Electric Sun & Nuclear Fusion I
Let me ask you a question. Is there anything that would falsify the mainstream view of Nuclear fusion in the stellar interior?
So your saying it can't be falsified? That's a worry.
In principle, of course it can be, or more correctly
could have been falsified. But today, in light of present knowledge, probably not. But you must remember that science is a "moving target". Ideas, hypotheses, theories, models & etc. don't stand still, but rather evolve with time. Nuclear fusion, as a power source in the solar/stellar interiors, has already been tested in the manner you are looking for, and has already been confirmed. There are no mainstream scientists at work today, so far as I know, to test the fundamental question, whether or not nuclear fusion is the ultimate power source for the Sun because that question has already been researched & verified. Time to move on and study the details of the process. Indeed, if that fundamental idea is wrong (an extremely unlikely event), then it will eventually become obvious; how, after all, can one observationally & consistently confirm the details of a process that does not actually exist?
Back in the mid to late 1800's, when scientists began to study the Sun seriously, the assumption was that the ultimate power source was heating by the conversion of gravitational potential energy into heat energy by gravitational contraction. This is a perfectly reasonable and viable idea. Prominent figures in this effort were
Hermann von Helmholtz &
William Thomson (Lord Kelvin). Helmholtz derived a likely age for the Sun of 22,000,000 years in the 1850's, while Thomson later derived a likely age range of 10,000,000 to 500,000,000 years. And that was as old as the Sun could be if that were the primary source of heat. But as it became obvious that Earth was much older than that, literally billions of years old, this idea of gravitational contraction as the ultimate source of energy fell out of favor. It simply could not be made consistent with the obviously much older age for the Sun.
But by the turn of the 1900's, radioactivity has been discovered and nuclear physics began to be a serious science. It was quickly realized that nuclear energy could power a much older Sun.
Ernest Rutherford suggested radioactivity (that's nuclear
fission) as the power source in 1904. But it did not take long for scientists to recognize the
mass deficit in heavier nuclei; this is the fact that the mass of a nucleus is measurably less than the sum of the masses of its constituent particles. This was understood as mass converted to binding energy, in accordance with Einstein's famous equivalence
E = Mc2. This is all reviewed in detail by Sir
Arthur Eddington in his landmark book
The Internal Constitution of the Stars (1926, 1930; see chapter XI "The Source of Stellar Energy"; book still in print through Dover publications). Eddington points out that the energy involved in this "mass deficit" is quite enough to power a Sun as long as 100,000,000,000 years, easily long enough to settle the age problem for the Sun & Earth.
This marks the foundation of the hypothesis that nuclear
fusion is the ultimate power source for the Sun. Eddington knew that the energy was enough to fit the observations, but neither he nor anyone else knew of any specific process by which that energy could be released (they knew radioactivity was not that process). Eddington did not suggest any specific process. But
Subrahmanyan Chandrasekhar took the next step in his equally landmark book
An Introduction to the Study of Stellar Structure (University of Chicago Press 1939, still in print through Dover Publications; see chapter XII "Stellar Energy"). Chandrasekhar outlined a series of plausible nuclear reactions and demonstrated that the energy release in these reactions were consistent with observed characteristics of stars.
At the same time Chandrasekhar's book came out,
Hans Bethe led the charge in the next major step. He proved specifically that the basic proton - proton (
PP)and Carbon - Nitrogen - Oxygen (
CNO) fusion reaction chains were entirely consistent with and allowed by nuclear physics and quantum mechanics and would in fact power a star (see
Bethe & Critchfield, 1938;
Bethe, 1939a;
Bethe, 1939b; and also of interest are
Bethe & Marshak, 1939 and
Bethe, 1940). These papers marked the transition of nuclear fusion as a stellar energy source from an hypothesis to a genuine theory, with a solid foundation in theoretical & experimental physics.
