This method has a difficulty. Most of the starlight from a galaxy comes from stars that will soon be gone. These are the luminous giant stars. But a big investment in a Dyson sphere would probably be made around a star more like our Sun which will stick around for a while. But even if most of the mass in stars is involved in this, it still won't get most of the light so long as it is the low luminosity stars that get the tech investment.
It comes down to fig. 3 in their paper. http://arxiv.org/pdf/1408.1134... Natural source don't have the expected colors for waste heat from a solid surface. But that is the case when perhaps half the starlight in a galaxy is being used for power (their gamma=0.5). So, the civilization has to be pretty much like locusts for it the be easy to discern. There may be some civilization lifetime issues to worry about in that case.
"according to a 2011 study conducted at Lawrence Berkeley National Laboratory and the University of California Berkeley, the currently estimated reserve base of lithium should not be a limiting factor for large-scale battery production for electric vehicles" http://en.wikipedia.org/wiki/L...
Actually, you are trying to sell a pig in a poke I guess. One of the links I gave points out that there is an opportunity cost for choosing the most expensive option, nuclear. We cut emissions more slowly because it cost more to do so. If you care about carbon, cut nuclear.
Let's recap. You say wind and gas will do the trick. I say good. You make a mistake on the cost of solar. I correct you. I point out that wind and gas are edging out existing nuclear on cost and you claim that wind and gas are not solar? They aren't but you seem very confused.
The question is more why are Population I stars mostly in the disk. The answer is that the disk formed later. The main sequence lifetime of massive stars is about a million years so there is not big timing issue related to that. http://en.wikipedia.org/wiki/M...
The instability that causes the collapse of a stellar core and subsequent explosion comes from turning gamma rays into pairs of electrons and positrons. This turns energy into matter and cuts the pressure that the energy provides. http://en.wikipedia.org/wiki/P... It turns out that these explosions may make observing the early universe easier. One of the most important abundance ratios is the interstellar medium is the ratio of oxygen to carbon. The strength of the carbon monoxide bond is so strong that these two really pair up. Whichever runs out first determines the remaining chemistry to a large degree. Mass losing carbon rich stars produce carbon rich dust, while mass losing oxygen rich stars produce silicate dust for example. But, primordial Pair Instability Super Novae may produce lots of oxygen with little carbon or silicon to combine with. So the very early solid phase of the ISM may be mostly water ice. This happens to increase the far infrared emissivity of this solid phase making early objects brighter in the red-shifted sub-millimeter. Thus very early object may be easy to find in surveys at that wavelength. http://iopscience.iop.org/0004...
The universe cools as it expands. Once the background radiation is cool enough then the heat of contraction can dissipate. Initially, growth of structure in the universe happens only in dark matter because the normal matter smooths out destiny fluctuations. But after recombination, the normal matter begins to catch up. http://books.google.com/books?...
You've got this right. Rotational transitions are the important ones (aside from atomic carbon). For molecular hydrogen, these are at higher energy so the most abundant molecule does not contribute much to radiative cooling normally. It does become important in primordial gas, but then the gas has to be warmer to excite those transitions.
Slashdot Mirror
I was thinking them. Other galaxies are pretty far away.
They can be assimilated?
This is not a search for plants but rather Dyson Spheres. http://en.wikipedia.org/wiki/D...
Would we want to? They sound like locusts.
This method has a difficulty. Most of the starlight from a galaxy comes from stars that will soon be gone. These are the luminous giant stars. But a big investment in a Dyson sphere would probably be made around a star more like our Sun which will stick around for a while. But even if most of the mass in stars is involved in this, it still won't get most of the light so long as it is the low luminosity stars that get the tech investment.
It comes down to fig. 3 in their paper. http://arxiv.org/pdf/1408.1134... Natural source don't have the expected colors for waste heat from a solid surface. But that is the case when perhaps half the starlight in a galaxy is being used for power (their gamma=0.5). So, the civilization has to be pretty much like locusts for it the be easy to discern. There may be some civilization lifetime issues to worry about in that case.
These are infrared array cameras mounted of space telescopes. How high tech do you want? http://wise.ssl.berkeley.edu/
"according to a 2011 study conducted at Lawrence Berkeley National Laboratory and the University of California Berkeley, the currently estimated reserve base of lithium should not be a limiting factor for large-scale battery production for electric vehicles" http://en.wikipedia.org/wiki/L...
South Carolina BBQ sauce is good. https://www.google.com/search?...
skateboard slang....
I think you might enjoy this paradox: http://en.wikipedia.org/wiki/O...
Actually, you are trying to sell a pig in a poke I guess. One of the links I gave points out that there is an opportunity cost for choosing the most expensive option, nuclear. We cut emissions more slowly because it cost more to do so. If you care about carbon, cut nuclear.
Let's recap. You say wind and gas will do the trick. I say good. You make a mistake on the cost of solar. I correct you. I point out that wind and gas are edging out existing nuclear on cost and you claim that wind and gas are not solar? They aren't but you seem very confused.
At low metalicity there is a range of stellar mass where the star is completely disrupted. Look at slide 36 here: http://www.mpa-garching.mpg.de...
I'm afraid the fact that nuclear is too expensive is just too difficult for you to understand. http://will.illinois.edu/nfs/R...
Unite! There, now this won't be seen for sure.
Hard to beat this price with a new nuclear plant. http://www.greentechmedia.com/... Can't beat it with old nuclear http://www.nukefree.org/news/V... Your information appears to out of date.
The question is more why are Population I stars mostly in the disk. The answer is that the disk formed later. The main sequence lifetime of massive stars is about a million years so there is not big timing issue related to that. http://en.wikipedia.org/wiki/M...
No, that was happening much earlier. Antimatter in the form of positrons is important in the pair instability though.
Both the high expense and the danger are known from experience.
So, we don't actually need nuclear. Good it is too expensive and too dangerous in any case.
This may help: http://articles.adsabs.harvard...
The instability that causes the collapse of a stellar core and subsequent explosion comes from turning gamma rays into pairs of electrons and positrons. This turns energy into matter and cuts the pressure that the energy provides. http://en.wikipedia.org/wiki/P... It turns out that these explosions may make observing the early universe easier. One of the most important abundance ratios is the interstellar medium is the ratio of oxygen to carbon. The strength of the carbon monoxide bond is so strong that these two really pair up. Whichever runs out first determines the remaining chemistry to a large degree. Mass losing carbon rich stars produce carbon rich dust, while mass losing oxygen rich stars produce silicate dust for example. But, primordial Pair Instability Super Novae may produce lots of oxygen with little carbon or silicon to combine with. So the very early solid phase of the ISM may be mostly water ice. This happens to increase the far infrared emissivity of this solid phase making early objects brighter in the red-shifted sub-millimeter. Thus very early object may be easy to find in surveys at that wavelength. http://iopscience.iop.org/0004...
The universe cools as it expands. Once the background radiation is cool enough then the heat of contraction can dissipate. Initially, growth of structure in the universe happens only in dark matter because the normal matter smooths out destiny fluctuations. But after recombination, the normal matter begins to catch up. http://books.google.com/books?...
You've got this right. Rotational transitions are the important ones (aside from atomic carbon). For molecular hydrogen, these are at higher energy so the most abundant molecule does not contribute much to radiative cooling normally. It does become important in primordial gas, but then the gas has to be warmer to excite those transitions.