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visits member for 2 years, 11 months
seen Mar 18 at 17:35

Aug
30
comment Assuming an observer is 50 light years away, in the plane of the solar system and observing earth, what is the light flux of earth he would see?
Hi Martin, would be great if you can also fill in the missing details and answer the OP's question with more concrete value.. OP already mentioned "earth-like", so how about assuming a sun-earth system. Otherwise, IMO, the answer is not complete.
Aug
26
comment What exactly is the definition of motion and its relation to Mach's conjecture?
@ Pete Jackson: could you please answer the question in my above comment?
Aug
26
accepted Relationship between the cosmic microwave background (CMB) radiation and the visible universe
Aug
24
comment How fast will the sun become a red giant?
This is also quite an interesting paper The search for a strategy for mankind to survive the solar Red Giant catastrophe.
Aug
23
comment What would a rotating black-hole look like to a “geo-stationary” observer orbiting the black hole
yes that is the question I was asking (I think).
Aug
23
comment What would a rotating black-hole look like to a “geo-stationary” observer orbiting the black hole
We can, at least in theory, have a black-hole where the angular velocity at a distance slightly outside the horizon is less than the speed of light. Or am I wrong?
Aug
23
accepted Can we model gravitation as a repulsive force?
Aug
23
comment What makes us think we can actually detect gravitational waves?
@Wedge: even if the space-time contains some very "solid" objects, such as neutron stars? another question: inside a distorted space, wouldn't a ruler also get distorted, and therefore, length itself. Consequently, nullifying the time difference you mention (for the 1st question)
Aug
22
asked What makes us think we can actually detect gravitational waves?
Aug
5
answered Can we model gravitation as a repulsive force?
Aug
5
asked Can we model gravitation as a repulsive force?
Jul
29
comment What exactly is the definition of motion and its relation to Mach's conjecture?
However if we can test the planet to be rotating, it would automatically imply an external frame of reference, which can be considered absolute. Say the radius is r and angular velocity w. That means, at any instant, a point on the equator is moving at w*r with respect to something.
Jul
29
asked What exactly is the definition of motion and its relation to Mach's conjecture?
Jul
29
comment Is the observable region of the universe within the event horizon of a super-massive black hole?
@Rory, this is an interesting question and I would not classify as trolling.
Jul
29
comment Do all black holes have a singularity?
I remember reading somewhere that for ordinary degenerate matter, the event horizon is inside the object, so it is not a black-hole or a singularity. I think some basic calculations could help here. For instance, a neutron star is several kms in radius, while the event horizon will be a few hundred meters. Also, it is believed that there are more degenerate states, for instance quark matter.
Jul
29
asked What would a rotating black-hole look like to a “geo-stationary” observer orbiting the black hole
Jul
18
comment What is so special about iron?
Its an irony that Iron is very stable, and yet, a little water can effectively make it into dust.
Jul
18
comment Relationship between the cosmic microwave background (CMB) radiation and the visible universe
great answer. So right now there is no "hard evidence" that the CMB is the signature of large scale structures in the universe?
Jul
17
asked Relationship between the cosmic microwave background (CMB) radiation and the visible universe