Are there enough neutrinos & other invisible particles in a cubic light year of space to significantly affect the expansion of the universe,& at a very rough estimate without taking into account WIMPS & other exotic particles for which there is no firm evidence,what would be the total mass of this quantity of matter? Only a tiny proportion of all the neutrinos emitted since the Big Bang have been absorbed,the rest are still flying around in search of a home.

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    $\begingroup$ NB there is firm evidence for dark matter; it's just that we can't work out what it consists of. $\endgroup$ May 31, 2019 at 0:37
  • $\begingroup$ I agree with you that there is good evidence for invisible mass;the question is what comprises it,what is it made of? There is no good evidence for WIMPs,though perhaps one day there might be. Meanwhile,I think we need to know how much matter there is in the form of knowjn particles whose existence is not in doubt. $\endgroup$ May 31, 2019 at 6:41
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    $\begingroup$ If you're asking "what might dark matter consist of?" then I suggest you adjust the wording of your question accordingly. $\endgroup$ May 31, 2019 at 13:18
  • $\begingroup$ No,that wasn't what I was asking. $\endgroup$ May 31, 2019 at 13:32

1 Answer 1


Yes, there is enough of these things, especially dark matter which is accelerating the expansion of the universe.

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    $\begingroup$ in regards to accelerating the expansion of the universe, I think you mean "dark energy" rather than dark matter. $\endgroup$
    – uhoh
    May 31, 2019 at 11:55
  • $\begingroup$ The more mass there is,the more gravity should slow the expansion. It is said that dark energy is speeding up the expansion,but I can't understand where this energy is coming from. Matter & energy can neither be created nor destroyed. $\endgroup$ May 31, 2019 at 12:18
  • $\begingroup$ @MichaelWalsby Thing don't accelerate in their frame of reference, the geometry of the spacetime is changing on a way what makes them accelerating for us. $\endgroup$
    – peterh
    May 31, 2019 at 12:34
  • $\begingroup$ If dark energy is not energy but a change in the geometry of spacetime,why call it energy? $\endgroup$ May 31, 2019 at 12:42
  • $\begingroup$ No,that wasn't what I was asking. $\endgroup$ May 31, 2019 at 13:29

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