[AR] stellar fusion (was Re: Freeman Dyson, RIP)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 11 Mar 2020 14:26:25 -0400 (EDT)
On Tue, 10 Mar 2020, roxanna Mason wrote:
Also it was said that because of this million year path
that, theoretically, if the sun turned off the only way to tell is from
the neutrino flux, as if we measure them routinely in the millions.
Back when the first neutrino observatories weren't seeing anywhere near
the number of solar neutrinos expected, the error bars were wide enough
that it wasn't clear they were actually seeing *any*. So there was
serious discussion of the possibility that the Sun had temporarily stopped
fusion for some reason -- perhaps it did so at regular intervals -- with
the long lag in the heat flow maintaining its energy output.
There were a number of other theories, one of which -- that neutrinos
oscillate between different states, so any observatory that can see only
one kind of neutrino will pick up only a fraction of them -- is now known
to be correct. And the error bars have shrunk enough that we now do
definitely see some, about the number expected after allowing for the
oscillations.
Henry
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