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Underground Experiment Confirms Fusion Powers the Sun
sciencehabit writes: Scientists have long believed that the power of the sun comes largely from the fusion of protons into helium, but now they can finally prove it (abstract). An international team of researchers using a detector buried deep below the mountains of central Italy has detected neutrinos—ghostly particles that interact only very reluctantly with matter—streaming from the heart of the sun. Other solar neutrinos have been detected before, but these particular ones come from the key proton-proton fusion reaction that is the first part of a chain of reactions that provides 99% of the sun's power.
Well, interesting read anyhow...
I thought we already knew this? It was just a theory now confirmed? Huh. I've learned my one new thing for the day, that the sun IS actually powered by fusion.
I'm with the other two posters who also thought this was considered fact.
"Computers are useless. They can only give you answers."
-- Pablo Picasso
I hope no-one finds the off switch.
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Nothing has been proven. Scientists have long had a theory about how the Sun powers itself. That theory can be used to make predictions, such as the type of neutrinos that we should expect to see emanating from the Sun. An experiment was devised to test such a prediction, the hypothesis being that this type of neutrinos is being produced and thus will be detected. Having performed the experiment, we see that the results match what we expected, validating the hypothesis. This is important and significant, and it provides further evidence suggesting the widely accepted theory is accurate, but it does not -- nor can it -- constitute a proof.
The other interesting result would be if the expected neutrino type was not detected by this experiment, invalidating the hypothesis. This would raise further questions such as: is there some other mechanism powering the Sun? Is there something deficient in our understanding of neutrinos that prevented us from detecting them despite them being there? Was there an error in the test setup (i.e. is it repeatable by other parties)?
at first I thought the underground experiment was conducted by anonymous on 4chan or something. but no, it's in fact an underground bunker lair for detecting invisible particles from the sun. that's astounding. now that the experiment is done can I lease the facility for my evil lair? why? no reason.
. . . the last professor in the once-prestigious Solar Combustion Sciences department clutches his chest, winces, and slumps face-down on his desk.
And there is the matter of neutrino oscillation, which could in itself nullify these results.
I come here for the love
using a detector buried deep below the mountains of central Italy
The linked article is in Italiano; unfortunately, my grasp of the language is limited to "ciao" and "vaffanculo."
It has been known since the 1960's that the Sun produces energy from fusion, but the actual neutrino's observed then (and until now) were high energy electron neutrinos that actually came from relatively unimportant fusion chains (from the standpoint of energy production), not the proton-proton chain though to produce most of the Sun's energy. Since there was a "neutrino problem" (the Sun appeared to produce only 1/3 of the neutrinos predicted by theory), some people did think that for whatever reason the main energy source - the proton–proton chain reaction - was for some reason mostly shut down, presumably as part of some long period oscillation in the Sun's deep interior (although Arthur C Clarke wrote a novel, "The Songs of Distant Earth," in which it was a permanent shutdown of the Sun's fusion, and a prelude to our Sun going supernova). At that time, the inability to directly see the pp chain seemed like a big deal, but since the discovery of neutrino oscillations (which nicely explain the factor of 1/3), and also with solar interior modeling from helioseismology, there has been a pretty solid consensus that the pp chain was running the Sun, even if there was no direct observation of it.
Now it has been proved. In 1990 that would have been a big deal, but now it is more a matter of just being satisfyingly complete in our observations of the Sun.
'chain of reactions that provides 99% of the sun's power'
What is the other 1% that powers the sun?
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Looks like I'm going to have to pay off a bet. I bet on hordes of gnomes on treadmills.
One of these days, I'm going to RTFA.
Making huge discoveries about the universe without leaving mom's basement? Nerdgasm!
Table-ized A.I.
the pp chain was running the Sun, even if there was no direct observation of it.
*gigglesnort*
If you are serious, you are a nut.
If you are trying to be funny, it didn't work
You appear to be unaware that magnetic reconnection was proposed specifically to address the 2nd Law problem. Name calling serves no purpose.
To be completely accurate, the sun doesn't produce any energy, it converts energy from one form (rest mass) to another form (electromagnetic radiation), increasing entropy in the process in keeping with the second law. That conversion process itself requires an input of energy (though one less than the energy output by said process) to initialize and sustain, and that energy is in turn supplied, in the form of kinetic energy, by conversion from yet another form (gravitational potential energy) spontaneously, precisely because of the second law of thermodynamics.
At one time in the history of science, it was thought that all of the energy of the sun was converted more or less directly from gravitational potential energy: a cloud of hydrogen collapses under gravity, converting its potential energy into kinetic energy, rendered macroscopically as temperature, causing the ball of collapsing gas to glow incandescently. The problem was that that process can't last for very long, so the sun (and consequently the whole solar system) would have to be pretty young, relatively (still massively old on a human scale) if that's what's making the sun glow. When we discovered that the Earth itself, and space rocks, are much older than the sun would have to be according to that theory, it required that something else be powering the sun on a longer scale. The introduction of nuclear fusion to the model solved that problem, and nowadays almost nobody even remembers that we once thought the sun was just, in effect, gravity-powered.
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Wheres the electric universe guys when you need them?
Good god man, Hans Bethe worked out the fusion processes in the Sun in the late 1930s.
http://en.wikipedia.org/wiki/B...
This may be a daft question, but if "the key proton-proton fusion reaction that is the first part of a chain of reactions that provides 99% of the sun's power." then what is the other 1% of the sun's power if not the chain of reactions?
The other interesting result would be if the expected neutrino type was not detected by this experiment, invalidating the hypothesis. This would raise further questions such as: is there some other mechanism powering the Sun? Is there something deficient in our understanding of neutrinos that prevented us from detecting them despite them being there?
