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The apparent magnitude of the Sun is -26.73; of the moon -12.6 which means the sun is about 450,000 times brighter than the full moon. (2.512^(26.73-12.6)). The full Earth is about 50 times brighter at the moon than the full moon at the Earth. So full Earthshine would be about 1/9000 as bright as the Sun at Earth. The 750 kilowatt solar power plant on the Moon would generate about 80 watts from the full Earth, if it worked at all.
Well 80 watts is better than nothing. But not much better. Maybe we could have a mirror at the Earth-moon L1, L4 or L5 LaGrange point that would shine sunlight on the solar array? L1 would be about 58,000 kilometers from the moon, I think. L4 or L5 would be about 200,000 kilometers from the moon, but would have stable orbits, unlike L1.
Bob
"The latest solar cells are about 30% efficient."
If solar cells are so efficient, why is it that the ISS solar cells apparently work at about 4%? 100 kilowatts for 2500 square meters?
Bob
I think the ISS generates about 100 kilowatts of useable electrical energy with about 2500 square meters of PV panels. That works out to about 40 watts per square meter of PV panel or an efficiency of about 3%. Something doesn’t commute in this by almost an order of magnitude.
But, if we figured PV panels could generate 300 watts per square meter (20+% efficiency), 2500 square meters on the moon would produce 750 kilowatts when pointed directly at the sun. 750 kilowatts should be enough electricity for quite a while.
Since the sun moves in the sky, I would think it would be easier to have more (say twice, or even three times as many) PV panels pointing in different directions, rather than try to steer the thing. Such an arrangement would also supply some redundancy, rather than introducing steering solar panels as another critical function.
Five thousand or even ten thousand square meters of PV panels seems quite feasible. Covering for the lunar night would be another problem, but solvable, I would think. Could the things produce any electricity from Earthshine? Paring down operations at night, some storage and a few good imaginative ideas should solve that problem.
So I don’t think nuclear will be necessary on the moon for quite a while.
Bob
I hope you noticed the words in these articles like:
“could have, This hypothesis, suggests, Lathe believes, might be, may play, may trigger”
Another way to look at the presence of a large moon is suggested by this paragraph:
“the Moon was still much closer to us than it is now. That, plus the Earth's much more rapid rotation, led to tidal cycles every two to six hours, with tides extending several hundred kilometres inland, says Lathe. Coastal areas therefore saw dramatic cyclical changes”
How can any kind of proto-life form if everything’s flooded out every few hours? Couldn’t one make the argument that a close-in large moon would preclude biogenesis? Dramatic changes every two to six hours? Or every ten million years? Which is better for life? I think I’d go for ten million years rather than two hours.
Of course, considering this paragraph:
“Earth itself may even enter such a chaotic zone when the distance between Earth and a slowly departing moon shifts in 2 billion years from its present-day distance of about 60 Earth radii to 68 Earth radii. Given that variations in tilt angle as small as 2 degrees may trigger ice ages, the forecast for Earth when its axis shifts to an angle of nearly 60 degrees would certainly be bleak.”
Bleak? I find it hard to take these guys too seriously.
In two billion years the Sun’s luminosity will have increased by more than 20%. That works out to a black body temperature increase at Earth’s orbit of more than 50 degrees C. The oceans will have boiled away and the Earth will have been uninhabitable for creatures like us for more than a billion years.
Unless somebody does something about it. In either case, I wouldn’t worry about an ice age two billion years from now.
Don’t these guys know this? Let’s read this stuff a little more critically. It sounds like a bunch of kids playing with a computer simulation. And they know everything you read on the internet is true.
Bob
“At some size with no luck we will have to justify the next size.”
Radio telescopes and optical telescopes are not usually built with the primary purpose of finding ETs, but for many other scientific reasons. Hubble is not capable of detecting ETs nor is Gran Telescopio Canarias, but both have produced, and will continue to produce, a huge amount of very good science. Arecibo, the Deep Space Network, RATAN-600 and hundreds of other large radio telescopes were not built, and are not used primarily, for detecting or communicating with ET.
As optical and radio telescope get larger there will be returns in the absence of ET detection--scientific returns of great importance, which have driven, and will continue to drive, further development.
