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Astronomers detect regular rhythm of radio waves, with origins unknown

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Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#181

Post by throw1234651234 »

gubby wrote: post #134
antepodius wrote: post #112

Earlier quoted context omitted.

Make yourself intra-universally interesting enough that the alien construction management AI might instantiate a simulation of you from the cached info at some point. It's a strange sort of Darwinism, but it's all we've got.

An instantiation of me from a backup, however accurate, would be no use to my sense of having survived as I would have ceased to exist and not even be aware of the copy.

I wonder if that's the case with "putting people on ice" if they ever manage to revive them.

Of course, one could argue that me having a past is a complete illusion anyway, as I am just some atoms.

Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#182

Post by throwaway4220 »

cheerlessbog wrote: post #147
jrichardshaw wrote: post #104

Earlier quoted context omitted.

Good question. For many FRBs there is access to the original antenna time streams (which are essentially voltages samples at 800 MHz), so superficially that might give you 1.25ns resolution. However, the intrinsic width of the pulses seem to be more like ~1ms. That tells you something about the emission source, giving you a rough upper bound on it's size of c * 1ms ~ 300km. However, lots of interesting plasma physics…

A broader question that puzzles me, not specific to this phenomenon. Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object). But it’s possible that two phenomena can be correlated without being close, if there is a delayed action (akin to setting two alarm clocks and separating them in space). How can we confidently use this as evidence of size…

> Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object).

Sorry for the possibly noob question, but why is this? I can't think of an intuitive explanation

Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#183

Post by kabacha »

__MatrixMan__ wrote: post #152
kabacha wrote: post #122

Earlier quoted context omitted.

This seems such a "flat earth" type of hypothesis. I mean viruses depend on their hosts 100% so them coming from somewhere with no hosts and successfully slotting in with new hosts just seems immeasurably unlikely.

I think it makes more sense if you think of a virus as a software update for a genome. The question is not how a virus made it here--fashioning a delivery mechanism should be easy for a civilization advanced enough to hack into the genetics of a species on a distant planet--but who are it's authors and what new features or bug fixes does it provide? Flu-like symptoms are probably just an unfortunate side effect. Thin…

But viruses don't edit our genome do they?

Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#184

Post by cheerlessbog »

throwaway4220 wrote: post #182
cheerlessbog wrote: post #147

Earlier quoted context omitted.

A broader question that puzzles me, not specific to this phenomenon. Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object). But it’s possible that two phenomena can be correlated without being close, if there is a delayed action (akin to setting two alarm clocks and separating them in space). How can we confidently use this as evidence of size…

> Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object). Sorry for the possibly noob question, but why is this? I can't think of an intuitive explanation

I guess the assumption is that the phenomenon starts at a point, spreads across the object sized l at c, and lasts for only a period of time t at any location. Therefore the pulse ends after l/c + t = T. By measuring T you can put an upper bound on l.

Example of this inference, from the Wikipedia on Fast Radio Bursts (but I have seen in many contexts):

> The sources are thought to be a few hundred kilometers or less in size, as the bursts last for only a few milliseconds

Does that make sense?

Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#185

Post by cheerlessbog »

cheerlessbog wrote: post #184
throwaway4220 wrote: post #182

Earlier quoted context omitted.

> Pulse length is often used to bound the size of a source in space (it cannot be smaller than light takes to traverse the object). Sorry for the possibly noob question, but why is this? I can't think of an intuitive explanation

I guess the assumption is that the phenomenon starts at a point, spreads across the object sized l at c, and lasts for only a period of time t at any location. Therefore the pulse ends after l/c + t = T. By measuring T you can put an upper bound on l. Example of this inference, from the Wikipedia on Fast Radio Bursts (but I have seen in many contexts): > The sources are thought to be a few hundred kilometers or less…

I just realized what I described is not giving a lower bound.

Re: Astronomers detect regular rhythm of radio waves, with origins unknown

#186

Post by Intermernet »

antepodius wrote: post #141
Intermernet wrote: post #133

Earlier quoted context omitted.

Do you happen to remember which story? I like Greg Egan and that one sounds interesting.

Found it eventually: https://outofthiseos.typepad.com/blog/files/GregEganGlory.pd... All his stories are listed here, whether they be published on his website or elsewhere: https://www.gregegan.net/BIBLIOGRAPHY/Online.html

Thanks!
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