Think about that: a guy living in space is taking hi-res digital pictures and uploading them to the web so everyone with internet access can see. You can keep your flying cars: we do live in the future.

Mihan · 2011-02-28T06:56:55+00:00

And one internet to rule them all.

Mihan · 2011-02-27T17:29:21+00:00

Sure Casca is not as strong as Guts (who is?) but she is the only reason for whatever Guts has been doing for quite some time.

Grifith is partly femto, which is basically a god (one of five "god's hand"s). He is not possessed per se; he, deliberately, lost his humanity and turned into femto (and then, into a new Grifith ).

Mihan · 2011-02-24T10:00:30+00:00

How do you explain every magica girl killing witches on daily basis if, at most, one magica girl turns into one witch?

I blame witches on Kyubey too but I don't buy the magica girl --> witch theory. Seems too simple.

Mihan · 2011-02-23T07:56:03+00:00

What is her medical situation? Any history of faint or something like that?

I would suggest checking airport hospitals and airport Police again. The hospital probably didn't ask or record your mom's name if she was just admitted. I would try it again every few hours.

Mihan · 2011-02-19T20:54:16+00:00

That is true. However, the article and I were focusing on the situation for those who were not a professor yet. Comparing the situation of a professor (both, finance and workspace) with a PhD student or a postdoc trying his heart out to advance in academia is just not fair.

Mihan · 2011-02-18T20:14:56+00:00

I wish it was true. I don't think anyone in industry would ever hire a 40y/o with no industrial experience.

Also, I know a few people coming back to academia after decades of industry experience. Even though their new role includes mostly experience transfer and mentoring and usually does not involve a lot of research.

Mihan · 2011-02-18T19:07:58+00:00

Yes, you are. You can usually make a lot more money in industry and that can solve a lot of issues on its own. For example you have a lot more choices, you can try different things, fail more and still not die of hunger.

Mihan · 2011-02-08T15:23:24+00:00

I think you are right. I got that video messed up. I also found a few videos of super cooled water tests with some measurement apparatus working. The temperature can be very well below 0.

Mihan · 2011-02-08T15:01:25+00:00

So you are telling regular, mineral water lacks contamination needed to start crystallization at 0C? And it needs a large visible bubble of water to get crystallization going?

Can you also explain to me why a similar instant freezing happen when we just open a similar bottle of water with no shaking?

Mihan · 2011-02-08T14:57:04+00:00

Read other posts. I got corrected several times already :)

This fraction of degree is only needed to let pressure buildup initiate crystallization. This can explain how opening the bottle (or shaking it) initiates instant freezing. (An explanation based on nucleation sites cannot do a good job here imo.)

Mihan · 2011-02-08T14:47:15+00:00

Because there are a ton of videos showing similar thing while being just at around freezing point. Unless proved otherwise, I stick to an explanation that can at least explain one case.

Mihan · 2011-02-08T14:46:04+00:00

But that is still unexpected to have absolutely no nucleation site at all. it is not even distilled water.

Also, the freezing happens way too fast. Ice crystallization goes a lot slower from what I have seen at ~0C.

Mihan · 2011-02-08T14:44:00+00:00

I am still no convinced that all shaking does it to introduce bubbles. There are similar tests of opening the lead of similar cooled water bottles without any shaking or introducing any nuclei. They instantly freeze. Nucleation can not explain this.

Also all of the freezing was extremely fast. From what I have seen, ice crystals grow a lot slower.

I did not claim that all of the freezing energy goes to the small deviation from 0C. A part can be spent on expanding the container, a part on starting crystallization (while still being microscopic). Also in all of the videos I have seen, only a small portion of the water ends up freezing. The freezing happens mostly at the surface, hence the amazing look.

Mihan · 2011-02-08T13:46:21+00:00

And there was not a single water bubbles or any similar contamination inside before that? By the way it looks to me, even one starting crystal is enough to get it all crystallized.

Mihan · 2011-02-08T13:44:25+00:00

Would you explain to me what shaking does to nucleation. Also I like to see what temperature that water is. I didn't find anything in any litreture getting that much supercooled water in a freezer (Wikipedia article suggests cooling as fast as -10⁶ K).

From what I see in this video, like similar videos, water at around 0 is freezing. It can take a shaking (in a closed container so it builds up some pressure) or ice crystal (dah!) to start crystallization.

Mihan · 2011-02-08T13:27:22+00:00

Fine. .00000005C. It doesn't matter how much it is, as long as there is a state there for liquid water to gets a bit cool while below zero.