That almost happened, in the early days of neutrino dectection - before things like old mines full of purified water and 3-D arrays of photodetectors running for months at a time, and you could count the number of detected neutrinos on two hands (in bi-quinary so you could go a bit higher than ten). This was when the detectors could only detect the type of neutrino directly generated by fusion reactions, and before the discovery of neutrino oscillation, when it wasn't yet clear whether neutrinos had no, or very very little, rest mass.
Early numbers, and their error bounds, made it clear that there weren't enough neutrinos being detected. (This was known for years as the "missing neutrino problem".) But the earliest ones WERE about right for a situation where all the stars EXCEPT the sun were running by fusion and the sun was out.
That may sound odd. But there was a very cute explanation that made it plausible:
The gradual gravitatonal collapse of the sun, as heat is radiated away, could power it for millenia. It's nowhere near enough to power it long enough to explain the fossil record, but it IS enough to have kept it running for historic time. Meanwhile, if a fusion reaction were to start up near the center of such a ball of collapsing gas, it would also take many years for the heat to make it to the surface. Neutrinos (which go through the sun like marbles through a light mist) are about the only signature of what's going on in there NOW.
But suppose, instead of fusing continuously, stars were reciprocating engines. They might run without fusion for centuries, or millenia, until they were compressed enough to "light up" at the center. Then the fusion heat and reaction products might make the reaction ramp up. They'd burn for a little while (which would heat them up and expand them mabye a few inches), until the decreased density and/or reduction in fuel and/or accumulation of reaction products "put the fire out" again. Repeat for the life of the star.
In this scenario, if our sun happened to be between "putts (and the very nearest stars didn't happen to have an unusual distribution of where they were in their cycles), you'd see the same neutrio flux from the rest of the sky as if all the rest of the stars were running continuous fusion. That's because it's the average of stars that are "on" and "off", and comes out to the same amount of total fusion and neutrinos.
Of course later data, both larger samples and detectors that could "see" the other neutrino types, put the kibosh on that model. A big part of it was the discovery of neutrino oscillations, allowing a stream of neutrinos that started out as one type in the sun to arrive as a mix of the three types. (This means that neutrinos have a non-zero rest mass, fly slightly slower than light, and thus experience time and are ABLE to change from one type to another.)
A pitty, thugh. By the time this was discovered I had done an outline for a five-volume fiction cycle, working through at least four genres, based on the sun going "putt" from time to time. B-b
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If you think the idea of heating via induced currents from changing magnetic fields violates the second law of thermodynamics, then maybe you should take issue with more terrestrial examples, like electric motors and eddy currents creating heat far from power plants without hot temperatures in between the plant and motor.
A lot of the people who are very pedantic on what "science" is and isn't, will always use the mathematical definition of proof. When in fact the vast majority of the world's population do not use the word in that way. In normal usage one might say "Tom stole my phone and I can prove it!", in the samme manner you could say "the sun is mostly powered by proton-proton fusion and I can prove it!"
How can such a statement possibly be wrong?
Fusion of all atoms lighter than iron will produce energy.
They were teaching school kids that the sun is powered by fusion 50 years ago. In fact, probably much longer than that. I don't recall being taught "we think the son is a fusion reactor", it was taught as fact. Finally today, we say we've confirmed it? I wonder how long before climate change can be confirmed, let alone confirming that it's man-made.
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Good god man, Hans Bethe worked out the fusion processes in the Sun in the late 1930s.
http://en.wikipedia.org/wiki/B...
Yes, but there was no direct observational evidence of it until the Homestake neutrino experiment in the 1960's. Theory is nice, but in physics the experiment's the thing. (And, when the Homestake experiment came up 66% short, there was no shortage of people claiming that Bethe was wrong in one way or another.)
You mean, this is what your new priests have been telling you your whole life? Like evolution? And that human intelligence and behavior is not genetic because it's racist?
Yes there was some direct observational evidence, the predicted nuclei being present in the sun for both the hydrogen to helium and O-C-N. You are speaking of refinement of the model and gathering of more evidence. I was just miffed by someone saying "known since the 1960s", that's in my lifetime and I know for fact my grandfather was a kid when fusion known, in 1920 Eddington had the gist of what happens in the Sun: hydrogen to helium with 0.7% of energy converted to energy.
You make good points on the limits of science. Is is possible there is no hot fusion in the sun, and duplicating such a non-existent phenomenon on Earth has been a fool's errand? See also:
http://www.thesunisiron.com/
I think it possible hydrogen may essentially outgas for statistical reasons at the surface of an iron Sun. It might also be cause by electric currents? http://www.electricuniverse.in...
Then the hydrogen fuses at the surface of the Sun's iron-nickel core. The same process may be happening at a lesser scale deep within the Earth (which has an iron-nickel core), both to cause the Earth's heat by LENR and also to produce upwelling hydrocabons from outgassed hydrogen from all the nickel-iron.
In general, the universe may be mostly iron. The history of the universe may be more about iron decaying into hydrogen (for whatever reasons), rather than hydrogen fusing into (eventually) iron.
The Earth from space looks like it is made of mostly air and water. You can't judge a large object by just what covers it. The sun's surface may be hydrogen, but we don't really know for sure what is inside -- it is all indirect guessing. What we know is that the Earth has an iron-nickel core. So why not the sun?
Science is full of data that gets reinterpreted decades later. It was well accepted the Sun was made of Iron until re-interpretation of data in the Early 1900s. Maybe it is time for another bug re-interpretation? Perhaps inspired by the recent scientific reports related to cold fusion / LENR?
http://lenr-canr.org/
Of course, I am at a loss how to disprove my hypothesis... Perhaps people here might suggest ways to do that.
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.