But of course this was followed quickly by WWII, atomic (
fission) bombs and hydrogen (
fusion) bombs and very rapid advances in both theoretical and experimental knowledge of nuclear physics, and specifically the reactions attributed as the source of stellar energy. These reactions were heavily studied in the development of fusion weapons, and that knowledge made its way into the next major study published after Eddington & Chandrasekhar, the book
Structure and Evolution of the Stars by Martin Schwarzschild (Princeton University Press, 1958; still in print through Dover Publications; see chapter 2, section 10 "Nuclear Reactions"). By now the rates & energies of the specific reactions expected in stars were known and utilized by Schwarzschild. He was the first to offer this kind of detail and the first to take advantage of the post WWII knowledge derived from weapon studies. He was also the first to expand the topic from simply stellar structure to stellar evolution, in detail.
By this time it was well established that these nuclear reactions were undeniable in terms of both theoretical & experimental physics. They were known to be physically possible & probable. The only question that remained was that, while they were known to be probable, were they known to actually happen in actual stars? This was assumed, and these processes assumed to be in fact the source of stellar energy, because there was no other physical process known which could be consistent with observed stellar properties, which remains the case to this day. But considering that a stellar core is not directly or indirectly observable by any means available at that time, how is one to observationally verify that nuclear fusion really is the ultimate power source for stars? The answer was recognized immediately:
Neutrinos.
Early research revealed neutrinos from the Sun, but detected too few of them, which implied far less nuclear fusion in the Sun than was required to match its observed energy output, a serious problem. But eventually the theory & experiment of
neutrino oscillations solved that problem, and it is now known that the actual observed flow of neutrinos from the sun is consistent with the rates and types of nuclear fusion reactions theoretically expected in the Sun. See my own webpage
Solar Fusion & Neutrinos for a detailed discussion of this part of the story, including copious references.
This determination of the solar neutrino flux provides the first direct observational confirmation that nuclear fusion is ongoing in the solar core, and that the rates & types of reactions are as predicted before the neutrino observations were made. It is important to point out that each of the nuclear reactions generates neutrinos of predictable and precise energy. The observed energy spectrum of the neutrinos will therefore tell the observer which reactions are being seen (from the energy) and what the reaction rates are (from the count of neutrinos at the given energy). These types & rates precisely match what was expected prior to the observations being made. You ask "
Is there anything that would falsify the mainstream view of Nuclear fusion in the stellar interior?". Had the neutrino flux been absent, it would have falsified the nuclear fusion theory of stellar energy. But in fact it confirmed that theory. And it confirmed it not just in general but in detail.
In addition we now have the tools of helioseismology that allow us to indirectly observe the physical state of the deep solar interior in real time. That tool reveals that astrophysical models for solar/stellar interiors, developed over decades of theoretical research, are in fact consistent with the presently observed physical state of the solar interior. Most importantly, the temperature structure of the solar interior is consistent with prior theoretical expectations. That temperature structure is what sets the rate for each given type of reaction. So, the implication of the neutrino data that the types & rates of nuclear reaction are as predicted is that the temperature structure must also be as predicted. But we see that helioseismology, which more directly probes the temperature structure, produces the same result. So both observations, helioseismology and neutrinos, are mutually supportive and both independently supportive of the fusion theory. This makes the conclusion that nuclear fusion powers the sun a very strong conclusion on both observational & theoretical grounds.
Bottom Line: You ask "
Is there anything that would falsify the mainstream view of Nuclear fusion in the stellar interior?" The answer is "Yes". That "anything" you refer to has already been done and the results are in. Nuclear fusion in the stellar core is verified. It
could have been falsified had the results of observation been different, but it was not falsified, it was verified. For further reading, I suggest the book
Nuclear Physics of Stars by Christian Iliades, Wiley-VCH, 2007. The online
Lecture Notes on Helioseismology by Christensen-Dalsgaard are a good resource for basic helioseismology.
(or am I digging a hole for myself?)
