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SETI scientists to devise plan for lunar listening station

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Re: SETI scientists to devise plan for lunar listening station

#81

Post by jmyeet »

exitb wrote: post #80
jmyeet wrote: post #74

SETI is not how we'll find alien spacefaring civilizations. Within 1000 years, barring some apocalypse, an incredibly conservative prediction is that we will be able to build permanent space orbitals. We already have sufficiently strong and readily available materials (ie stainless steel) to build O'Neil Cylinders at 2-4 miles in diameter and 10-20 miles in length that could house as many as a million people. These c…

What would be the motivation to build those cylinders? Traditionally people ventured into new places in hope of getting return of the effort and cost of the journey. Here it seems like you need to invest a lot, just to survive in emptiness.

The amount of energy you would have access to is almost unimaginable. We can only speculate what you'd do with that but two leading ideas are:

1. It may well be the only feasible method of interstellar travel. Accelerating a spacecraft is a whole bunch of fuel you don't have to carry; and

2. Computing power.

So what would motivate people? Living room. One estimate I've seen is the current population of Earth on a full Dyson Swarm would give each person the equivalent living space of the continent of Africa. Of course you'd probably have a ton more people. It's likely you'd have a quadrillion people (>10^15) with each person having significantly more room than they do on Earth.

Re: SETI scientists to devise plan for lunar listening station

#82

Post by andyjohnson0 »

bnralt wrote: post #15
miika wrote: post #14

I doubt SETI could detect even our own signals, when it’s encrypted digital data. I mean it’s just noise like any background signal.. Then, we people are very soon capable of communicating using quantum entanglement, which means it’s beyond wireless and you simply couldn’t tap into it with some antenna. For these reasons I suspect that SETI is waste of money.

Yeah, the SETI Institute's site says we wouldn't be able to pick up signals from an earth like civilization in the system closest to us[1]: > If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth? > In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some impor…

> the SETI Institute's site says we wouldn't be able to pick up signals from an earth like civilization in the system closest to us[1]

TO be clear, the signals it is referring to are those that would be similar the unintended leakage of normal broadcast and military radar systems used on earth. So detecting ETIs from their passive emissions is certainly unfeasible that the moment.

Signals broadcast by a hypothetical extraterrestrial civilisation as part of an intentional seti signalling effort would (presumably) use much higher power, narrower bandwidth, and frequencies chosen to reduce attenuation by the interstellar medium. These would be detectable using our current technology, and is largely what seti is looking for.

Re: SETI scientists to devise plan for lunar listening station

#83

Post by edf13 »

bombolo wrote: post #59
epicureanideal wrote: post #52

Earlier quoted context omitted.

You could flip the coin at different time intervals like short and long dashes in Morse code.

You're still flipping a coin… how is this communication?

Don't you simply read the state of the other entangled coin?

Heads = 1, Tails = 0?

Re: SETI scientists to devise plan for lunar listening station

#84

Post by TechBro8615 »

p-e-w wrote: post #39
TechBro8615 wrote: post #29

Earlier quoted context omitted.

> we cannot use effects related to quantum entanglement to communicate ELI5 to a non-physicist why not? I thought this was possible, if Alice and Bob share an entangled pair of a set of particles (i.e. each has a clique of particles entangled with the other), and they pre-arrange an algorithm for determining the meaning of different states of their particles. IIRC wasn't this the gist of the "wormhole" paper that wen…

Quantum entanglement means that pairs of particles can have correlated states regardless of the distance between them. It does not mean that if you push on one particle, the other one lights up. Imagine that two people are each given a coin with the property that whenever they flip those two coins simultaneously, they will either both come up heads, or both come up tails. How can you use that to communicate , that is…

But if each side of the pair can only have a certain number of states, is it not possible to perturb one of them until it gets into a state such that you know based on entanglement that the other must be in its corollary state?

Re: SETI scientists to devise plan for lunar listening station

#85

Post by johncolanduoni »

epicureanideal wrote: post #52
p-e-w wrote: post #39

Earlier quoted context omitted.

Quantum entanglement means that pairs of particles can have correlated states regardless of the distance between them. It does not mean that if you push on one particle, the other one lights up. Imagine that two people are each given a coin with the property that whenever they flip those two coins simultaneously, they will either both come up heads, or both come up tails. How can you use that to communicate , that is…

You could flip the coin at different time intervals like short and long dashes in Morse code.