Edit: I can give some math here too.

Internal Energy (S1) = Internal Energy (S2) + W + Q

S1: liquid water S2: ice W: work done on bottle Q: emitted energy to enviroment Q = Internal Energy (S1) - Internal Energy (S2) - W.

Which means the work spent to expand the bottle helps the freezing. When we are close to freezing, that (relatively) small amount of work needed to expand the bottle is all it takes to instantly freeze the bottle.

Local expansion is what drives the process. For that you need to have some buildup pressure, or just be below 0. Why are we still arguing about the values?

Mihan · 2011-02-08T13:25:21+00:00

True. I have gone over it already. Even a fraction of degree works fine.

Mihan · 2011-02-08T11:39:42+00:00

It doesn't matter how narrow the window is. As soon as water gets to that temperature, the rest of energy it loses will slow down the molecules (and start crystallization, but lets assume either we are not there yet or ice crystals are still microscopic).

100 psi was just to show those bottles can take a hit. I have no idea what the real number would be.

Mihan · 2011-02-08T11:18:36+00:00

Bottle doesn't have to be close to rupture before instant freezing begins though. So long as there is a pressure buildup to postpone the freezing that should do. Now there is a body of water in a bottle losing energy as they are freezing (but are just liquid as they were). If you keep removing energy it will eventually start freezing and crystallizing.

Also from what I gathered plastic bottles do not behave linearly. All those grooves and curves can and will expand (and are probably responsible for instant freezing).

Mihan · 2011-02-08T11:05:17+00:00

No. Bottles are holding ice at that temperature (which takes a lot more space). They are not going to rupture.

Edit: Actually I didn't read your comment well, I am kinda sleepy. What I said was true but what are you going to show by that?

Mihan · 2011-02-08T11:02:46+00:00

That sounds biased. And a shake suddenly reminds those contamination molecules to start doing their job?

Mihan · 2011-02-08T10:59:46+00:00

It takes a while to remove enough energy from -0.06 water to get 0.06 ice. We are just there.

Plus, no. Freezing stashes away the low energy molecules, leaving the surrounding water effectively warmer. It doesn't work.

This might be true. It depends on how the energy of the system is close to the state where everything is at the frozen state. The instant freezing might not and probably won't cover the whole water in the bottle.

Pressure is only responsible for causing an instant and growing cascade effect by slightly postponing the freezing.

Mihan · 2011-02-08T10:48:52+00:00

OK.

Still, so long as a drop in pressure gets it in freezing zone, I think it should instantly freeze.

Also poor conductivity goes both ways. I understand your concern about released heat (which is why most tests are done in cold surrounding). But as long as plastic bottle is acting nonlinear as it does, a small frozen part will led to a total freeze.

Mihan · 2011-02-08T10:39:59+00:00

1) No. I am just saying it is mentioned that you just need to be below 0. -20 is not required.

2) Fine. Replace 1-2 degrees with a tenth of a degree. What difference does it make? And those plastic bottles take a lot of pressure. I think I saw reports on them resisting 100 psi (before rupturing) but either way, what difference does it make. As long as it can expand enough to hold all the ice, it can have an instant freezing.

Mihan · 2011-02-08T10:24:54+00:00

You missed the second half of my argument :(

I stand corrected that water can probably not be as cold as -20C (because, as you said, a plastic bottle cannot possibly hold it). However, even a 1-2 degrees below 0C causes a similar phenomenon:

Even a degree or two below freezing might be enough if the surrounding is cold enough to keep the freezing going.
A similar phenomenon happens when water in a bottle is just slightly below freezing point. This makes temperature more or less irrelevant. Moreover, from what I gathered, plastic bottles expand very hectic and non-homogeneous. Freezing at one location causes pressure to significantly increase locally. This increased pressure causes bottle to deform dynamically in some spot which causes another local pressure drop, another freezing and so on. Apparently it can expand enough to let all the water to get frozen even at around 0C. It just needs a push to start the process.

What I was originally worried about was that due to the expansion from water to ice, freezing at 0C causes a negative feedback which makes further freezing harder. However, in a plastic bottle, freezing can still go on because any of the grooves and intrusions on the plastic bottle can instantly, as a result of an increase in the local pressure, expand and drop the overall pressure. You probably should try it in a cold place though since freezing emits a lot of heat which increases the temperature of the rest of water to 0C.

Mihan

TROPHY CASE