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An under water explosion creates a bubble which quickly collapses on itself. The action takes less that 1/100 of a second for bubbles less than a foot across. This creates a point of extremely focused energy at the middle point where the bubble collapses. In theory, this point focuses enough energy to trigger nuclear fusion.

Could the same effect be achieved by suspending a metal sphere under water which contains a near complete vacuum. If the sphere were opened uniformly along all of its surface area, the water rushing should create the same effect as the explosion, focusing all of the energy on a point at the center of the sphere.

IF not, then what are the limiting factors (surface tension maybe?) In my mind, It seems the major limiting factor is the shrinking surface area of the bubble as it collapses. as the surface area shrinks, the water molecules along the surface of the bubble would resist the change of surface area (some would need move away from the surface, in the oppisit direction of the collapse), causing the collapse rate to slow.

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    $\begingroup$ How will you (1)open the sphere uniformly, (b) suspend your target materials at the focus? $\endgroup$ – Carl Witthoft Mar 31 '14 at 16:43
  • $\begingroup$ I have no idea. This is just a hypothetical question at the moment. I'm curious to know if the concept is sound, and if not, why? $\endgroup$ – Hoytman Mar 31 '14 at 17:09
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This creates a point of extremely focused energy at the middle point where the bubble collapses. In theory, this point focuses enough energy to trigger nuclear fusion.

It is not currently accepted mainstream science to say that collapsing bubbles focus energy enough to cause nuclear fusion. Temperatures over 10,000K can be acheived, but are still well below the millions of degrees needed for fusion.

See the extensive review article Single-Bubble Sonoluminescence for detailed information.

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  • $\begingroup$ Is there a chart plotting the final temperature vs bubble size? That would be an interesting relationship to establish. $\endgroup$ – Hoytman Mar 31 '14 at 21:26
  • $\begingroup$ I'm not aware of a chart like that, but I don't think this is a case of bigger = higher temperature. I think the smaller bubbles are more spherically symmetrical. Also, think of all the torpedoes and bombs that have exploded in the ocean; they don't result in nuclear fusion. The hottest bubbles seem to be cavitation bubbles in water that has been deaerated and noble gasses dissolved. $\endgroup$ – DavePhD Apr 1 '14 at 1:27

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