"Joseph Lazio"
schreef in bericht ...
For the record, dark matter is not a theory. Dark matter is a
hypothesis to account for various discrepancies between theory and
observation.
If one assumes that general relativity is the correct theory to
describe gravity[1], then various observations indicate that there is
far more matter around than we detect via emission of photons. So one
has two options:
1. There is dark matter, matter that is either too faint for us to
detect or in some cases that is hypothesized not to emit photons at
all.
2. General relativity is not an accurate description of gravity.
Most mainstream astronomers and physicists pick #1, for a couple of
reasons. First, GR has passed all of the other experimental tests
thrown and it, and, second, we know examples of things that are
difficult to detect at large distances (e.g., planets) or that do not
emit photons at all (e.g., neutrinos). Some physicists have rejected
#1 and tried to come up with alternate theories for gravity (e.g.,
Modified Newtonian Dynamics, MOND).
[1] On the spatial scales of interest to dark matter, the fact that GR
and quantum mechanics appear difficult to reconcile is not important.
I have great problems in understanding that you can use
the concept of dark matter in order to decide if General Relativity
is right or wrong versus if Newton's Law is right or wrong.
I have no objections if you would have used the advancement
of Mercury's perihelion in order to decide that General Relativity
is a better description of the reality than Newton's law.
The same problem I have also if you can use
the concept of dark matter in order to decide if General Relativity
is right or wrong versus if MOND is right or wrong.
I have three question related to MOND.
1. Does MOND correctly simulate the
advancement of Mercury's perihelion ?
If have a certain doubt because the N in MOND stands for Newton.
2. If I'am correct are there two flavours of MOND:
(standard) MOND and relativity MOND ?
3. Does relativity MOND correctly simulate the advancement
of Mercury's perihelion ?
Are you aware that you can simulate the advancement of
Mercury's perihelion by using Newton's Law and by introducing
a ring of (invisible) darkmatter around the Sun?
I'am not saying that physical that that is allowed
but mathematical it works.
Nicolaas Vroom.
http://users.pandora.be/nicvroom/