Black Holes & Cosmology

To answer the second part of this question first: black holes do not suck everything in. Some objects can actually orbit black holes just like the earth orbits the sun: safely. This is possible because black holes have their own gravity just like our sun does, or like stars do in general. In fact, stars …

This is an example of a question that has been influenced by science fiction literature and movies that seem to warp the truth on things like this for entertainment. But also, the science itself can be confusing. This answer will debunk the incorrect beliefs that we hold and also explain why they are wrong.So, do …

To start with, your mass is not affected at all by the speed that you travel at. People tend to believe that objects gain mass as they travel at higher speeds, mainly because old textbooks and teachings have us believe that.  But according to Einstein’s theory of Special Relativity, this is simply not true.So why …

The way dark energy is normally measured is by mapping a large number of galaxies at specific redshifts. At this point, cosmologists have models that point to a specific redshift range where dark-energy started dominating the structure of the universe, so the goal of HETDEX and other dark-energy experiments is to map a large number of galaxies around …

What is the “hierarchy” of structures in the Universe? it seems that we have moon, then planet, then planetary system, then Galaxy, then maybe “several missing” in the hierarchy?, then universe. How many “several missing” structures would there be? And would all of them just be considered clusters within clusters? Or is the “galaxy” structure …

Are astronomers convinced that dark matter is the answer? Is it likely that there is a simpler alternative theory to help explain why general relativity fails at galactic scales? I will answer the second question first: no. All the simpler alternatives have been tested and they fail to explain all the observations. It is very …

In the November/December 2015 edition of StarDate Magazine, I quote Merlin as follows, “Astronomers see the earliest galaxies as they looked about 13 billion years ago. Since the time when those galaxies emitted the light that astronomers now detect, though, space itself has expanded, so the galaxies are now 48 billion light-years away.” If those …

Can light travel without a carrier such as a gravitation field? Light does travel via a carrier, in the same way gravity does. If we think about light as a continuous phenomenon, this carrier is the electromagnetic field, just as gravity is “carried” by a gravitational field. If we think about light as a particle, then …

Based on the 2001 WMAP results, the Universe is flat with a 0.4% margin of error. But what exactly are the chances of the Universe being finite but unbounded? I know it’s an unanswered question in cosmology, but is there any estimate? The short answer to this question is that the Universe cannot be both flat and …

In the November issue of Scientific American, there is an article on the Dark Energy Survey, “Seeing in the Dark.” How is this survey similar to – or different – from HET-DEX (besides being in Chile instead of Ft Davis)? As the Scientific American article states, the five-year Dark Energy Survey (DES) will cover 5000 square degrees …

If a clock could survive in a black hole, would time stand still inside the black hole? What would space-time be like? The answer is kind of boring since we do not have physics to describe the inside of black holes, the official answer is “we don’t know”. We can speculate given what happens right …

Does the speed of light increase as it nears the event horizon due to the influence of a black hole’s gravitational pull? The short answer is no, the speed of light is always the same. To explore the subtle aspects of this question, we will consider it in the context of Albert Einstein’s general theory of …

Does the degenerate matter inside a black hole have a temperature, or is it so compact it’s functionally at absolute zero? Also, if event horizon scales with mass, does matter inside the event horizon have a specifiable density? Thanks for a very intriguing question. The basic answer is that no one knows and that it …