3,876 reputation
629
bio website physics.drexel.edu/~groenera/…
location Philadelphia, PA
age 27
visits member for 1 year, 6 months
seen Mar 21 at 1:19

I'm a Ph.D. candidate in the field of Physics at Drexel University. My research interests include the formation and structure of dark matter in galaxy clusters and gravitational lensing.


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Jan
18
reviewed Close Why do scientists think life requires water?
Jan
18
reviewed Leave Open Why does Mars' experience an 'ice age' at high axis obliquity, when Earth experiences an ice age at low axis obliquity
Jan
6
reviewed Leave Open Question: calculating orbit using another orbit
Jan
6
reviewed Leave Open Can Jupiter's bands be made out using a 15x70 pair of binoculars?
Jan
6
reviewed Close What are dark matter and dark energy?
Dec
26
reviewed Reopen What to look for in a tripod for binoculars?
Dec
23
reviewed Approve The role of gravity during planetesimal accretion
Dec
23
comment Can it be inferred that our cosmological horizon has increased over time?
Lastly, welcome to the astronomy stack exchange :) This is probably not deserving of a separate comment, but feel free to inject strict definitions of the cosmological and particle horizons (for those of us who worry about them), or clarify the language in my above answer.
Dec
23
reviewed No Action Needed Can A Black Hole Exist?
Dec
23
reviewed Leave Open Can Jupiter's bands be made out using a 15x70 pair of binoculars?
Dec
23
reviewed Approve Which galaxy is receding from the Milky Way the fastest? What is known of the mechanism behind its recession?
Dec
23
comment Can it be inferred that our cosmological horizon has increased over time?
You also incorrectly interpret my first point. I am not saying the speed of light is a hard cut-off in what we can observe, however, I am saying that since the universe expands (in a non-trivial way), and the speed of light is finite, there is a fundamental limit to how far into the past we can see. In other words, it DOES have to do with the speed of light. Your definition of the particle horizon is a rather poor answer, since you fail to make it understandable in any way.
Dec
23
comment Can it be inferred that our cosmological horizon has increased over time?
Firstly, I say "boring" because there weren't objects to look at in this stage of the history of the universe. People do study the swiss cheese universe at high redshift using radio surveys, but you are wrongly interpreting what I mean here, as stars and proto-galaxies have to have formed first - which is not what I am discussing here.
Dec
20
awarded  Custodian
Nov
2
reviewed Approve solar-eclipse tag wiki excerpt
Oct
30
awarded  Nice Answer
Oct
11
comment Which galaxy is receding from the Milky Way the fastest? What is known of the mechanism behind its recession?
There are a lot of unknowns about dark energy. However, typically, it is included into Einstein's field equations through the addition of a term called "the cosmological constant". If it is in fact supposed to be included in GR in this particular way (which it is absolutely not clear that it is supposed to be), then the interpretation is that it must have a negative equation of state. That's all I was saying below. Secondly, we have mapped out the large scale universe out to a fair distance - we do not live at the center of a void (unless the size of the void is that of the entire universe).
Sep
30
awarded  Explainer
Sep
24
awarded  Yearling
Jul
24
comment Could dark matter particles be unstable?
@Envite That is absolutely incorrect. Astronomer's do not define dark matter as cold gas, dust, or the like, which is simply unobservable.