The analogy is imperfect: with quantum states you cannot tell whether the other person performed a measurement or not.

Re: SETI scientists to devise plan for lunar listening station

#86

Post by prai1SE »

p-e-w wrote: post #32

While I do share a certain romantic admiration for the grandeur of SETI's goals, I have to agree with those who call this a waste of money and brainpower in our times. The most ludicrous AGI apocalypse scenarios seem orders of magnitude more likely than finding conclusive evidence of extraterrestrial intelligence. A second terrestrial intelligence is about to emerge, and the consequences of that might conceivably be…

I think there is value in having this proposal written and published.

Even if it does not get built anytime soon (say because today‘s society thinks this is a waste of money), having the idea discussed in public helps and might inform future decisions.

For example, we still reread proposals like the Dyson sphere, space elevators, a next-gen LHC, etc. . None of this is either technologically feasible today nor realistically fundable, but it shows the ambition and might spark discussions.

Re: SETI scientists to devise plan for lunar listening station

#87

Post by bradrn »

edf13 wrote: post #83
bombolo wrote: post #59

Earlier quoted context omitted.

You're still flipping a coin… how is this communication?

Don't you simply read the state of the other entangled coin? Heads = 1, Tails = 0?

You have no control over the resulting state, though. In this analogy, if you have two entangled coins, all you know is that if you flip the coins at the same time you get the same result… you don’t have any control over what that result is, and unless you arranged it with them beforehand you don’t know when the other person flipped their coin.

Re: SETI scientists to devise plan for lunar listening station

#88

Post by bshipp »

scrollaway wrote: post #49
p-e-w wrote: post #46

Earlier quoted context omitted.

> starting to question the gain of a project in the scientific space is never really an argument It most certainly is, at least in the real world. The ISS has cost more than $150 billion so far. That's not "a joke", it's the GDP of a mid-size country. I very much do hope that everyone involved is asking themselves hard questions about whether this expense is justified by whatever has been gained in return. Science is…

> The ISS has cost more than $150 billion so far. Wow, a whole three "midlife crisis ceo twitter buyouts".

It'd be cathartic if our kids referred to a gigantic financial blunder in the billions of dollars as pulling an "Elon".

Re: SETI scientists to devise plan for lunar listening station

#89

Post by johncolanduoni »

TechBro8615 wrote: post #84
p-e-w wrote: post #39

Earlier quoted context omitted.

Quantum entanglement means that pairs of particles can have correlated states regardless of the distance between them. It does not mean that if you push on one particle, the other one lights up. Imagine that two people are each given a coin with the property that whenever they flip those two coins simultaneously, they will either both come up heads, or both come up tails. How can you use that to communicate , that is…

But if each side of the pair can only have a certain number of states, is it not possible to perturb one of them until it gets into a state such that you know based on entanglement that the other must be in its corollary state?

Given only an entangled qubit, the only thing you can do that will be “synchronized” with the other party is perform a measurement. Each measurement performed by either party will produce either a 0 or 1 without any “input” from the measurer or the other party. Any perturbation of the state that preserves the entanglement can only rotate it (which just alters what state your side considers 0 and 1).

Re: SETI scientists to devise plan for lunar listening station

#90

Post by TechBro8615 »

johncolanduoni wrote: post #89
TechBro8615 wrote: post #84

Earlier quoted context omitted.

But if each side of the pair can only have a certain number of states, is it not possible to perturb one of them until it gets into a state such that you know based on entanglement that the other must be in its corollary state?

Given only an entangled qubit, the only thing you can do that will be “synchronized” with the other party is perform a measurement. Each measurement performed by either party will produce either a 0 or 1 without any “input” from the measurer or the other party. Any perturbation of the state that preserves the entanglement can only rotate it (which just alters what state your side considers 0 and 1).

Thanks. While you were writing your comment I found this article [0] that does a decent job of explaining why my hypothetical system isn't possible. It first lays out the exact system I had in mind and then unfortunately debunks it :(

I don't fully understand the subtleties, but the root problem seems to be that by measuring the state, you're perturbing the system and putting it into a new state, such that your measurement becomes irrelevant, as if you're always one step behind the message and can never catch up.

> The only way that this problem could be circumvented is if there existed some way of making a quantum measurement that actually forced a particular outcome. (Note: this is not something permitted within the presently-known laws of physics.)

[0] https://bigthink.com/starts-with-a-bang/quantum-entanglement...

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