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Comment Re: Well done... (Score 1) 292

I agree with the units issue. The American pre-distribution NG sectors work in standard cubic feet (where standard is usually but not always 15C and 1 atm). Sometimes they work in standard liters. In Europe they frequently work in normal cubic meters.

If I were reporting this, I would give units of cfh and btu/hr. Btu is what a person is actually paying for.

Comment Re:Fast fish and loose fish (Score 2) 239

Thermoses, also known as vacuum flasks, work because there is a vacuum gap between inner and outer walls. This includes liquid nitrogen and helium dewars.

The blackbody emission power is independent of the environmental temperature. The 3 K in space is irrelevant to the amount of power that the metal will emit. If you're referring to the radiation that the metal would have otherwise absorbed in a warm environment, keep in mind that the Stefan-Boltzmann law goes as T^4. The amount of radiation lost by the really hot metal will be far more than the energy is absorbs from the surrounding environment, unless the environment is close in temperature to the metal.

More importantly, who says that molten metal is a good blackbody? The principle of detailed balance tells us that if a surface doesn't absorb much radiation, it can't emit much radiation. In terms of blackbody emission, that translates to an emissivity that changes depending upon reflectivity. Polished copper has an emissivity of 0.03 at 1.6 microns, meaning it will emit 3% of the amount radiation that a blackbody would at the same temperature (@ 1.6 microns). Molten iron has an emissivity of 0.35 @ 1 micron (red hot).

If you want to keep your molten metal hot in space, put it into a shiny box (oven) for it to cool. I just did a quick calculation for a 50 cm dia sphere of 1900 K molten iron in deep space. It would take 104 hours to cool to room temperature if it was floating in free space (although it would drop to 1000 K after the first 4 hours). If you put it into a polished platinum box (emissivity of 0.02), it would take weeks to cool off.

Comment Re: "Expected" to release methane (Score 1) 329

Closer to 35 times better (on a 100 yr horizon):


Agreed, CO2 and CH4 going into the atmosphere are both bad. CO2 just isn't quite so bad.

Good point regarding acidity. Now I need to do the calculation of pH increase as a function of X megatons of CO2 evolution in the ocean.

Comment Re: "Expected" to release methane (Score 1) 329

There's also a lot of unknowns about whether the CH4 even makes it to the surface. There's a lot of microbial activity between the sea floor and surface that loves to eat methane and release CO2:



Tons of CO2 is a lot better in the atmosphere than tons of CH4.

Comment Re:I don't want to precipitate an argument, but .. (Score 1) 36

I'm not the one calling your words scum or dross. It's a legitimate question that I'm responding to. I have in fact thought about the implications of a lack of gravity upon chemical reactions, which is why I pointed out the few cases where it would be important. For homogeneous reactions (which are central to biochemistry), I encourage you to calculate the force of gravity, compared to local electrostatic forced such as dipoles and bond dipoles.

I agree with what you're saying that precipitation reactions will be affected by lack of gravity, as I repeatedly pointed out when I refer to biphasic reaction and phase-related reactions.

Comment Re: FYI: line one of abstract (Score 1) 36

I maintain the assertion that the number of reactions that are affected by gravity very few and far between. In fact the last sentence of that abstract contradicts one of the few examples that claimed to observe effects of weightlessness.

Just thinking about this physically, the forces associated with electrostatic interactions and molecular diffusion are many orders of magnitude larger than that of gravity. Gravity is not relevant on the molecular scale. Any effects that may be relevant would be associated with differences in solvent flow or phase-related reactions.

Comment Re: Will this go the same way as the spintronics? (Score 1) 36

"reaction rates etc differ without the shear force from gravity and it hasn't been looked at much yet."

[citation needed]

  I'm a chemist, and I have yet to see a case where gravity plays a measurable role in standard single-phase chemical reactions. Yes, it may play a role in bulk biphasic reactions. But in a standard liquid-phase biochemical reaction, local diffusion forces (collisions) will overwhelm gravity. In addition, most biochemical reactions are stirred to maximize contact between reagents further reducing the effects of gravity.

You may be able to find a reaction or two that is affected by gravity, but those will be a few and far between.

Comment Re: Fair-weather power sources are lame... (Score 1) 337

Something I'm wondering about is why the batteries that the panels are recharging can't be intermittently charged for 1.5 hours every 12 hours until they're full again. At that point could they just fire Philae back up and run it until it's out of juice again? Solar chargers on earth are capable of this as long as there's not an external drain on the batteries.