Bob
“The catch 22 i see in building such big equipment to see our TV signals is that to build it in the first place you must know we are here, and to know we are here you must build the equipment first.”
As I keep pointing out ET doesn’t need radio to know we are here. He needs a large telescope; perhaps, a bit larger than we are currently building and which will see first light in about eight years. We’ve been using a 600 million square kilometer antenna 24.7 to broadcast the presence of a technological civilization for millennia.
“Oxygen, ozone, nitrous oxide and methane in sufficient qualities for the temperature all could indicate the existence of life. Detecting the spectroscopic signature of chlorophyll would certainly clinch that. And those gases have been around for billions of years.
Signals from agriculture, metal working and coal burning could give ET knowledge of our technology for as much as 10,000 years.
Industrial gasses such as chloroform, gasoline, kerosene, naphthalene, benzene, DDT, methyl cloride, Freon and their by-products would give ET an interesting set of patterns to follow for about two centuries.”
Bob
Excellet post Mark. Right on.
Bob
“Our radio/TV bubble only endure about 1LY then becomes background noise.”
Do you have a source for this assertion? How is it calculated? Based on what detection techniques? Does it take into account the distant early warning radars for ballistic missiles of the United States and the Soviet Union? I doubt it.
In any case, radio is the least likely means for ET to determine that we are here. Analysis of atmospheric gasses is much easier and has a much longer life span:
Oxygen, ozone, nitrous oxide and methane in sufficient qualities for the temperature all could indicate the existence of life. Detecting the spectroscopic signature of chlorophyll would certainly clinch that. And those gases have been around for billions of years.
Signals from agriculture, metal working and coal burning could give ET knowledge of our technology for as much as 10,000 years.
Industrial gasses such as chloroform, gasoline, kerosene, naphthalene, benzene, DDT, methyl cloride, Freon and their by-products would give ET an interesting set of patterns to follow for about two centuries.
Radio comes in dead last.
Bob
“Would everyone have the same chance to get to that position?”
For answers to this and other questions visit:
http://classics.mit.edu/Plato/republic.html
Bob
The scenario you suggust is like Alice in Wonderland. "Kill the King. Marry the Queen."
Invade Russia. Exterminate the Jews and Roma.
It's not worth discussing such issues with someone who has such a totally distorted understanding of reality.
Bob
“Speak for yourself. Do you want to be a slave working in a slave labor camp run by an unaccountable unelected government?”
Well, OK, OK. But try looking at it this way. Think of a bunch of prisoners chained in a cave so that they can only look forward; fed, watered, isometrically exercised, bathed and otherwise cared for by tubes and machines. There’s a battery of lights in back of them and a walking path in-between. The lights cast shadows on the walls of the cave, which the prisoners can see.
These poor people, as the days, weeks and years go by, will talk with each other. And, since about the only thing remotely interesting will be the shadows on the walls, there’ll devote a great deal of time to those and will come to understand these patterns very well. They’ll be able to make predictions about the number and shapes the shadows will take at various times, and probably be able to tell lots of other things just by long and intense scrutiny of the shadows.
But then there are a group of people who can look around and see the people and animals forming the shadows--in three dimensions and color. Maybe they can even walk outside and observe the wider world. This second group (let’s call them “philosophers”) will have spent virtually no time at all observing the shadows and would be really bad at making predictions based on the shadows,
But don’t you think the philosophers would know what was real and true far better than the others? Would they not be better able to distinguish a fan from a club? An embrace from an assault? Would they not have a far better understanding, not only of color, but of justice? Don’t you think this group would be best educated and led by the philosophers rather than the chained ones?
To return to the real world; wouldn’t we all be much better off if we were ruled by extremely talented, wise people very intensely and specially educated to be able to see reality in all its colors and three dimensions? Philosophers who would rule with reason, not passion; isolated from self-interest; seeking only justice?
Far better than some ignoramus scrambling for a position on the school board so he could mis-appropriate funds or put in some absurd ideology about philosopher kings or gender equality. Far better than democratic rule by people who only see shadows.
We could call this new kind of Republic the Platonic system.
Bob
“Nazis didn't think about exterminating the Jews until the 41' offensive on Russia failed. I'm not pulling this out of my ass. An Israeli holocaust expert said this in an interview to Der Spiegel. So If the Americans and the British did mind their own business the germans would have invaded Russia and conquered it easily.”
