Looking at faraway stuff - The Bear and Badger

Armitage_Shankburn

SpaceGazelle wrote:

Mars is out and looking good in this heat.

It's a real treat at the moment. Jupiter dominating before dusk even, like a second distant moon. Saturn dimmer and not as close. A few days ago, a full blood red moon thanks to the Sirocco, at the time.a delightful sight but a harbinger of insufferable heat to come. And to its left, unmistakable, a red undimming, low presence, had to be Mars and it was..think that was Friday.

Perseids tonight. iSS saying hello while I wait. Think I need to get myself off to somewhere high next summer.

Scout

I got an Instagram ad yesterday for some kind of super-duper mega monocular capable of seeing Saturn in all its ringed glory. And it was only like 100 dollars. Complete bullshit?

Dinostar77

Yep

Armitage_Shankburn

its true, all of it

Spoiler:

.

but seriously, no idea

SpaceGazelle

Probably but maybe not. The biggest problem is resolution not magnification and this requires a big mirror, and there's no getting around how costly they are to produce.

Can't quite remember but Hubble magnification was tiny (3x?) because it's not important. It's the amount of light collected that's important and that's going to cost in something so precise as a telescope mirror. No doubt machine learning will help but I don't know if they're using that right now.

SpaceGazelle

Btw Muzzy you should get into machine learning in your spare time. The concepts are stupid easy to understand but the results are unbelievable.

It's just a matrix of randomly initialised weighted numbers. The weights are adjusted as each training instance is fed in using differentiation to lower the mean squared error. It was invented decades ago but it took GPUs (and a few clever tweaks to stop the gradients tending to zero as it is trained) to get to work.

Google has a free course. As a maths guy you'll ace it.

SpaceGazelle

Oops wrong thread.

Lord_Griff

Dinostar77 wrote:

This is a good read, a countdown to the 50 strangest objects in the universe.

https://astronomy.com/tags/weirdest-objects

Nice find. Thanks.

b0r1s

I haven’t read it, I probably won’t understand it, but we may have solved the black hole information paradox, according to Coxey.

https://arxiv.org/pdf/1905.08255.pdf

Might be a fun read for some of you.

Diluted Dante

Oh a magic door, why didnt you say so.

b0r1s

Wouldn’t know. Haven’t read it.

SpaceGazelle

I didn't even understand the abstract. If anybody is wondering why information can't be lost it's because the universe has to have a way of getting back to a previous state (sort of time-reversal) and it can't do that if it has lost some info. If stuff disappears for good then the universe can't 'remember' say, how much energy it had and that would cause it to break.

Armitage_Shankburn

Is that why I keep finding old 50p coins in the sofa?

SpaceGazelle

Pretty much.

acemuzzy

the universe has to have a way of getting back to a previous state

Says who? And why?

SpaceGazelle

Because the arrow of time doesn't have a direction as such, except the second law of thermodynamics, but that's not a law as much as a statistical phenomena. While it's highly unlikely, there's no law stopping your melted ice cube from reforming, and if there were that would be a problem.

SpaceGazelle

Actually that's not quite true, it's about the progression (forward and backward) of the wave function and the quantum state, but I was trying to find a loose analogy.

SpaceGazelle

If you corrupt the future quantum state of an object you also corrupt it's past. That's probably the best way of saying it.

bad_hair_day

SpaceGazelle

The drummer is the bestest.

acemuzzy

I don't really understand what you're saying. Maybe I've had too much caffeine. Doesn't e.g. a collapsing wave function implicitly lose information?

SpaceGazelle

It depends on the interpretation to an extent and the many worlds avoids this nicely, but even with the Copenhagen view this is avoided. A bit.

You can't experimentally show this to be the case, that the info is lost. This sounds trivial but it's not. The observer influences the system from the outside and there's plenty of room to have the info stored instead in the outside party. Whether this is true or not is up for debate.

Much of this is interpretation dependent. Many argue there is no information at all until something is observed but once it's out there it must stay out there. It's a difficult topic.

Vela

acemuzzy wrote:

I don't really understand what you're saying. Maybe I've had too much caffeine. Doesn't e.g. a collapsing wave function implicitly lose information?

Resolves it, is possibly a better term than lose it.
The information was there before, now it's in a different state.

SpaceGazelle

I think generally nearly all physicists implicitly believe there's no info loss because it would make some subjects very difficult. It would certainly indicate a true direction of time and that raises a whole load of new questions and would require some new physics. Not impossible but probably revolutionary.

Dinostar77

Trending on Twitter, maybe bullshit. But some people are suggesting there will be an announcement on the following:

"Phosphine signature found in the atmosphere of Venus.
Phosphine is a strong biosignature gas, as it has no known abiotic false positives on terrestrial planets from any source that could generate the high fluxes required for detection.
Source: MIT"

SpaceGazelle

Link?

b0r1s

Check the tin foil thread.

SpaceGazelle

No thanks. It's gotta be bullshit.

Dinostar77

http://astrobiology.com/2020/09/phosphine-detected-in-the-atmosphere-of-venus---an-indicator-of-possible-life.html

SpaceGazelle

They've only recently discovered phosphene can only be made by anaerobic life and all of a sudden it's found on Venus? Mmmmm

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