Recent content by MuggsMcGinnis

Current flow generally spreads to fill all available paths, which is why the electrical resistance for a conductive flat surface is measured in ohms/square. The size of the square doesn't matter because as the distance the current must cross increases, the width of the area it can pass through...

"Inconceivable"? Really. You can't conceive of the possibility that some material that is well-studied in the lab might exist in interstellar or intergalactic space but not be noticed until we specifically look for it? I bet I can find some examples. How would you go about observing an...

There is no reason you can't get an event horizon without matter falling through the event horizon. Consider a massive, hollow spherically symmetrical shell of matter. Suppose that the shell initially formed as a point, but mass has been added and the shell has grown. The external...

I apologize for any confusion, but, I don't refer to any reference frame at the horizon or within the horizon; only near the horizon or far from it. The model I use is no less valid than the one Stephen Hawking used in lowering a box filled with thermal energy, via a rope, to the event horizon.

I'm not suggesting that the velocities of infalling objects would subtract, somehow, from each other. I'm suggesting that relativistic mass increase is inevitable for an infalling object. Regarding "the idea of the relativistic mass is no longer used", perhaps I should refer to "momentum" or...

The Schwarzschild metric relates radius to mass: R = M (2G/c2) Since radius and mass are directly proportional, the mass density of a Schwarzschild black hole drops with radius. Density is proportional to R-2. Interestingly, (according to the WMAP 5-year results) the mass density of a...

Using the contemporary view of what happens when things fall to black holes, the apparent velocity (with respect to the black hole) of an infalling particle approaches the speed of light. Does this not yield a Relativistic mass increase? Since the net mass of the system will be unchanged...

skeptic2: You and I are in the same place, on this. I cannot (yet) see how two logically incompatible solutions can both be correct within any logically consistent system. This requires that one problem has two correct solutions: BOTH (Yes = Falls through event horizion) AND (No = Does...

Got it! Thanks. I don't know why I was being so dense on this... it would take longer than the 5.8 days for the light-pulse round-trip. So, at what point in time will the distant observer be unable to receive a reflected return-pulse? If the reflective ball ("object") is tossed at the...

Yes. I think that your old GR professor has described the problem nicely. If an event horizon is something that anything can fall through, then it's inevitable that a singularity will form.

Chalnoth How are these things incompatible? Why can you not have an event horizon (which isn't really a "thing" so much as a geometrical definition) if you don't have a singularity? Thanks

Presuming that it's possible to have "matter that is present in the interior <of an> event horizon" sort of bypasses the whole core of any discussion of whether it's possible to fall through an event horizon.

Yes, this is the crux of my problem with this. I can't get my head around the idea that reality is different for different observers. By this I mean that, the laws of physics are different, which is what this requires. If anything can fall through an event horizon, then a single universe can...

Suppose dark matter is normal matter, in an exotic state. Superfluids have some interesting properties in common with "dark matter". Superfluids are quite restricted in how they interact with their surroundings. Because a superfluid is, quantum mechanically, a single entity, all of its...

1) It's clear that, for the external observer, the event horizon evaporates before anything falls into it. 2) For the external observer, the distance to the event horizon is always less than 5.8 light-days. The only way for the laser pulse to require more than 11.6 days, round-trip, is for...