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Devac




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Devac  ·  link  ·  parent  ·  post: Pubski: May 15, 2019

I'm glad you found it interesting, though real wisdom manifests as at least double-checking any chemistry you'll find on the net, common sense, and staying on the side of caution. In the case of soap-making, it basically boils down to watching out for splashes, having some eye protection and keeping it away from aluminium (reacts to produce hydrogen gas). Lye will also affect wood, so it's best to do the entire process in/with glass, ceramic or resistant plastic implements and containers, aim for sturdy. Also, here's one lesson I learned three minutes too late a few years ago: dissolving lye can make your solution hot enough to significantly deform PET bottles, up to the point of making small cracks, even though it doesn't react chemically with it.

That said, if you have questions or would like to know more, feel free to ask here or via private message. It's a fun project with plenty of room for experimentation, so I hope I didn't discourage anyone.

Devac  ·  link  ·  parent  ·  post: Pubski: May 15, 2019

Making basic soap is fairly easy, and ingredients are widely accessible: lye (sodium hydroxide), oil (olive, coconut, any will do but will affect hardness) and water (distilled/deionized). 80g lye, 200g water (distilled/deionized <- this is very important for boring chemistry reasons), 100g of coconut oil, 500g of olive oil are great as a starting base because it's close to most of the store-bought soaps while having an excess of oil (meaning you don't need to worry too much about pH or purify it further). Add lye to water, mix with oils until you'll get a consistency of thick batter (this is when you can put dyes or essential oils or other optional additives, like salt, poppy seeds or antibacterial compounds based on silver), drop into moulds and wait about a day or two. Afterwards, remove from moulds and put somewhere to dry, flip sides about once a week. Waiting time varies and depends on humidity and bar sizes, but it tends to be around five weeks. The smell during production isn't too much of a concern or problem, though I might be desensitised to odd chemical odours.

I wouldn't fuss with making my own soaps if it wasn't oddly fun, though. There's still about a fifth left from the batch I made in autumn, which is kinda comforting: no matter what, there's some soap left. ;)

Devac  ·  link  ·  parent  ·  post: Pubski: May 15, 2019

Between price and ingredients, I'd rather make my own than buy. Either way, thanks. I'll try it when possible.

Devac  ·  link  ·  parent  ·  post: Pubski: May 15, 2019

I applied for a bunch of research-centred PhD programmes/positions that aren't directly tied to universities. There are surprisingly many of those posted by various governmental agencies looking for physicists, definitely more than what I saw last year, which is one of few good surprises I had over the last few months. This weekend I'll start working on submissions to the Polish Academy of Sciences and similar institutes, which is painstaking, but hopefully worth all the years of effort. That's where I'd like to end up working anyway, but it's best to cover as many bases as possible.

Had to double my hours at the carwash to make sure I'll have enough money for this summer, which is starting to take its toll. I'm fairly certain that I developed some sort of skin allergy to the crap we handle, but it's not like I'm in a position to look for something better. At least this time I planned things in such a way that I might catch some break around August, so that's nice.

Also, Organic Chemistry is the only course I ever took where my grade from labs is significantly better from theory. Feels weird.

Devac  ·  link  ·  parent  ·  post: First Ever Images of a Black Hole

Don't listen to whatever they say, the astro estate bastards never mention mortgage accretion.

Devac  ·  link  ·  parent  ·  post: Pubski: May 1, 2019

Well, to be fair to them, they were helpful. They made my CV more readable, helped me select a picture where I don't look like a complete spazz, gave me tips on (body) language, and made me realise a couple of things that I'm often too dense to notice in time while talking to people. But that's just about the crux of it: I'd be a terrible civil servant in just about every regard imaginable, and it shouldn't take more than an hour to ascertain that. They had twelve.

Devac  ·  link  ·  parent  ·  post: Pubski: May 1, 2019

I've been refreshing what little I learned about JavaScript by writing utility bookmarklets. It's nothing you wouldn't find on the Internet already (open current page's copy on archive.org, list all outbound/inbound links, rotate/blank/whatever all images etc.), but now there's at least some purpose behind it, which makes all the difference. Much to my surprise, it's actually a lot of fun.

The recent weeks were hectic, and the few days I got now are my island of downtime until graduation, which is likely to happen sometime in the middle of June. Can't wait for that, though it's a paradise compared to the idea of going through job search bullshit while applying for doctoral programmes on top of it. At least I decided it's physics instead of maths, and I'm not moving from where I am; six relocations in four years were enough.

That uni place that's supposed to coach me for job interviews changed from "talk to us, we're listening and it's completely about finding a solution through dialogue and exercises" to "shut up, will ya? here's a thirty-minute-long diatribe on why we think you're Civil Service material, disregard your objections about complete lack of relevant skills or background this instance!" within three weeks. At least it's a decent excuse to meet people from humanities campus, which is a very different place, but I don't know if I'm going to continue to bother myself with that thing for much longer.

    astronomical units (AU) isn't in the selection menu?

It's there, though. At the 'scientific' section, they just didn't capitalise it and it's 'au'.

    anything practical you mentioned

Absolutely true, but if goobster could brush me off on pointing out that teleporting ~10^29 particles composing the human body would be beyond stupidly difficult and doesn't-work-like-star-trek (source), I assumed that anything optimistically achievable within 100 or so years is fair game. :P

If you want to go really big, put a telescope at the focal point of Sun's gravitational lens, which is about 550 AU from it. The project is called FOCAL.

Devac  ·  link  ·  parent  ·  post: Cosmology Has Some Big Problems

Oof, I'd have to find those notebooks to be certain, but, logically, initial inflation would have to be a lot slower and happen later in the universe's evolution to accommodate this model. Presumably, the observable universe would be smaller than what we can observe, but that doesn't need to be the case, just something that I find likely to be one.

What I do remember is that we did a cluster dynamics simulation[1] starting with standard initial conditions (matter starts randomly positioned on a sphere, mass distribution of 'chunks' is logarithmic and something about the distribution of initial velocities that I can't recall but will probably add in an edit) and the end result lacked those bubbles surrounded by supercluster filaments you get with dark matter (which, in fact, do exist).

That said, I'll try to find those notes, if only because I don't like to second-guess my memory.

[1] - Reasonably smaller scale than the ones you can do on a proper supercomputer. IIRC, we were constrained to 128 GB memory and only got allocated 50 hours on uni grid.

Devac  ·  link  ·  parent  ·  post: Cosmology Has Some Big Problems

I really like this article. It's refreshing in that it doesn't yammer on about MOND Saving the Day™ while remaining healthily sceptical and informative.

Recalling one of the multi-week problems we were assigned during the General Relativity II, you can reasonably easily extend GR to derive a model of the universe without dark matter by 'simply' assuming that the flow of time measured by an observer has to be indistinguishable from a locally flat universe. When you check for (rotational) velocity dispersion function in such a model, it will be consistent with observations, provided you consider motion with respect to the CMB. However, as a consequence, it will turn out that the age of our universe is a couple of billion years older (16 or 17 IIRC, it depends on energy-mass density), which – to my knowledge – isn't easy to reconcile with other observations.

There's not much point to those ramblings, however, problems like those make me very happy I went for condensed matter instead of cosmology. :P

No doubt applewood will elaborate and drop better resources, but what surprised me was how local populations of wolves and their prey skyrocketed in nearby areas. Wildlife is thriving there, oddly.

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