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Tabby's star is dimming at an incredible rate

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Re: Tabby's star is dimming at an incredible rate

#111

Post by CamperBob2 »

seventytwo wrote: post #108
CamperBob2 wrote: post #62

Earlier quoted context omitted.

Safe to say that a civilization that can build a Dyson structure isn't using any 20th-century coherent modulation types that SETI could detect. SETI is only useful for catching civilizations in the ~100 Earth year-equivalent span between their development of wireless tech and information theory. There's nothing to listen to but white noise after that.

This is speculation. There are all kinds of examples we have of "ancient" technology that are still in everyday use today - knives, for example. There's no reason to think that something else would abandon using EM as a transfer of communication.

That's not what I said. Tune a general-coverage receiver to the frequency of an HDTV station, and what you hear is what the SETI folks will hear, whether there's a signal there or not.

Re: Tabby's star is dimming at an incredible rate

#112

Post by pan69 »

CamperBob2 wrote: post #107
erdevs wrote: post #68

Good ol' PV on Kinja (from the linked gizmodo article: http://gizmodo.com/the-so-called-alien-megastructure-just-go... ) has some interesting thoughts, as usual. > The biggest axe against it being an alien megastructure project is the fact its an F-type star. F-types only live a couple billion years, depending on mass. > But the drop in the radiant flux... a sustained drop. That could be something far more interestin…

I'm sorry, I must've missed something important because I've seen pointers to this post elsewhere. Who exactly is "PV on Kinja?"

I think it's a reference to the first comment on the article linked.

Re: Tabby's star is dimming at an incredible rate

#115

Post by njharman »

mkstowegnv wrote: post #110
Normal_gaussian wrote: post #86

Earlier quoted context omitted.

It also assumes that outside observers have the same difficulty understanding the make-up and probable evolution of a system as we do. If they were able to observe that Earth would have some properties they were interested in, or would be a likely candidate for such, then they wouldn't need us to announce our presence to guess it.

IMHO the aliens will not be specifically seeking life that is intelligent. Singularities and interstellar traveling alien civilizations share a problem. If one is in essence immortal the only purpose that can endure forever is the pursuit of new knowledge. Even if alien entities are able to learn all there is to know about all the other sciences, biology will be inexhaustible as the novel patterns that can be produce…

Thinking that pursuit of knowledge is only activity for immortal is naively idealistic.

Elimination of of all life not like me. Or simply eliminate life that might singularity and become a threat. Even if, who's to say one aliens pursuit of knowledge latest experiment dose not require and earth sized amount of raw materials.

Re: Tabby's star is dimming at an incredible rate

#116

Post by dredmorbius »

machrider wrote: post #85
kirykl wrote: post #80

Earlier quoted context omitted.

I understand the hydrogen line to be used tho because the noise is constant and any deviation or pattern could be easily identifiable

The problem with noise is that your signal has to be bigger than the noise in order to be intelligible. Preferably you'd find a channel with less noise, not more.

Your signal doesn't have to be bigger than the noise. But your effective channel bandwidth is limited by the signal/noise ratio:

Shannon’s channel capacity criteria for noisy channels Given a communication channel with bandwidth of B Hz. and a signal-to-noise ratio of S/N, where S is the signal power and N is the noise power, Shannon’s formulae for the maximum channel capacity C of such a channel is

C = B log (1 + S/N)

(log is to base 2)

For example, for a channel with bandwidth of 3 KHz and with a S/N value of 1000, like that of a typical telephone line, the maximum channel capacity is

    C = 3000 * log (1 + 1000)  = 30000 bps (approx.)

http://computernetworkingsimplified.com/physical-layer/relat...

On SETI's use of the Hydrogen line:

The hydrogen line (1420.40575 MHz) is the precession frequency of neutral hydrogen atoms, the most abundant substance in space. It happens to fall in the quietest part of the radio spectrum, what's known as the Microwave Window. Although there may not seem to be a lot of loose hydrogen atoms about (there's perhaps one per cubic centimeter of interstellar space), the interstellar medium contains a lot of cubic centimeters. So these individual atoms chirping away at 1420 MHz make a powerful chorus, which is readily detected by even small radio telescopes.

http://www.setileague.org/askdr/hydrogen.htm

At 1420 MHz, even with an S/N of 1/1000, you'd have about 2,048 kbaud channel, if I'm doing my maths right. Given that an intentional signal could be highly directional, this seems possible.

Re: Tabby's star is dimming at an incredible rate

#117

Post by adrianratnapala »

There is an epistamological conundrum involved in astronomy. In this case even Jason Wright admits that theories involving alien-action are

> a “perilous approach to science”—one > that could lead to an “alien in the > gaps” fallacy, and unfalsifiable > hypotheses.

But on the other hand, if we always strain to find a non-alien answer to everything we are in danger of making them up and distoring our ideas of what can happen naturally.

Re: Tabby's star is dimming at an incredible rate

#118

Post by brador »

david-given wrote: post #71
peonicles wrote: post #59

Earlier quoted context omitted.

There's a comment [1] in the other reddit thread that somewhat rules this out. > That doesn't even make sense when you're flying within the Solar System. Stuff moves, so you have to fly towards where it's going to be, not where it is. > The star is far enough away to be treated as a point source, with its light forming an apparent cone with the Earth's diameter. It doesn't intuitively make sense, at least to me, that…

You just need a big enough ship. A while back I had a plan for a science fiction setting: an inter galactic ship is approach Earth. The people who sent it thought big, and as a result the ship has at its core an enclosed star (a miniature Dyson Sphere) as a gravitational anchor and power source, and round it is orbiting a vast swarm of asteroids and habitats with a few million times the living space of Earth, inside…

Wouldn't the ship collapse under it's own gravity?

Re: Tabby's star is dimming at an incredible rate

#119

Post by erdevs »

CamperBob2 wrote: post #107
erdevs wrote: post #68

Good ol' PV on Kinja (from the linked gizmodo article: http://gizmodo.com/the-so-called-alien-megastructure-just-go... ) has some interesting thoughts, as usual. > The biggest axe against it being an alien megastructure project is the fact its an F-type star. F-types only live a couple billion years, depending on mass. > But the drop in the radiant flux... a sustained drop. That could be something far more interestin…

I'm sorry, I must've missed something important because I've seen pointers to this post elsewhere. Who exactly is "PV on Kinja?"

"PV" is a user's name on Kinja, which is the commenting system that gizmodo et al use.

Re: Tabby's star is dimming at an incredible rate

#120

Post by kalleboo »

brownbat wrote: post #65
olympusmons wrote: post #63

Earlier quoted context omitted.

Lets brainstorm. Perhaps one mathematical solution to the problem is to score pages based on the average time spent for each article. My hypothesis is that clickbait articles will score very low because the article will attract a lot of clicks from people who are not interested in the actual content but only the headline. In theory, you could do this by deploying a tracker across the web similar to a Google analytics…

There's a plugin for Wikipedia where if you hover over a linked term, it will show the first paragraph from that article, usually all you need. We just need something like that for the web.

I use QuickLook in Safari on OS X and iOS like that (OS X: triple-finger-tap to get a link preview, iOS: Force touch). It only gets ruined by those "subscribe!" full screen popups.
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