In article ,
"Robert L. Oldershaw" writes:

Somewhat related to this, at a gravitational-lens conference in Leiden
last week there was a talk on planets as discovered by microlensing.
Take-home message was that for every star there is probably one
free-floating Jupiter-sized planet. That means a couple of hundred
billion in our galaxy, but comparing the mass of Jupiter to the mass of
the Sun, even this huge population is a negligible fraction of the dark
matter in the galaxy.

That is the current *estimate*,

EVERY observation is an estimate. There is no reason to think that this
is unduly provisional, that it will be revised upward, etc.

but "a couple of hundred billion
in our Galaxy" alone not a small number and certainly not zero (as
is the case for "WIMPs", "axions, "sterile neutrinos", etc).

Remember gravitational waves. How many decades between prediction and
observation? Absence of evidence is not evidence of absence.

The fact is that we don't know what dark matter is. As such, it makes
sense to search for ALL candidates.

As the paper which started this thread mentions, dark matter could be in
primordial black holes. However, not one single primordial black hole
has been observed.

One should have the same standards for all candidates.

It IS a small number in the sense that the total contribution to dark
matter is very small, almost negligible. There are many orders of
magnitude more neutrinos, an absolutely huge number, but their
contribution to the dark matter is also negligible.