Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Comment Re:My question is ... (Score 2) 33

I have no clue where you're coming from. You rightly point out that life takes energy, but then proceed to consider internal sources of energy as worthless, when in reality in the universe far more things are exposed to internal energy than external. And radioactive decay-driven energy sources are only one. For example, Encelaldus's heat seems to be driven by the serpentization of rock, which also releases hydrogen, a potential food source to microorganisms. There are numerous chemical means which can release vast amounts of energy - yes, nuclear energy is many orders of magnitude more dense, but non-radioactive elements are also orders of magnitude more common.

Anywhere that there is heat and fluids (or solids that can undergo solid-state convection) can experience that heat being turned into harvestable forms of chemical energy, because chemical equilibriums are different at different temperatures. For example, at STP conditions, N2 + O2 is favorable, while at high temperatures NO2 is more favorable. N2 + O2 that goes to higher temperatures and forms NO2, which then comes back down to the lower atmosphere, is bringing a source of chemical energy with it.

Since heat differentials can and will be readily converted to chemical energy wherever it's associated with convection of any variety, then any source of heat is a fuel for life - and heat most definitely doesn't only come from nuclear decay - or chemical reactions. It comes also from the rebalancing of layers to a lower gravitational equipotential. It comes from impacts. It comes from tidal heating. It comes from thermal cycling in elongated orbits. It comes from mass loss due to solar wind exposure. There's a vast range of potential heating sources in the universe that can create heat differentials. And heat differentials make exploitable chemical reactions.

You make blind assertions that "these environments wouldn't be likely because of their composition". What do you know about this? You have a sample size of one of chemical processes that have created life. We can't even see deep into our own world to see what other alternatives might exist at higher pressures, let alone in other worlds. Heck, underground doesn't even mean particularly high pressures. Dwarf planets can have Earth-surface pressures at hundreds of meters or even kilometers depth. And life on Earth exists fine in the deep sea, wherever there's energy to support it, where pressures are at over 1000 atmospheres

Deep environments might prove even more prone to organic chemistry. In general, pressure is usually associated with faster reaction rates. You also often have more complex arrangements of possible chemical phases for each compound at higher pressures than with lower pressures. Water for example over its possible temperature range at a particular depth might have 3-5 potential ice phases, a liquid phase, a supercritical fluid phase, and a gas phase. This leads to a much greater range of possibilities for reactions to potentially exploit, because each chemical in each of its phases has the potential it interact with each other chemical in each of its other phases, or in the case of non-metastable forms, at least many of its other phases.

Common theories for the origin of life on Earth usually assume that it wasn't the sun that powered the first forms of life, even though that's the most convenient source of energy on our planet. Photosynthesis is much more complicated than most forms of chemosynthesis. Environments like black smokers, volcanic pools or acidic waters within deep iron-rich minerals seem like far more likely candidates.

Intelligence evolving within creatures that live in liquids? Oh, we've never seen that before! ;) Except, of course, for the fact that the second-most intelligent category of mammals are aquatic (cetaceans), and the most intelligent invertebrates (mollusks) live there too. Rather, the oceans tend to be highly competitive environments, and thus good breeding grounds for intelligence.

The only reason that our deep seas seem less rich with competing life is that our deep seas are usually relatively energy devoid. Which says absolutely nothing about subsurface layers on other planets. Wherever our deep seas are not energy devoid, such as around black smokers, they tend to be flush with life.

Comment Re:My question is ... (Score 2) 33

I think it's silly in the regards that we have precisely one datapoint about the sort of environments in which life may exist, which is pretty terrible in terms of making any sort of definitive statement. I'd much rather they keep their options open, check out a wide range of environments, and just look for signs of "things that are hard to explain", whatever they may be. "Hmm, this body has both a strong oxidizer and a strong reducing agent in its atmosphere - how is that happening?"

I'm not saying "check planets in random order" or anything of that nature. Just that I don't think it's critical to obsess over being sure to examine them in order of "earthishness" from highest to lowest. We need to be looking at a diversity of worlds.

Heck, we don't even know whether the surface of a body is the best place to look, most life in the universe might be in sub-crustal layers for all we know. Certainly would partially help explain the Fermi paradox, if it were such that we rare "surface dwellers" have a far easier route to the cosmos than something that needs to be under gigapascals of pressure to survive and whose radiating transmissions, if any, would be blocked by their planet's crust.

Submission All Malibu Media subpoenas in Eastern District NY put on hold

NewYorkCountryLawyer writes: A federal Magistrate Judge in Central Islip, New York, has just placed all Malibu Media subpoenas in Brooklyn, Queens, Long Island, and Staten Island on hold indefinitely, due to "serious questions" raised by a motion to quash (PDF) filed in one of them. Judge Steven Locke's 4-page Order and Decision (PDF) cited the defendant's arguments that "(i) the common approach for identifying allegedly infringing BitTorrent users, and thus the Doe Defendant, is inconclusive; (ii) copyright actions, especially those involving the adult film industry, are susceptible to abusive litigation practices; and (iii) Malibu Media in particular has engaged in abusive litigation practices" as being among the reasons for his issuance of the stay.

