antognini

125 ms·

1021.
by antognini 12y ago
Not really. Dark matter makes up so much more of the Universe (~25% dark matter vs. 5% baryons -- stars themselves are closer to .2%) in that even doubling the number of stars would not appreciably change the amount of missing mass. Moreo
1022.
by antognini 12y ago
No. Even if half of stars are outside the Galaxy, there are still enough stars within the Galaxy that the ideas behind the Fermi paradox would still be valid. This would be an explanation of the Fermi paradox if we were on a planet around
1023.
by antognini 12y ago
The free-floating planets result is still controversial and there is a substantial fraction of the astronomical community that doesn't believe it. If it is true, it introduces problems in our understanding of planet formation because
1024.
Montmort's Theorem(futilitycloset.com)
1 points by antognini 12y ago|0 comments
1025.
by antognini 12y ago
There's an interesting article on negative probabilities by Gábor Székely in which he shows that they can be generate by flipping a "half coin" -- a coin that, if flipped twice, gives the result from a single flip of an ordin
1026.
by antognini 12y ago
No, any photons that are emitted from matter close to the event horizon and travel toward the distant observer will be redshifted. Photons falling into the potential well of the black hole will be blueshifted. Of course, the distant obs
1027.
by antognini 12y ago
If the spacetime is static, then yes, the trajectory of a light beam (or anything else) is reversible. The question you pose is an excellent one and is one of the reasons that many physicists believed that black holes could not exist after
1028.
by antognini 12y ago
There is a well documented trend in the sciences away from research performed by scientists on their own or in small collaborations towards research performed by very large collaborations [1]. My understanding is that this has been going o
1029.
by antognini 12y ago
One of the reasons that there wasn't much in the way of development of larger telescopes in the late 1970s and 1980s was the development of the CCD. Prior to the CCD, astronomers used photographic plates to take their images, and phot
1030.
by antognini 12y ago
Yes, there is an index of refraction for gravitational waves passing through matter. As the gravitational wave passes through, particles in the material oscillate, producing their own gravitational waves. The combined gravitational wave f
1031.
by antognini 12y ago
Gravitational waves have not been directly detected by laboratory instruments here on Earth. The LIGO and VIRGO collaborations are looking for gravitational waves by using large laser interferometers, but haven't detected any yet. The
1032.
by antognini 12y ago
This is also true. The time allocation committee for the Hubble Space Telescope, for example, has a policy that projects are judged solely on their scientific merit, without any regard to the amount of time being asked for. This, of cours
1033.
by antognini 12y ago
Last year a professor in my department (astronomy) suggested that he and I write a similar tongue-in-cheek paper to be published on April 1. The idea was to promote a moratorium on new astronomical data for one year. This would give obser
1034.
by antognini 12y ago
Sure! In classical mechanics it's nice when you have a problem for which the solution is integrable. Oftentimes these solutions will also be periodic. One very useful example of this is an elliptical orbit---the object will return t
1035.
by antognini 12y ago
Many systems (including the Solar System) are stable over short time periods, but the stability of the Solar System is actually unknown over longer time periods. As an example, one of the numerical experiments Scott Tremaine has done has b
1036.
by antognini 12y ago
I work on other problems in three body dynamics, but I'm very pleased to see this article show up here on HN! One thing I could expand on a little is these singularities in Sundman's series. These singularities are nothing more t
1037.
by antognini 12y ago
It is possible! But how you go about doing it would depend on your goals, how much time you would have for it, and how much physics and math you know. The thing about astronomy is that it changes quickly, but not that quickly. The times
1038.
by antognini 12y ago
It's interesting that this has made it to HN! My research is on the dynamics of few body systems so I know OJ 287 well! One of the projects I've been wanting to work on but haven't gotten around to is about this system. As
1039.
by antognini 12y ago
The title, along with the rest of the article, seems to obscure an important point. Although the entangled particles appear to communicate with each other FTL, the observers can't communicate any information with each other this way
1040.
by antognini 13y ago
One of the great things about astronomy is that it's really one of the few fields of science where amateurs can still have a large impact. Most nearby supernovae are actually discovered by amateurs, not professionals (including one ju