Forgot your password?

Comment: Re:Should we say hello? (Score 1) 178

by Immerman (#46783445) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

The transmission power necessary to stand out against the broad-spectrum radio noise generated by our sun would likely be truly staggering. There is some question as to whether even our most powerful military radar signals could realistically be detected from as close as Alpha Centauri. Not to mention the small but real danger in announcing our existence to a completely unknown alien species. Why not build a gravitational telescope first and peek in their windows? We could at least see what they were like 500 years ago before deciding to try to chat. And if we do decide to chat then that gravitational lens works both ways - a relatively weak signal focused by a lens billions of miles across could be heard much more easily.

Comment: Re:Air pressure? (Score 1) 178

by Immerman (#46783347) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

>Too much, it vaporizes (Venus)

No, as you increase the pressure the boiling point also increases. The reason water only exists as a vapor on Venus is not because of the air pressure of 90atm at the surface - that's equivalent to being only ~900m underwater, while the average ocean depth is about 4300m.

Instead it's because Venus is insanely hot thanks to the greenhouse effect of that thick CO2 atmosphere, which makes it far hotter than Mercury despite being much further from the sun.

Comment: Re:It's a great achievement... (Score 0) 178

by Immerman (#46783187) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

Why? We're not remotely ready to realistically send probes to another star, and unless we plan to actually land the probe on another planet, gravitational-lens telescopes would get us all the same information far faster and cheaper, while also being retargettable to other angularly-close objects of interest. And they don't much care how far away the target is, it just changes the focal distance a bit.

Comment: Re:Point and look (Score 1) 178

by Immerman (#46783097) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

True, but if there were life there then we could peek in their windows easily enough - it's only lack of sufficiently interesting targets that keeps us from building a gravitational telescopes around the sun. And if they were sufficiently technologically advanced we could potentially communicate. The lag would be horrible, but cultural and/or technological exchange could be mutually beneficial.

Comment: Re:That's nice.... (Score 0) 178

by Immerman (#46783043) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

Nah man, chuck the probe in the opposite direction. It only needs to get 0.011 light years away from the sun to act as the eyepiece of a gravitational telescope focused on the star. Maybe not quite as exciting as sending a probe to another star, but we'll be able to count the pebbles on the planet's surface within a only a few decades.

Comment: Re:People getting wierd about liquid water (Score 1) 178

by Immerman (#46782965) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

The sun will last close enough to forever for pretty much any purpose we might have. After expanding into a red giant it is expected to collapse into a white dwarf, which will survive long past the point where the expansion of the universe will have driven all other galaxies beyond the boundary of the observable universe. If we are still around and have the technology to move a few billion people between stars in anything like a timely fashion, then it will probably be even easier to simply adjust the Earth's orbit to compensate for the changing solar output. A giant ion-drive on the moon could easily tug the Earth around without significantly affecting the planet itself. For that matter we could even put a bunch of natural-spectrum lights on the near face and take the whole planet with us to a new star. Whats a few million years transit time when you're taking your whole planet with you? While we're at it maybe we could grab Mars, Venus, and all the other small planets in the system as well, and cross the cosmos as a swarm of terraformed rogue planets.

But us still being around is a pretty serious question-mark. Consider, estimates are that the sun won't begin its red-giant phase for another 5 billion years, that's about 25,000x longer than our species has existed in anything resembling it's current state, and 10x longer than it's been since the Cambrian explosion of multicellular life.

Comment: Re:They already know about Earth (Score 1) 178

by Immerman (#46782851) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

Well, if life-bearing worlds are rare enough to be interesting then if our planet was noticed there's a fair chance that aliens would have at least put a gravitational-lens telescope around their star focused on us, if only as a study in xenobiology. In which case they could quite possibly have been counting our ancestor's lice hundreds of thousands of years ago.

Comment: interstellar surveilance (Score 4, Interesting) 178

by Immerman (#46782717) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

>The sooner we launch one, the sooner our descendants get to hear back from it.

Not necessarily. Or more precisely by the time they hear back from it the information will likely be completely redundant.

At present all our mature propulsion technology is very much focused on planetary usage. Rocketry is the only one at all suitable to operating in space, and it's *horribly* inefficient in terms of specific impulse, which will be *the* deciding factor for interstellar travel. Ion drives show immense promise, already completely trouncing chemical rocketry in terms of specific impulse, but it's a technology very much in its infancy and the absolute thrust current engines can produce is miniscule, useful for little more than station-keeping and lining up gravitational slingshot maneuvers. If we launched an interstellar probe with today's technology then it's quite likely that a second probe launched 50-100 years from now would be able to make several round trips before today's probe ever got anywhere close to the target. For a mission whose expected payoff is centuries away that sort of thing is well worth considering. Much like Voyager making its pokey way out of the solar system, the value of an interstellar probe built on current-gen technology would be primarily in learning about the beginning of the path, not the destination. And unless there's some completely unexpected navigation hazard in the gulf between stars there's unlikely to be much to learn worth the cost of the probe.

