I was wondering this: would it be possible to "construct" elements by arranging their constituent particles in high-energy environments? So apart from just fusion, could you sub-atomically manufacture elements?

  • $\begingroup$ So, you're roughly asking "How many ways are there, by which one can make elements?" IMO, it's somewhat too broad. And your phrase "assuming technology existed" if technology existed, we can do anything. Please try to make your question more clear :/ $\endgroup$ – Waffle's Crazy Peanut Jul 3 '13 at 14:24
  • $\begingroup$ Ok @CrazyBuddy improvements shall follow momentarily. $\endgroup$ – Jason Jul 3 '13 at 14:26
  • $\begingroup$ @CrazyBuddy better? $\endgroup$ – Jason Jul 3 '13 at 14:30
  • $\begingroup$ Ahh... That was a nice revision. IMO, the question is better. As a comment, "arranging their constituent particles in high-energy environments" - like what? Sun? - Isn't that just fusion? Anyways, I'll leave it to a physicist :P $\endgroup$ – Waffle's Crazy Peanut Jul 3 '13 at 14:34
  • $\begingroup$ @CrazyBuddy I don't know, but I'm sure someone will put me out of my misery in a whirlwind of knowledge and condescension. $\endgroup$ – Jason Jul 3 '13 at 14:37

The bulk of physics obeys the time reversal symmetry. In QM that means that a process which is allowed in one direction is allowed in the other direction and that the total probability for it is the same in both directions (assuming you can set up the time-reversed final state as an initial state).

So a way to understand the delicacy of trying to assemble a non-trivial nucleus from individual nucleons is to look for the occurrence of non-trivial nuclei (or their excited states) coming apart into individual nucleons.

Alas, as far as I know this simply doesn't happen.

Which implies that doing it by intent is not merely beyond current technology, but that it is hard to envision what improvements might lead to a way to start thinking about how to finesse it. The time, space and energy scales involved are all extremely demanding.

It may help you to understand that even in light nuclei like carbon the protons have momenta up to the neighborhood of 100 MeV (which is to say they are mildly relativistic), but are confined to a volume a few femtometers in diameter. If you were to shoot a free proton through that volume with that kind of momentum, it would pass through on a time scale on the order of
$$ t \approx \frac{10^{-14}\ \mathrm{m}}{10^{7}\ \frac{\mathrm{m}}{\mathrm{s}}} = 10^{-21}\ \mathrm{s}.$$ That's a even shorter time scale than the attosecond physics guys use!

  • $\begingroup$ Yotta is 1000 times shorter. There is a huge amount of things happens every yottasecond. What is the point? $\endgroup$ – Val Jul 3 '13 at 15:14
  • $\begingroup$ This is all true, but you could consider neutron bombardment, when coupled with the different decays, as a was to "construct" elements by adding subatomic particles. That said, it's true that a few stable elements just ruin the whole system for constructing the super-heavy elements. Those selfish bast...ions of life-sustaining greatness. $\endgroup$ – Jim Jul 3 '13 at 15:18
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    $\begingroup$ @Jim Yeah, we can do something roughly akin to s-process, but I read the OP's requests in terms of "collect the pieces then put them where we want them", which is the kind of obvious idea that is much harder than it sounds. $\endgroup$ – dmckee --- ex-moderator kitten Jul 3 '13 at 15:38
  • $\begingroup$ @dmckee the difficulty of "collecting the pieces then put them where we want them" is the reason I'm asking. $\endgroup$ – Jason Jul 4 '13 at 8:45

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