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One quantum transition makes light at 21 cm

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Re: One quantum transition makes light at 21 cm

#161

Post by freehorse »

mannykannot wrote: post #153
wongarsu wrote: post #144

Earlier quoted context omitted.

Physics is a model of reality. Reality is objective, but the model we have chosen is very much "subjective" (maybe arbitrary is a better term). It's easy to imagine that another species might have never conceptualized electrons as little balls orbiting around a nucleus. They are neither balls nor are they flying in circles, those are simply abstractions we like because they appeal to the way we perceive reality. The…

"Arbitrary" ("existing or coming about seemingly at random or by chance or as a capricious and unreasonable act of will", "based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something" [1]) is a very poor term. Not only is physics highly constrained by what can be observed in the universe, it is also capable of demonstrating (when it is actually the case…

> is physics highly constrained by what can be observed in the universe

It is also very highly constrained by how _we_ observe the universe. Beings with different sensory/cognitive capacities could develop very different models.

> equivalences between apparently dissimilar modes of presentation

If there was some mathematical equivalence between their models and ours, which is already a leap to assume, there is still a question about whether the specific measure used would be translated to something equivalent to our object length measure in their model, which gets much stronger than just some equivalence assumption. And it’s even stronger to assume that this equivalence could just be inferred without any other information apart from the disk.

Re: One quantum transition makes light at 21 cm

#162

Post by bigiain »

adonovan wrote: post #156
mquander wrote: post #146

Earlier quoted context omitted.

If we picked up that plaque from space with an illustration of some aliens and an alien solar system and someone Tweeted it, the correct hypothesis for the numbering would develop plurality consensus within one hour. I don't know if aliens would decode it but it's not right that humans wouldn't decode it.

I highly doubt it, but it might deliver some memorable zingers about nude aliens.

And probably complaints about "wokeness" from the Galactic Twitter owner because it used a woman as the size reference...

:sigh:

I hope I never live to see Galactic Twitter.

Re: One quantum transition makes light at 21 cm

#164

Post by arghwhat »

fc417fc802 wrote: post #148
arghwhat wrote: post #135

Earlier quoted context omitted.

There is no relation between the ability to communicate and a shared understanding of our concept of quantum transitions - case in point, our invention of the technology we use to communicate with deep space far predates us learning these concepts ourselves. I'd also hold that the only thing this plaque could ever give is clear sign of artificial creation, and by virtue the (possibly past) existence of some entity ca…

> our invention of the technology we use to communicate with deep space far predates us learning these concepts ourselves. Maxwell published in 1873. The double slit experiment was 1803, subatomic theory developed throughout the 1800s, and Planck proposed quanta in 1900. The first radio transmission across the Atlantic came approximately 2 years after Planck's theory. I doubt it is plausible to develop anything resem…

The period you're describing is that of old quantum theory, which was hugely inconsistent and predates our theories of modern quantum mechanics which is post 1925 or so.

The inventor of the arc converter was 18 at the time radio waves were discovered, 34 at the time he invented the arc converter, but 56 and with only 17 years left till his death when the era of modern quantum mechanics started with the invention of wave mechanics. It's a lifetime apart.

Some discoveries were made during that period that are of course still relevant.

Re: One quantum transition makes light at 21 cm

#165

Post by damnitbuilds »

hackrmn wrote: post #103

I find it disturbing/puzzling that there is this fundamental physical behaviour like emission of light with wavelength of _exactly_ 21cm -- assuming one centimeter wasn't based on any such property but was just a "random" unit measure that stayed with us historically and through sheer volume of use (in U.S. inches filled the same niche; still do). I mean what are the odds that the wavelength is _exactly_ (the word us…

The author uses "precisely" incorrectly, which is quite surprising for an article on physics.

Re: One quantum transition makes light at 21 cm

#166

Post by arghwhat »

fc417fc802 wrote: post #149
arghwhat wrote: post #138

Earlier quoted context omitted.

Making the data fault tolerant to the discovery by another civilization, its collapse and later rediscovery by another civilization seems a bit of a stretch goal. :)

Compared to a cold object being detected and then picked up from somewhere out in deep space?

That's the "discovery by another civilization" part, so yes.

Re: One quantum transition makes light at 21 cm

#167

Post by arghwhat »

jdhwosnhw wrote: post #154
arghwhat wrote: post #114

Earlier quoted context omitted.

I sarcastically referenced the plaque itself, which is a convenient disc of a known size to anyone observing the drawing, unlike the space craft or physics riddles. Using quantum transitions is quite ridiculous in my opinion due to requiring not only the observer to have a perfectly compatible understanding of physics (even a more advanced understanding might not be compatible - maybe they don't categorize elements b…

The 21 cm line was chosen specifically because it’s the brightest line in the radio regime in our galaxy. Any civilization in the Milky Way capable of developing electromagnetic sensors would see that emission. There is a game theoretic component to this, as these other civilizations would also know that we could also see that line, and thus understand its importance

The prevalence of the 21 cm wavelength is something they would likely discover should they be in a part of the universe similar to ours. What I find laughable is the means of trying to communicate this wavelength and using it as a means to indicate our size.

Now if you go the other way, referenced 21 cm as a well known quantity (say, by making the plaque 21cm wide and referencing its diameter) and used that to describe the hydrogen spin flip in order to teach or communicate our level of physics understanding rather than depend on a shared understanding, then I'd say it makes more sense.

Re: One quantum transition makes light at 21 cm

#168

Post by arghwhat »

adonovan wrote: post #156
mquander wrote: post #146

Earlier quoted context omitted.

If we picked up that plaque from space with an illustration of some aliens and an alien solar system and someone Tweeted it, the correct hypothesis for the numbering would develop plurality consensus within one hour. I don't know if aliens would decode it but it's not right that humans wouldn't decode it.

I highly doubt it, but it might deliver some memorable zingers about nude aliens.

Not to mention that several dozen new cults formed around the plaque.

Re: One quantum transition makes light at 21 cm

#169

Post by mannykannot »

freehorse wrote: post #161
mannykannot wrote: post #153

Earlier quoted context omitted.

"Arbitrary" ("existing or coming about seemingly at random or by chance or as a capricious and unreasonable act of will", "based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something" [1]) is a very poor term. Not only is physics highly constrained by what can be observed in the universe, it is also capable of demonstrating (when it is actually the case…

> is physics highly constrained by what can be observed in the universe It is also very highly constrained by how _we_ observe the universe. Beings with different sensory/cognitive capacities could develop very different models. > equivalences between apparently dissimilar modes of presentation If there was some mathematical equivalence between their models and ours, which is already a leap to assume, there is still…

It seems disproportionate to fuss about "a leap to assume..." when we are talking about a small plaque affixed to a probe on the highly speculative basis that something intelligent might one day retrieve it, as opposed to something that is mission-critical. Would we be better off for not making these "leaps"?
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