Either the Israeli Holocaust expert wasn’t such an expert or was misquoted. Also, the Germans would not have found the Soviets an easy conquest in the absence of Britain. The US wasn’t significantly involved until years later.
Oh, and how does failure of an invasion translate into wasting resources killing harmless people?
As for exterminating the Jews, Roma, homosexuals and the mentally unfit:
Buchenwald began operations in 1937 gradually getting better and better at killing; Auschwitz opened in 1940. Chelmo, Janowska, Majdanek, Maly Trascianiec, Sajmište and numerous other smaller camps began killing operation in 1941. There are records that in August 1941 Himmler personally witnessed 100 Jews being shot. Work commenced on the Belzec death camp in November of 1941.
Now follow the dates carefully:
Germany invaded the Soviet Union on June 22, 1941. The Germans didn’t suffer a serious reverse until November 21, 1941 (at Rostov). They didn’t suffer a serious (but by no means fatal) defeat until late December 1941 (at Moscow). By this time Germany had irrationally declared war on the United States. Up to this point the Soviet Union had received very, very little in the way of supplies from Britain or the United States, but more than a million Jews, Roma, homosexuals and the mentally unfit had been killed by the Nazis.
Even beyond this, I don’t think the invasion of the Soviet Union could be said to have failed until at least the end of 1942 when the Battle of Stalingrad had turned. Before then thousands of extermination facilities had been established, and millions of people killed.
Some expert. Some re-writing of history, pretty much ignoring all facts.
Bob
I don’t see the consistency in your reasoning about unconditional surrender (it discourages surrender) and your advocacy of hanging leaders, which, it seems to me, would perhaps even more powerfully discourage surrender.
In any case what about Portal, Peirse, Baldwin and Harris who ran Bomber Command, commanded, organized and directed bombing of civilian targets not only in Germany, but in occupied countries as well, particularly France?
DeGaulle who’s air force escorted the British and American bombers?
George Marshall, Chief of Staff of the US Army and Hap Arnold, the man who commanded US bombing?
MacKenzie King, Canada’s Prime Minister who sent his air force and trained pilots to help the British bomb Germany, Arthur Coningham, who commanded the 2nd Tactical Air Force?
Then of course there would be the guilty Australians, New Zealanders, South Africans and others.
We’ll get to Gandi yet.
But, with comments like “Hitler never cared for UK and USA...They only became part of it once the UK declared war on Germany and USA started to supply UK” we may not get Hitler hanged.
If those British and Americans had just minded their own business, everything would have been peachy; except maybe for the Jews and gypsies.
Do you any have Israeli candidates for hanging? Sharon’s no longer available.
Bob
“If a group of people disagree with the views of the Republic, then, provided their views aren't immoral and unethical (the baseline of which should be decided by a diverse commitee and votes from everyone), then they should be allowed to secede”
Democracies have decided that an awful lot of things are immoral, unethical and just plain illegal; and they done very drastic things to enforce those feelings of the majority:
The Fugitive Slave Act, passed by a majority of the US House, Senate, signed by the President and held valid by the Supreme Court. It was a crime to aid a slave trying to escape.
In Chicago in the 1930s, an ordnance was passed unanimously by the city council making it a crime for crippled or deformed persons to appear on the public streets since such appearance might distress the public.
Prohibition of Alcohol in the US and Norway (among other democracies). In the US the Constitutional Amendment was passed by 2/3 of both Houses of Congress and ratified by ¾ of the state legislatures. Some offenders of Prohibition laws, sentenced in the 1920s, were only released by a pardon from John Kennedy in 1963 (40 years later for those arithmetically challenged). Kennedy said that it was the only thing to do; it was too late to do the right thing.
Are you sure you can really count on your committee to do the right thing?
Today many democracies find it immoral, unethical or illegal for people to do many things, and they don’t agree:
Two people of the same sex can’t marry each other, or two people of the same sex are permitted to marry
A man can marry more than one woman, or not.
Divorce isn’t allowed, or is.
Abortion isn’t allowed, or is.
Smoking marijuana isn’t allowed, or is
You can say bad things about a company or person that you know aren’t true, or not.
