Amateur Astronomy


#1361

There was 1 last night that lit up the sky like lightening. I was driving so didn’t see it directly unfortunately.
I saw maybe 8-9 meteors before the clouds rolled in.


#1362

Any recommendations for a documentary on Boltzmann brain?


#1363

It’s a fairly straightforward (and somewhat fanciful?) philosophical idea. Not sure you could have a whole documentary on it. I know PBS Spacetime did a video of the usual high quality, will see if I can dig it out.

EDIT: Here…

One of my objections would be to his statement at 5:25: “in the far future the universe will reach a state of maximum entropy”. The remainder of the argument is that the assemblage of a Boltzmann brain – no matter how improbable – is assured given infinite time. But I don’t think that follows.

What if the universe keeps expanding as we expect it to? Then there is no state of maximum entropy. In Boltzmann statistical terms the number of possible microstates continues to increase without end, so entropy always increases. The very low fractional probability of a BB therefore always decreases. As you know, you can sum an infinite series of decreasing fractions (or, in this case, integrate over infinite time) and get a finite sum. Therefore the probability of a BB can be finite and tiny, even in infinite time.

Another personal objection is that the BB idea entails some version of an anthropic principle, and I find that principle very unsatisfying in general for other philosophical reasons.


#1364

One of my go-to sites for digestible summaries of astrophysics papers – astrobites.org – is rapidly becoming unreadable. Woke students now report on micro-aggressions, and sign their bios with preferred pronouns. The gist of the latest summarised thesis is:

Stories and beliefs surrounding the night sky are reflections of the culture that creates them and their ideals; accordingly, the goal of this study is to look at feminine celestial bodies to understand “how the idealized role of women gets projected onto the sky and how the behavior of celestial bodies gets projected onto women” in various cultures.

I failed to spot any actual astrophysics in it. There was a helpful Google map of Africa just in case you didn’t know where it is ( – quite likely for some of these students), or that it’s a big place.


#1365

https://news.sky.com/story/signs-of-alien-life-detected-on-venus-12071625