The two main differences between hydrogen and helium are that helium has a much higher mass, and would therefore have much more momentum coming out of the Big Bang, and secondly that helium is a noble gas and so it interacts very poorly with other atoms. Both of these differences would seem to have the effect of making helium far less efficient at colliding and converting its kinetic energy into thermal energy and radiating that heat away in order to undergo gravitational collapse. If helium has two attributes that make it worse at thermalisation and gravitational collapse, you would expect the hydrogen to quickly fall down to form galaxies while the helium stays in orbit outside.
Once the CMB temperature falls to below around 6 or 7K the energy of CMB photons would be too low to excite the lowest energy level of the helium, so I would expect the helium would become transparent to the CMB and be essentially looking out at a universe of zero kelvin and its temperature could fall practically uninhibited at which point you might think it could condense and form superfluid helium droplets which would be invisible to us. I would guess the size and distribution of the Bose-Einstein condensate droplets would depend on the evolutionary history of the galaxy, but you might imagine it could produce the required mass sizes.
So, are there some observations which would rule out helium as a component?
Hi,
I am sorry, I do not know that answer to your question but why is it that Helium should be 4-5 times the amount of Hydrogen?
Because of its greater mass helium will contribute more to gravitational collapse than hydrogen. At the time of the Big Bang both hydrogen and helium emerge fully ionized so chemical properties, i.e., helium as a noble/inert gas, are irrelevant. Once temperature drops we can form hydrogen H and helium He atoms together with molecular hydrogen H2. Supposedly there will be a smattering of lithium Li produced as well. The chemical inertness of helium remains irrelevant because there aren't yet any chemical elements with which He could react even it could. We have to await supernova explosions to produce the catalog of chemical elements that we have today. Helium, I should think, would have been a very active participant in forming massive gas clouds that, in principle, would collapse gravitationally to produce the earliest stars. I presume that so-called dark matter also will be somewhere, somehow in this mix. My understanding is that the photon field becomes seperated thermodynamically from the matter field to produce the relict CMB of now red-shifted photons.
Helium is baryonic matter and we know that dark matter is something different, so I don't think that Helium can be a component of CDM.
Helium makes up about 10% of baryonic matter today by number, or about 25% by mass. So it would be inadequate to account for all the dark matter. But the only reason we know CDM is not baryonic is all baryonic forms that have been suggested, just isn't there. Ergo, one cannot eliminate so-far unsuggested forms based on that argument. One still would have to look.
No, Helium is baryonic matter and we know that dark matter is something different, so I don't think that Helium can be a component of CDM. Dark Matter is no more than a false consequences to the false flat spacetime paradigm. Locally the spacetime is flat, for large structure the spacetime is no longer flat. In fact it is Hyperbolic where Virial Theorem does no longer hold.. We derive the equation of motion in the hyperbolic spacetime from GR, which traces the flat rotation curve without needs for any new mysterios Dark Matter.
Article The Big Bang hyperbolic universe neither needs inflation nor...
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