In article , jacobnavia
writes:

I wrote:
Normal stuff, what I think you call "baryonic". Yes, I would say the
normal stuff density could be much higher than what we think.

You answered:

No, it can't. Read up on "constraints from big-bang nucleosynthesis".


Big bang theory goes in pair with this baryonic density figure.

Not sure what you mean here. BBN predicts a definite value for the
baryonic density, which implies more baryons than are accounted for, but
much less than the total density.

Since all detectors come empty it must be normal matter, and big bang
theory has a new problem...

No. Since all detectors come up empty it means that it hasn't been
detected yet or it is in a form to which the detectors are not
sensitive.

Till now, all searches have failed. So, if it isn't non-baryonic it must=

be baryonic (normal) STUFF that we do not see.

Isn't that logical?

No. If the detectors don't detect non-baryonic matter, note that they
don't detect baryonic dark matter either, although they could. Maybe
the latter is not present here, but that can apply to the former as
well. In any case, though, BBN (based on really well understood physics
and, yes, nuclear-physics data have been updated since the Manhattan
Project) completely rules out that all dark matter can be baryonic.

And, as you know, big bang theory looks shaky to me.

The universe does not care what we think.

Too many
observations point to space being quite normal 13.7 billion years ago.

Such as the CMB?

No big bang has been ever detected.

Neither has anyone "detected" the formation of the Earth, yet we are
sure that it formed.

The big bang and non-baryonic dark matter are tied. The fact that
non-baryonic dark matter seems undetectable shouldn't make us consider
that the alternative to that: normal stuff, is more reasonable?

No; see above. And even if there is something seriously wrong with the
dark-matter idea, this in no way contradicts other evidence for the big
bang (which means that the universe is expanding from an earlier state
which was much hotter and denser).

And start searching for normal stuff that we do not see around us?

Astronomers have been doing this ever since there was astronomy.

Stars become invisible. We call them "dead" and certainly it looks like
total transformation, but they go on existing of course. Most stars will=

transform themselves into invisible matter: white dwarfs, neutron stars
and even black holes...

Very difficult to detect when quiescent.

And ruled out as dark matter; see above.

The Kepler telescope stared a huge number of stars for weeks and
weeks... If a passing black hole morphs the star image into a ring, that=

could be detectable isn't it?

Has anyone done that?

[[Mod. note -- Yes. It would take very high angular resolution
to actually resolve the "Einstein ring" you refer to, but such a
"gravitational lens" also brightens the image, and this "microlensing"
can be detected. Among other interesting discoveries, this technique
has discovered a number of extrasolar planets, and placed limits on
possible populations of free-floating black holes or "Jupiters". See
https://en.wikipedia.org/wiki/Gravit...l_microlensing
For a bit more information.
-- jt]]

Microlensing shows that compact objects of the mass of stars cannot be a
substantial fraction of dark matter.