There are probably a million examples; some of them really important to many people.
As Churchill said, “Democracy is the worst form of government,
Except for all the rest.”
Bob
"The Allies should have also hanged their own leaders like Eisenhower,Truman and Churchill."
What about Roosevelt and Stalin?
Bob
Since the fire bombing of Tokyo killed more civilians than the atom bombs, wasn’t it an even worse war crime? Shouldn’t Roosevelt have been hanged?
But even before that, there was the bombing of Dresden in which the British were no shy participants. Shouldn’t Churchill have been hanged? Churchill could also be charged a whole of lot of earlier bombings; mostly at night when they even see what they were bombing. How can you get more indiscriminate than that?
Stalin, of course, had a plethora of things to be hanged for.
I imagine we could also get Gandi for something. Hang him too.
I think your understanding is ridiculous and disrespectful of the more than 60 million people who perished in this greatest conflict in human history.
Bob
“The British calculated that it was in their interest to keep the 13 colonies British and not French”
I don’t think the English colonists really wanted the French to take over their colonies and have rule by Louis XV. Sort of like Indiana being defended from takeover by Iran—and then not wanting to pay a small fraction of the cost of defense.
There’s more than one side to most stories, especially including this one.
Bob
The day after the Maine was sunk in Havana harbor, Assistant Secretary to the Navy Theodore Roosevelt stated that “we shall never find out definitely” the cause of the disaster. Roosevelt's words have proved particularly enduring.
In 1999, to commemorate the centennial of the sinking of the Maine, National Geographic Magazine commissioned an analysis by Advanced Marine Enterprises, which concluded that “it appears more probable than was previously concluded that a mine caused the inward bent bottom structure and the detonation of the magazines.” Some experts, including Admiral Rickover’s team and several analysts at AME, do not agree with the conclusion, and the fury over new findings even spurred a heated 90-minute debate at the 124th annual meeting of the U.S. Naval Institute.
This does not seem to be a very firm case for going to war, but of a democracy behaving hysterically and rather stupidly.
Bob
“US couldn't leave. There were two giant Communist nations right next to Japan and several other small ones near by.”
In 1945 China was not a Communist nation. Could you name two of the “several other small ones near by?”
The US did leave in 1950. Most US troops went from Japan to South Korea when North Korea invaded the South. The new Japanese government was given sovereignty over its land and people.
Amazing that five years after the end of the largest conflict in human history, the Americans could just send their soldiers away to a new conflict without a worry about insurgency.
Bob
“the Japanese surrendered because the Soviets invaded and defeated their troops not because of the nukes.”
That is most historically inaccurate. It’s ridiculous to suggest that on August 15, 1945 a Soviet invasion of Manchuria was more of a deciding factor for the Japanese than the imminent possibilities of more atom bombs and a massive home island invasion with the potential for 10 million Japanese deaths.
Japan invaded Manchuria in 1931 and continued aggressive war against China for the next 14 years.
Japan declared war on the United States and others on December 7, 1941.
After pushing the Japanese back from their conquests in the Pacific early in the war, the US was very openly and obviously preparing a massive invasion of the Japanese home islands. An invasion which could have resulted in 10 million deaths, or more, mostly Japanese. On July 11, 1945 the Allies issued a declaration demanding Japan’s unconditional surrender and stating that "the alternative for Japan is prompt and utter destruction."
Truman had let Stalin know that the U.S. had acquired the atomic bomb. Stalin probably already knew this from Soviet spying activities in the United States, and this knowledge of Japan’s pending “prompt and utter destruction” undoubtedly speeded Stalin’s entry into the war. He was also the recipient of urgent Japanese peace overtures, which he told the Americans about, but not of the urgency.
The Americans, with their code breading abilities, were aware that an internal struggle was going on in Japan, that Japanese cables insisted on the preservation of the imperial institution and contained “fight-to-the-death rather than accept unconditional surrender” rhetoric. After nearly four years of the most bitter war, they concentrated on the later and proceeded with plans to drop the bomb.
