1,812 reputation
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bio website skepsi.me
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age 22
visits member for 3 years, 5 months
seen 11 hours ago

May
28
comment Why is absolute zero considered to be asymptotical? Wouldn't regions such as massive gaps between galaxy clusters have temperatures of absolute zero?
You mentioned that "the only way we can get heat out is to place our system in contact with something cooler" - but what about techniques that don't use thermal conduction, e.g. laser cooling?
Dec
5
comment Why can we see the cosmic microwave background (CMB)?
@Alfe: There are many things that we don't know for certain, however the universe's size does not correspond directly to its age for various reasons (for example, inflation). In addition, the universe does not have a "center" from which the CMBR began propagating - it began propagating from roughly every point in the universe as the temperatures cooled. So we will never "see the last of" the CMBR, we will merely see it cool and become more sparse.
Feb
17
comment When will the Moon reach escape velocity?
@DanNeely: Oops. Obviously I hadn't read it in enough detail either. I jumped to the halfway point of the article and didn't read carefully enough. Ignore that.
Feb
17
comment When will the Moon reach escape velocity?
@DanNeely: Yes, precisely. What matters more is the concept, rather than the timescales involved, because the timescales are much longer than anything practical anyway (even in an astronomical sense). See this this article that describes the calculations behind it.
Dec
18
comment Why do electrons occupy the space around nuclei, and not collide with them?
Very interesting. On somewhat of a side note, since you mentioned the lowest orbital, what about the higher orbitals? The lowest orbital works to balance out the Coulomb force, but what causes the existence of the other orbitals? I am aware of the Pauli exclusion principle, but I don't have any intuition as to how it works.
Aug
1
comment What objects/states of objects with absolute magnitude do we know of?
Along with those are the RR Lyrae variables
Jul
20
comment Is there a method to estimate the atomic yield of a supernova of a given size?
Thank you for your answer, but what were my simplifying assumptions?
Jun
20
comment Recommend good book(s) about the “scientific method” as it relates to astronomy/astrophysics?
Annual Review - very nice, I did not know about this.
Jun
16
comment What happen when two galaxies collide?
@Cameron: Don't worry about it. I'm not an astronomer either, I'm just going off of what I know so far. We're all here to learn and to teach; that's what these sites were designed for.
Jun
14
comment Is a rogue 'exoplanet' classed as a exoplanet?
I don't think it's classed as either a planet or an exoplanet. It's classed as a rogue planet. Rogue isn't necessarily just an adjective here - it's part of the designation. Sure, it may not be technically accurate, but, then again, things like planetary nebulae have nothing to do with planets, yet the name remains as it is.
Jun
14
comment Can a moon have another large body as a satellite, and are there any examples of such?
+1 for mentioning the Death Star. :]
Jun
14
comment What happen when two galaxies collide?
@Cameron: The funny thing is that, as you said, although the stars themselves don't interact much (except gravitationally) during the collision, the gas and dust do interact, and sometimes form such "starburst" regions, like the Antennae Galaxy which you referenced.
Jun
14
comment Could the earth have another moon?
Thanks for the info. However, the ISS is usually between 350 and 400 km above the Earth's surface, yet it still needs periodic boosts every few months because of atmospheric drag. 100 km is nowhere near high enough to escape the Earth's atmosphere completely.
Jun
14
comment Why does a black hole have a finite mass?
Note that not all theories explain a black hole as a singularity. There are some exotic ideas out there, but in some cases the black hole is simply extremely dense, but not necessarily infinitely dense (but still dense enough to have an event horizon). The singularity arises from relativity.
Jun
13
comment What do the colors in false color images represent?
To go along with both Eric's and Tigran's explanations, this image shows the color mappings of the famous image of the Eagle Nebula. Notice that the colors used (blue, green, and red) don't exactly match the colors they represent. A true color image, on the other hand, is very different (mostly red due to H-alpha). Still, your eye isn't sensitive enough to perceive this color.
Jun
13
comment Does the Moon's core still contain significant heat?
Instead of commenting on your answer, you should just edit it to include more info.
Jun
13
comment Calculations of apparent magnitude
Good point on the bolometric luminosities - the B-V index of Vega is indeed quite low (listed as 0.00 on Wikipedia, actually).
Jun
12
comment What happen when two galaxies collide?
Galaxies aren't mostly gas and dust. Most of their mass is contained in dark matter. Furthermore, most of the luminous mass is contained in stars.
Jun
12
comment Shapes of galaxies
This answer isn't very accurate. First of all, population III stars did not turn into supermassive black holes- they were perhaps larger than the largest of current stars, but not by much. Also, the supermassive black hole model is simply one idea of galactic formation. Scientists are still trying to see if the black hole formed before or after the galaxy, or if they formed concurrently. Finally, the explanation on why galaxies have their shape is wrong. There are multiple explanations, but each follow either a top-down or bottom-up approach.
Jun
9
comment Binary stars' apparent magnitude
@Jonathan: No way. Stars are opaque to light- in fact, it takes an extremely long time (on the order of hundreds of thousands of years) for the light from the core of our own Sun to make its way out to the surface. It is only from the surface that they can propagate in the vacuum of space.