Now what might be an interesting mission with current or near-term technology is a gravitational-lens telescope - rather than sending a probe towards Kepler-186f we send a telescope "eyepiece" in the opposite direction, and when it reaches a distance of only about 700AU (0.011 light years, ~10x Voyager 1's current distance) away from the sun we could start to use the sun's gravitational field as an immense lens in a telescope so powerful we could count the pebbles on 186f's hypothetical beaches. Maybe even individual grains of sand. Not to mention everything else we might see in that general direction. The downside to such a telescope is that it's extremely difficult to substantially change the target. With a telescope 700AU long even a few degrees of change requires moving your eyepiece across a distance rivaling Pluto's orbit. Still, with a clever flight plan we could get immensely detail information about dozens or hundreds of other star systems as our eyepiece slowly swept out a few degrees of motion. The only real question is, is 186f really interesting enough to be the first target? I would imagine looking toward the galactic core would offer far more interesting things to see.

Comment: Re:Better leave now (Score 4, Insightful) 178

by Immerman (#46782389) Attached to: Kepler-186f: Most 'Earth-Like' Alien World Discovered

Not at all. Einstein says nothing about FTL, accept that it's impossible to accelerate across the lightspeed barrier in normal space. There are however numerous ways in which we could conceivably "cheat" even without postulating any fundamentally new physics - from wormholes to Alcubierre warp drives. Of course if Einstein's theories are correct then any such cheating mechanism would inherently double as a time machine with rather serious implications to our concept of causality, but by this point we should all have accepted than "intuitive understanding by humans" is *not* a consideration for the laws of physics.

Comment: Re:Not so fast, Thermodynamic laws are pesky thing (Score 2) 163

by Immerman (#46775615) Attached to: 'Thermoelectrics' Could One Day Power Cars

The maximum limit on an an arbitrary heat-conversion system is that doesn't break accepted theory is the Carnot-cycle heat engine, where eff 1 - T_cold / T_hot (as measured from absolute 0). But it's a rare real-world engine that gets anywhere near the Carnot efficiency limit - a car engine might run at 1100K for an ideal efficiency of around 73%, but the reality in most cars is closer to 25%. Being solid-state a thermoelectric device could potentially operate at very near the ideal (no mechanical losses), roughly tripling the efficiency. Assuming 90% efficient electric wheel motors the total system efficiency could be nearly as high.

Comment: Re:Hotter Earth (Score 1) 163

by Immerman (#46775111) Attached to: 'Thermoelectrics' Could One Day Power Cars

Good luck with that. Human energy production is directly a miniscule factor in global warming - it's the CO2 byproducts that's the problem. In the 90+ years it takes for a unit of CO2 to be removed from the atmosphere it will capture roughly 1,000,000x as much solar thermal energy as was produced by the burning of fuel that created it. If we generated 1000x as much heat directly, but without producing the CO2, then global warming would be a non-issue.

Comment: Re:If you have to make any obligations (Score 1) 131

by Immerman (#46774953) Attached to: Code Quality: Open Source vs. Proprietary

> People have to be able to provide updates... and feel appreciated by doing so. BSD licenses allow companies to "appropriate" code,
Very true
>and then sue the original author for copyright violations...
Say what!?!?! Source code typically must be published before being appropriated, making it trivial to prove who had the prior claim.

Of course that doesn't stop a lawsuit from being *filed*, but then nothing stops me from filing a lawsuit against you for stealing my pink unicorn either.

Patent violation are of course another thing entirely - but even there the "publish early, publish often" nature of open source will very likely work very strongly in their favor if they are the original inventors.

Comment: Re:Not wiretapping: There was no wire! (Score 1) 777

Fair points. But if the recording had been made in a place where the participants had a reasonable expectation of privacy, as in not making a spectacle of themselves in a public area, then the "wiretapping" laws would likely have been applicable. As a rule "wiretapping" laws tend to be a bit of a misnomer, with actual wiretapping being only one of the specific situations where they come into play.

Comment: Re:Militia, then vs now (Score 1) 1470

by Immerman (#46774609) Attached to: Retired SCOTUS Justice Wants To 'Fix' the Second Amendment

One of the key elements of a militia versus a standing army is that a militia generally cannot be turned against the populace, because it *is* the populace. And considering that the founders had just finished fighting a blatantly illegal war for independence in which the US militia fought against the British standing army you can be certain that they were perfectly aware of this fact. A militia contains the soldiers of last resort, drawn directly from the populace, and quite possibly against the wishes of the titularly legitimate government. How exactly can such a thing happen if the populace is disarmed?

The constitution itself makes provisions for supporting a standing army as necessary, so trying to equate the militia with the army is a fool's game. The founders clearly understood the difference, and clearly wanted both to be viable.

"Text processing has made it possible to right-justify any idea, even one which cannot be justified on any other grounds." -- J. Finnegan, USC.