Comment CDDL and GPL don't mix (Score 2) 185

Regardless of what Ubuntu has convinced themselves of, in this context the ZFS filesystem driver would be an unlicensed derivative work. If they don't want it to be so, it needs to be in user-mode instead of loaded into the kernel address space and using unexported APIs of the kernel.

A lot of people try to deceive themselves (and you) that they can do silly things, like putting an API between software under two licenses, and that such an API becomes a "computer condom" that protects you from the GPL. This rationale was never true and was overturned by the court in the appeal of Oracle v. Google.

Comment Dash Computers are Suboptimal (Score 1) 335

In 10 years, it will still be a fine car but the dash computer will be an antique. My car has bluetooth and a phone jack, and that will allow me to hook up the latest equipment to navigate and entertain me, for a long time, and replace it on my own schedule.

Comment Re:9 women can't make baby in 1 month (Score 1) 264

I've read the book a couple of years ago, and in my Software Engineering courses in college in the 90s, the same thing was said. Also 15 years in the industry and I've heard the line "If you can't make it on time, we'll add more people to the project" over and over again. Mostly by clueless Project Managers without a CS/SE background.

Comment 9 women can't make baby in 1 month (Score 1) 264

I think it's the same premise, but inverted. Management thinks the project will be finished faster if adding more man-power, but actually the inverse happens, it will be finished even later.
A logical fallacy is not taking into account the complexity of a task. If one woman makes a baby in 9 months, 9 women should be able to make a baby in 1 month.

Comment Re:The movie was good because the book was short. (Score 1) 235

If you want to keep "doing the math" and if you want to be called "hard sci fi", you need to do the math right. You can't say that because you've got 50 liters of oxygen that you're going to get 100 liters of water because O2 + 2 H2 = 2 H2O. Yet Weir does exactly that, over and over and over again, mixing up moles, liters, and kilograms. One of dozens of categories of huge fundamental science mistakes that he keeps repeating.

Comment Re:The movie was good because the book was short. (Score 1) 235

I'm sorry, I missed out where "accuracy" and "popularity" became interchangeable terms. I was responding to a post talking about the book's amazing scientific accuracy, when in reality it's a veritable MST3K of glaring science errors on almost every page. Or at least glaring to anyone who knows anything about the scientific fields involved.

At least with "soft" sci-fi where they don't try to explain how everything works you only get hit over the head with science problems whenever they describe a situation that's literally impossible. With bad pseudo-hard-sci-fi you get hit over the head with it again and again.

Comment Re:Are and storms that fierce on Mars? (Score 1) 115

First, 1KW light output is if you want Earth's equatorial sunlight, which is far more than plants need - they saturate their input at far less than that.

Yes, one has to incorporate a "capacity factor" to account for angles, night and clouds. Something like 15% would be typical for potato-growing regions. But at the same time, when light is coming from LED lighting, you have to account for stray lighting (light that's not hitting your grow area) and efficiencies at generating PAR, which are 20-30% for proper grow lights, lower for normal room lights (as the phosphor wastes part of the light energy to make it a comfortable white rather than a painful pink). The two issues roughly cancel themselves out. You need in the ballpark of 1kW per square meter of electricity input to match normal potato growing conditions.

I arrived at 500W (input) of LEDs to produce the needed output for 1m^2

For 24-7 lighting, that's 50% of my above, but let's go with it.

, and about 2.5m^2 of solar panels to power them up.

Not even close. Your solar array too has a capacity factor - in the ballpark of 15% if fixed, maybe 35% or so if tracking. Then you have your panel efficiencies. The best large scale commercial panels are 22-23% efficiency. You might get 30%-ish if you used absurdly-crazy-expensive spectrolab cells. Then factor in dust constantly settling on the panels - say 25% loss even with regular cleaning. And Mars's solar constant is only 588W/m^2 *in space*. Earth's is about 1kW/m^2 *on the surface*, 1,4kW in space.

As in the book, 500W for lights per square meter would take 67 square meters of panels per square meter of crops. The best possible situation would take 10,5 square meters of panels per square meter of crops.

Note this is using your 500W figure, which is being kind to you. Double the required panel area to reach mine.

yep, 1m^2 per spotlight, 12 per rover (per movie)

Pure nonsense. 6kW of power consumption for LED lights on a rover? Um, no. Never. Period. That's patently absurd, you'd burn through your power supply in a heartbeat. That's the sort of power you'd use to run a drive motor on a rover on Mars - if you wanted it to drive at speeding-on-the-highway speeds at that. The Lunar Rover motor was only 0,1kW.