On August 6, 1945 the United States dropped an atomic bomb on Hiroshima; on August 8 the Soviets invaded Manchuria (not Japan). On August 9 the United States dropped an atomic bomb on Nagasaki. On August 15, with the US poised to invade the home islands (and, as far as the Japanese knew, poised to drop more aom bombs), Japan surrendered.
In August of 1945 Manchuria, for Japan, was very much a side show. The complete instantaneous destruction of two major cities on their home islands were the very central focus. It’s ridiculous to suggest that a Soviet invasion of Manchuria was more of a deciding factor for the Japanese than the imminent possibilities of more atom bombs and massive home island invasion.
The story of these conflicts is important enough and difficult enough that it does not need to be obscured with absurdities.
Bob
“90% of the stars in our galaxy cant support life”
I don’t think this is correct. The overwhelming majority of stars are main sequence with masses not much larger than our sun or smaller. Nearly all of these stars will have habitable zones and all will be around for as long as our sun has been, or considerably longer.
"90% of the remaining stars wont have earthlike places."
I don’t think this is correct. Planetary systems seem to be extremely common. Even if a planetary system doesn’t resemble ours, the possibility of habitable worlds exists. The moon of a gas giant is only one of many possibilities.
"90% of the remaining total that have earthlike worlds wont be in the right place for an earthlike world."
In our solar system two such worlds exist. Between planets and moons, I would think the chance of an Earthlike world in the right place is pretty good. I don’t think you have any basis for this statement.
"90% of that total wont have big moons."
I don’t think big moons are necessary—especially if some of the abodes of life are satellites of gas giants.
90% of that total wont have a perfect mix of gasses/land/water.
You don’t need a perfect mix. Earth’s atmosphere has changed from methane to oxygen and life just keep going along. The Earth could have a lot less or a lot more water and still support life.
That life arose on Earth almost as soon as the water stopped boiling suggests that biogenesis may be easy and common.
Don’t be such a pessimist.
Bob
The 1,000 would be an upper bound. One thousand or less.
Bob
“In the next couple hundred years that civilization discover an entire new way much more efficient than radio and stops using it at all. “
I think this radio disappearing thing is an irrelevancy.
We don’t know about anything better than what we know about. A tautology, I think. One can as easily say, that there isn’t any such thing; or that such a thing would be even more obvious to us than radio; or that such a thing would be super-luminal, which would make for quite a different ballgame.
One can also point out that, even though candle technology has been far exceeded by electric light bulbs, more candles are used today in North American than were used in 1800 when candles were the principle source of illumination. There’s nostalgia and backwardness which keeps old technologies going for many centuries, if not millennia.
I don’t see how speculating that radio may go away goes anywhere. How do you distinguish it from ET going away or never having been there? Which seems as though it might have a lot more causes; and, maybe, a higher probability.
I agree entirely that communication is very unlikely if there are only 10 contemporaneously existing advanced ETs in the galaxy with the closest likely to be 22,000 light years away—whether they use radio or not. The 44,000 year round trip is rather daunting even to beings who live for a few thousand years. And understanding what technology will exist in 22,000 years on a world 22,000 light years away may be just impossible.
I’d extend that to a hundred advanced ETs. Even a thousand ETs, with a closest probable distance of 2,500 light years is, I think, probably past the edge of possibility. Which is why I think any reasonable expectation of communicating with ET implies the existence of more than 1,000 contemporaneously existing advanced ETs in the galaxy.
If the probability of advanced ETs associated with any given star system were 1 in a million or higher, then there would be 400,000 advanced ETs in the galaxy, and the closest probable distance would be less than 800 light years, and probably two or more within a thousand light years. Then I think the probability of contact would be high.
But it seems pretty unlikely that this is the case.
Bob
even if it is slow, every possible star should have been colonized by now:
This is exactly what Fermi pointed out in 1950.
Bob
“all parts of the galaxy, many millions of light years away”
The Milky Way Galaxy is only about 100,000 light years in diameter. Our sun is not more distant than about 70,000 light years from almost all of the stars in our galaxy.
Whatever the time scales I think the analysis supports the statement (in the absence of super-luminal communication):
“For us to expect to receive transmissions from an advanced ET civilization, the probability of such ETs associated with any given star system must be higher than 1 in 400 million.”
That association could arise from ET originating near the subject star, or from colonizing a celestial body near the subject star.
Bob