Yeong E. Kim at Purdue and colleagues have proposed that, in cold-fusion experiments, the deuterons condense into a Bose-Einstein Condensate (BEC). In this state, he says, they can fuse, and then the energy is collectively absorbed by the BEC. (If you’re not familiar with BEC’s, here is a very simple introduction for non-physicists, and I’ll explain more as we go.) According to him, this theory meets all the theoretical challenges of explaining cold fusion.
To learn about the theory, the best place to start is Kim’s publications page, which lists all his papers on the topic, with links to the full text. There is also a newenergytimes portal page, but it is not terribly useful.
In the opposition-to-BEC-theory camp, my google search did not turn up too many resources. I found this one-paragraph argument against the theory by Ron Maimon, and this wikiversity message board discussion (especially the first paragraph) [EDIT – link is broken, but it’s available here, thanks!], and this rationalwiki message board (there are a few insightful criticisms scattered around this long page). The criticisms echo each other, and I agree with them too. Really, all I’m planning to do is explain these arguments in more detail, so that a broader audience can follow along.
The arguments against Kim’s theory fit into two categories:
- At room temperature, the deuterons cannot condense into a BEC.
- Even if the deuterons did condense into a BEC, they would not undergo nuclear fusion, for the same reason as usual: Because the Coulomb barrier prevents them from getting close enough.
If these are true—and I believe they are, as I’ll explain in future blog posts—then the theory really seems to have no value whatsoever!
Oh, and if that’s not enough, I might suggest a third category of arguments against the theory:
- Even if the deuterons did fuse while in a BEC, it would not be magical and special, it would just be a normal 2-body fusion process, creating neutrons, tritium etc. in quantities which would be easily detected in experiments because everyone in the room would die of radiation poisoning.
Hopefully I’ll get a chance to make this argument as well.
Obviously, in his dozens of papers, Kim presents specific arguments against #1, #2, and #3. I hope to explain those arguments and why they are not convincing. This is a time-consuming task because the arguments can be pretty nonsensical! It will probably take me a few blog posts. But the good news is, we will get to learn some cool physics on the way!! 😀
Is there a plausible theory of cold fusion / LENR? 
“this wikiversity message board discussion (especially the first paragraph)” links to a page that was deleted by a Wikiversity bureaucrat, a huge mess, long story. With some substantial work, I rescued all that content, so here it is: http://coldfusioncommunity.net/w/index.php/Wikiversity/Cold_fusion/Theory/Kim
That was not a “message board.” It was actually an educational resource, and the comment you quote was out-of-place, but I never moved it. The discussion on so-called RationalWiki was on the cold fusion article talk page, and talk pages there are typically quite a mess. Snark is the Rule. (I was a sysop there until this year.)
there is a series of common knee-jerk objections to the possibility of condensates. You give one valid objection to BEC fusion for d-d fusion, but we will be discussing the others. Kim’s ideas are fairly vague, Takahashi is far more specific, and does an extensive analysis with QFT, if I’m correct. I am not qualified to assess his math. You might be.
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Dear Abd, Thank you for clarifying, and for exhuming that deleted page!
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My understanding is that forming a BEC requires that the deuterium must be at extreme cryogenic temperatures, which defeats any practical uses for it. If heat is released from a fusion event, then two things will happen: Since the ambient temperature is far higher than that of the condensate, heat will not flow to the environment. Unless there is some way to harvest that energy without heat – which I doubt – no heat will flow because of the 2nd law of thermo; entropy forbids heat transfer from a colder to a warmer system. Any heat produced will therefore remain in the BEC. That will increase its temperature, and that will destroy the BEC. End of fusion.
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Thanks for your comment! The question of whether or not a BEC will form is discussed in a different post — https://coldfusionblog.net/2014/09/21/can-deuterons-in-palladium-condense-into-a-bec/ . I think your claim “forming a BEC requires that the deuterium must be at extreme cryogenic temperatures” is quite possibly true, but I haven’t seen a detailed argument for it. Do you have one?
As discussed in that other post, it is NOT a universal law of nature that all BECs must be cryogenic; there is at least one example of a system that can form a BEC at room temperature, namely polariton lasers.
To be clear, I would be *extremely* surprised if the deuterium formed a BEC under the room-temperature conditions in question. But that’s just a guess.
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