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Jul. 19th, 2017 08:43 am
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[personal profile] seekingferret


When I heard the learn’d astronomer,
When the proofs, the figures, were ranged in columns before me,
When I was shown the charts and diagrams, to add, divide, and measure them,
When I sitting heard the astronomer where he lectured with much applause in the lecture-room,
How soon unaccountable I became tired and sick,
Till rising and gliding out I wander’d off by myself,
In the mystical moist night-air, and from time to time,
Look’d up in perfect silence at the stars.

~Walt Whitman



I first encountered this poem in high school English, and I come across it again every few years. I can't explain entirely the rage it summons in me.

But maybe this is the point I wish to make. A friend mentioned the Randall-Sundrum model of the universe and I went to that wikipedia page to try to learn what that was. Pretty soon I was desperately linkhopping- I have a basic education in relativity and differential geometry, but pretty basic, and even the vocabulary I did learn at some point, it's been a decade since and I needed to refresh my memory.

So I clicked on anti-de-Sitter space and from there to Lorentzian manifold and from there to Riemannian manifold, and I want to point out something about these four articles.

The article on Randall-Sumdrum model begins "In physics" The article on Anti-de-Sitter Space begins "In mathematics and physics." The articles on Lorentzian Manifold and Riemannian Manifold begin "In differential geometry." There's that tricksy slippage between physics and mathematics Whitman is writing about. Are the learn'd astronomer's "proofs, the figures," his "charts and diagrams" a meaningful and interesting representation of the actual stars, or are they just lifeless mathematical models that lack the "mystical" potency of observing the stars with the naked untrained eye? Aside from answering this question, though, the distinction is, I think, actually important to doing physics. Because if you theorize that spacetime takes a certain shape that can be modeled by a particular manifold, and then your measurements in an experiment don't match the manifold, you have to consider two different possibilities: One, that spacetime doesn't match your theorized model, and two, that your measurements were inaccurate. But if you're a mathematician working with a manifold and it doesn't match your expectations, only your math is wrong.

So this distinction Whitman writes on matters. There are the mathematical models of the stars, and there are the actual stars themselves, and if you forget this you end up confusing the manifold with the spacetime. A physicist needs both to do their work.

Nonetheless, I feel a great rage when I read Whitman's poem, a rage at the idea that the untrained eye bestows a more exciting and therefore truer reality than the subtle delver into the measureable mysteries of the cosmos can attain through experimentation and analysis. This may be dogmatic scientism on my part, but if so, let it be!

I made a thing...

Jul. 15th, 2017 02:06 pm
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[personal profile] amnisias
This year's Vidukon Premiere was the Norwegian Show Øyevitne - it's a 'coming-of-age/coming-out' story rolled into a crime drama, steeped in Nordic Noir story-telling. It's not actually a whodunit since we know who did it from the start, it focuses more on the 'why' and the ripple-effect of the crime as it impacts on a whole community. Some similarities to Broadchurch in that respect, I guess. The show was remade for US TV last year with some success, so I thought it would be nice to commemorate the original as well.

Streaming via youtube and download at my website.

Nate's Big To-Do List for the Weekend

Jul. 13th, 2017 06:35 pm
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[personal profile] jetpack_monkey
Please feel free to ignore:

Read more... )

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Jul. 13th, 2017 03:04 pm
seekingferret: Photo of me with my 2012 Purim beard, with stripes shaven into it. (Default)
[personal profile] seekingferret
Feel like it's worth saying that after a week in which Facebook was utterly brutal and soul-crushing, this week Facebook has been so affirming and it's worth reminding myself why I don't quit. Pictures of friends' weddings and kids and animals and summer trips. And two threads in particular on the Frum Fandom group I'm a part of: one discussing the halacha of whether Hogswarts ghosts, if Jewish, can be counted toward a minyan, and one debating whether roleplaying a character who worships the D&D pantheon is avodah zarah.

Sometimes Facebook is terrible. Sometimes it's pretty great.

CAKE :D

Jul. 10th, 2017 11:12 am
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[personal profile] lilly_the_kid
I really love cakes, I love eating them and making them and I thought I'd share some pictures. I'm going to start with a recent team effort.

A while ago a friend and I decided to try to make a Coca-Cola cake. It was easier and turned out better than we imagined.





It was a bit tricky to get it out of the plastic. I had an xacto-knife which worked quite good. We just needed to put the cake back into the fridge for a while, because the chocolate would melt when we were holding/touching it for too long.

It turned out great, though and it even stood on its own. And it tasted amazing!!


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