Timeline for Why is it assumed that the universe started out with a size equal to the Planck length?
Current License: CC BY-SA 4.0
9 events
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| Apr 21, 2023 at 8:20 | comment | added | user50623 | @PM2Ring It was interesting to read in that reference that there should be gamma rays scattering off particles at the Planck length now from cosmic sources . But I think that would only apply if the particles at the Planck length had electromagnetic properties | |
| Apr 21, 2023 at 8:16 | comment | added | user50623 | @James K I should have said a ball of quarks. It is curious though that a black hole of a few solar masses would have a quark ball with radius about the radius of a oroton and the largest black holes a radius about the maximum distance of the strong force. Also that radius for the universe as a whole is not far off some intermolecular bond distances . | |
| Apr 21, 2023 at 3:39 | comment | added | PM 2Ring | There's some relevant info at Did the Big Bang happen at a point? & physics.stackexchange.com/a/185943/123208 | |
| Apr 20, 2023 at 23:14 | comment | added | StephenG - Help Ukraine | The Planck units are not units which are fundamental in some way. They're just order of magnitude constants that are roughly at levels which mark the range where we don't have good theories. They feel natural for some purposes - a little easier to manipulate some equations using these units. | |
| Apr 20, 2023 at 19:30 | comment | added | James K | Don't try to treat protons as "balls", or the universe as a fixed spacetime in which a ball of protons exploded. | |
| Apr 20, 2023 at 19:29 | comment | added | James K | I don't think this assumed. Indeed the usual assumption is that the universe was always infinite in extent (even if this causes philosophical problems. If the universe had a start (and there wasn't an infinite period of inflation, for example, which come with their own philosophical problems) then our current understanding of matter has difficulty with times at a scale less than one planck time We don't really have a model of reality that can deal with such time intervals, so we can't currently talk about what happened in the first planck time. | |
| Apr 20, 2023 at 19:05 | review | Close votes | |||
| Apr 28, 2023 at 16:42 | |||||
| Apr 20, 2023 at 18:50 | comment | added | Mithoron | Oh, and who says that? Earliest Universe we can tell anything would be perhaps having density comparable to Planck density - that's completely different situation than you say. | |
| Apr 20, 2023 at 17:49 | history | asked | user50623 | CC BY-SA 4.0 |