civilization.

The scale is generally interpolated on a logarithmic scale.

I've seen our present civilization given a rating of K0.8, for example.