So basically why can't Philae run with a X% duty cycle, where X is some number less than the 100 they were hoping for?

I'm sure there's a good reason why that won't work (is there an external drain?) but does anyone here know why?

Comment [citation needed] (Score 2) 145

Not that I don't believe it, but the only link in the story that directly refers to the explicit ban is a picture of an email that one guy sent to another. It says that he likes working at sugarstring, but spying and net neutrality are verboten topics.

Anyone have a contract or other bit of more concrete evidence? Or is this story solely based upon the image of an email?

Comment Re:My God... (Score 1) 458

I agree with all your points here. It seems like the "standard picture of inflation" curve is the crux of everything, and is referred to repeatedly. But he doesn't even define the axes well. (I agree with your complaint about the axes - he says the y-axis is energy, but the x-axis is specifically in units of energy).

I'm unclear on one apparently critical point that maybe someone can clarify. I see what he's saying that the universe dominated by vacuum energy expands much more quickly than one dominated by radiation or matter. But does this mean that it's expanding faster the the speed of light? It seems to me that he's saying the multiverse happens because there are these pockets within the multiverse of slow expansion (an individual universe within the "well") and fast expansion in between, right? But then the only way those pockets could not be observable between each other is if the "fast expansion" region is faster than light. Why does the fact the the expansion doesn't slow down in a vacuum dominated universe mean that certain parts of the universe are out of reach of other parts. Is gravity the culprit here?

Part of this comes down to his equation(s):

size ~ t^n, where n = 2/3, 1/2, or 1

First of all, what is "size"? Volume? Length? Area?

Second, and most importantly, why isn't that expansion rate linear in time for everything. What is it about the physics that makes a matter dominated universe expand differently than a radiation-dominated universe? Is that easy to explain? And if so, that's crucial for my understanding here.

Something that's never been clear to me in the expanding universe model is why the expansion of the universe results in red-shifting of light and shifting of the CMB to the microwave region. Can someone explain this? If the expansion is of space itself, which I interpret as the "grid" upon which matter/radiation exists, how does light or anything else know that the grid is expanding? In the silly picture in my head, I'm thinking that I won't know that my ruler is changing length since I'm changing length with it, just like how person A moving at near the speed of light relative to person B doesn't know that the space that they're in has "shrunk" according to person B. In the model of the expanding balloon with ants on the surface, how do the ants know that the expansion is occurring? If I were one of the ants, I'd draw a grid around me out to the next nearest ant. As the balloon (universe) expands, the grid would expand with it, so I would have no idea that the next ant is getting further away. Why is it different in the universe expanding? Is it just radiation that knows of the expansion? I'm clearly missing an important concept, but I don't know what it is.

Comment Re:Is it a "Vaccine" or a "Cure" (Score 1) 72

Not sure why this is a troll, but I wish I had mod points to bump it up. I'm not the OP, but I was wondering the same thing regarding how this was a vaccine. This explanation makes complete sense and thanks for the clarification.

Just so I'm understanding correctly: the amount of HIV virus in the blood is very small after initial infection, so the idea is to use the vaccine to keep the level low (i.e. prevent the virus from ever ramping up again and destroying your immune system)?

So this would prevent infection for those without HIV, and keep HIV dormant for those that already are infected?

Comment Re: not surprised at racism and naive WASPs (Score 2) 1737

To follow up on that: jurors are not selected randomly. The defense and prosecution pick from a larger set of jurors. What are the chances all jurors would be female? That is 1.6% but not a coincidence. The prosecution surely would have gotten a couple of black people on the jury if they thought they had a solid race argument. Rather they opted for the female/mother angle ("what if Trayvon was your child?").

A lot of folks are asking what would have happened if Martin was white and Zimmerman was black. I think it's a good question to ask, and unfortunately the verdict could have been very different. Another question that I'd like those people to ask is "what if Zimmerman's last name was Sanchez, or Juarez, or Mesa (his mom's maiden name)?". Would there still be these claims of racism?

Comment Re: Um, they used what? (Score 1) 165

I'm a mass spec guy, so I certainly agree that different masses will focus differently. But in the ion drive schematics I see online, I don't see where there is a focussing step. The plasma is made, then just accelerated across a planar electrostatic voltage drop. No focussing needed. I'm also not seeing a x2 increase just from a slightly better ability to focus even if that did matter.

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