  How the heck would you even cool a 500W LED spotlight (let alone 1kW, let alone 12 of them) in the near-vacuum atmosphere of Mars? The heat sinks would be massive. LEDs can't run hot, they have to be kept close to room temperature. I have some 600W grow lights. They have a 15kg heat sink and a half a dozen fans on each of them. And you can't practically just cool things with fans on Mars. And they're not like "spotlights", they're about half a meter by half a meter behind the glass panel, and have to be to keep the LEDs far enough apart. It's the reason why LED headlights for cars are a brand new thing, it's very hard to cram many LEDs into a small space without them overheating. A typical modern LED headlight is only about 15W; I was being generous and assuming bright 30W lights.

I wish you were here so I could show you what a 600W LED grow light looks like. It's blinding. The whole world looks pink for a while afterward. And they're massive, heavy things. To put it another way: 600W LED is equivalent to about 5000W incandescent.

I wonder how much could be saved by adapting growth density. Say, he could light up all the saplings with 2-3 lights, but as plants grow, they need more space. So instead of one massive harvest, to make it so that the grown plants take half the available light, grown in 3/4 half of the remainder, half-grown half of the remainder of that, and so on.

The optimal growth method is having 100% of your area lit up at all times, with leaves intercepting 100% of the light. Which can be approximated using a reflective grow tent, thick ground coverage, and harvesting wherever the leaf density starts getting enough that plants are shading themselves out.

But before you start thinking about all sorts of "clever" ways one could try to exchange human labour for increased yields, you have to understand how terrible an unventilated improvized grow environment with "whatever happens to be around" as your growth medium is. You don't have experience with this so can be forgiven for not understanding, but it's incredibly easy for one little screwup that nobody ever could have seen coming (except someone who's done it before you) to come in and wipe everything out in no time flat. I can't begin to tell you how many plants I've lost over the years, in waves, from how many different means. Here's one little one for you to google: ethylene gas. That one got me many years ago when I got "clever" and decided to reduce my greenhouse heating costs by better sealing all of the cracks. Inexplicable temperature spikes when I wasn't around were my bane about a year ago (that one took a *long* time to figure out, I'd just walk in and find half my plants dead - it turned out to be due to how open or closed a door to an adjacent room was). A month ago it was the hygroscopic nature of my fertilizer having soaked up enough humidity that it became too mobile and got released too fast after being added to the soil and thus burned my plants. I could lists literally dozens of these sorts of things. Indoor growth environments suck for plants. They're not evolved to it. With perfect management and unlimited access to raw materials and hardware from Earth, you can get plants to grow well, but it takes process refining, it takes encountering screwups and trying again.

Alternatively, how lethal would space radiation be to potatoes? An extra "tunnel" from transparent plastic, where mature plants would use direct sunlight.

This is actually more practical. There was an experiment scheduled to fly on the Mars 2020 Rover, the Mars Plant Experiment (MPX), to test exactly this (although not with potatoes). It didn't get selected. The jury is still out, so this is a place one could forgive artistic license.

Another option one could have written into the book would be to have a very large "hab with a view", aka, covered in windows for natural lighting. Still, the light levels there (esp. after going through multi-layer plastic) would be really painfully low for the plants. A way to compensate would be for Weir to have designed the solar power farm to be operated by heliostat reflectors. In such a case, he could steal heliostats from the farm and beam light directly into the hab. This would avoid all of the stages of loss involved in conversion of light to electricity and back to light, giving over an order of magnitude more energy imparted. With enough light beamed in laterally, one could have them up on shelves, several high, minimizing the necessary floor space.

But regardless of where the light comes from, however, there's another problem: tens of kilowatts of energy imparted into the habitat, there's no way whatsoever that whatever cooling system was designed into the habitat would be able to handle it (whether passive radiation or active). The situation is worse coming from lights, as you're also dumping the waste heat into the habitat (several times the light energy), but it's pretty terrible in either regard. But regardless, Weir could probably have hand-waved it away with stripping insulation off of the hab - it'd just have to be a very large hab to have enough surface area.

Could have, would have, should have. But as it stands, it's 2-3 orders of magnitude off. Which is head-bangingly bad to anyone who knows anything about growing plants indoors. It's like what it would be like to you (assuming you know how to program) if someone wrote a book with a programmer main character and went into detail about him "programming", and it was absolutely nothing like programming. Something like "He put on his headset and opened up the for-loop. 'Oh, here's the bug!' he said, watching it crawl past him as he drew his debugging pistol. ZAP!!! 'That'll fix this if-function! Now I just need a few more K and the variables should start to process.' " Think of how painful it'd be to read a book that went on for pages and pages like that. And then everyone talked about how much of a "hard science" book it was with "realistic depictions of programming". That's the boat I'm in whenever these threads come up :

This is the theory that Jack built. This is the flaw that lay in the theory that Jack built. This is the palpable verbal haze that hid the flaw that lay in...