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    30. Ask a cosmology PhD student (almost) anything!

      ~science Ask
      Hi all, I am a PhD student focusing in cosmology. I wanted to up the science content here on Tildes, and I thought that one way to do so is to have an informal little Q&A session. As such, feel...

      Hi all,

      I am a PhD student focusing in cosmology. I wanted to up the science content here on Tildes, and I thought that one way to do so is to have an informal little Q&A session. As such, feel free to use this post to ask any questions you might have about cosmology specifically, and physics in general.

      This may not be as exciting as some other science AMAs given that I am a rather early graduate student, so there may be a lot of questions I don't know the answer to. However, I'm willing to try my best and answer over the next few days, and to let you know I don't know if I don't!

      A bit about myself: I did my undergraduate degree at the University of Chicago where I studied physics and mathematics, and then I was a student researcher in a computational cosmology group at a national lab. I subsequently enrolled at UC Davis to continue studying cosmology. Ask me anything about physics, cosmology, or high performance computing!

      I also invite anyone else with expertise to chime in as well!

      23 votes

    40. I have a basic and possibly uninformed question about the event horizon of a black hole

      ~space Ask
      It is my understanding that if you are looking at an object falling into a black hole from a remote viewpoint, then the object will appear to take “forever” to complete the fall into the black...

      It is my understanding that if you are looking at an object falling into a black hole from a remote viewpoint, then the object will appear to take “forever” to complete the fall into the black hole. The object is effectively frozen in time at the black hole’s event horizon, from the remote viewer’s POV.

      Is this the correct interpretation so far? If so, let’s remember that.

      It is also my understanding that a black hole can increase in mass as it captures new objects. The mass does increase from an external viewpoint. Is this accurate?

      If I understand known science on the above points, then the paradox I see here is that while the visual information is frozen in time from the external POV, the mass of the black hole does increase from the external POV. So is this where the Holographic Principle comes in? Or is there another explanation here, or am I off-base entirely?

      Or is it just that the accretion disk gains mass and black holes never increase in mass from an external POV, after they are initially formed?

      Is this known?

      Please either attempt to answer my tortured question, or point me to material that might lead me ask a better question.

      Thanks!

      13 votes