Astrophysics and Cosmology - Discuss the Universe here

[Agent : Orange]

So am I correct in assuming that the thin line "inside" the black hole space is a lensing artifact?

Yes, you are correct. That's the equivalent of an Einstein ring for an accretion disk in strong field conditions. These lensed images get more complicated if the black hole is rotating or charged as well. The image posted shows the simplest case (Schwarzschild black hole).

[Agent : Orange]

Hopefully it's not one of those "fingerprint nebulas".   

lol!

[Agent : Orange]

This is pretty damned exciting stuff, wanna take a ride? 


http://www.bbc.co.uk/news/science-environment-25814454

That's a great story. Can't wait for November to see what comets are really like!

[Mind Flayer Monk]

It's possible you saw some of the galaxies in the Virgo cluster, which is around the constellation Berenice's Hair, and can be seen as diffuse nebulas (or you might have seen all the stars that make up the constellation itself, which is a kind of start cluster).  This would be below and to the right of the Big Dipper.  If what you saw was above it instead, you may have seen Bode's galaxies pair which is one of my fave objects to view, one being edge-on one being top-down.

Thanks Zeebo. I am sort of lost on all of this, but I will look it up.

[zeebo]

Thanks Zeebo. I am sort of lost on all of this, but I will look it up.

Came across this link to free astronomy software.  Check out the planetariums (planetaria?).  I use one that came with my 'scope and would be lost without it.

[Agent : Orange]

Came across this link to free astronomy software.  Check out the planetariums (planetaria?).  I use one that came with my 'scope and would be lost without it.

Thanks for posting!

[Agent : Orange]

Coincident with the recent discussions of black holes in this thread, Stephen Hawking no longer believes that event horizons are inescapable. An interesting discussion to be found here:
http://www.newscientist.com/article/dn24937-stephen-hawkings-new-theory-offers-black-hole-escape.html?full=true#.UueKC7Tna72

[zeebo]

Coincident with the recent discussions of black holes in this thread...

Hey Agent, I'm always hearing how the laws of physics "break down" in a black hole.  I guess you end up with weird infinities and things divided by zero or whatever.  But has anyone postulated that maybe there's a totally different kind of physics going on in them altogether - say maybe one that obeys a totally different kind of spacial geometry or such? 

I've heard of the idea that other universes may exist with different laws, and ours is perhaps just accidentally one where it worked out such that galaxies and planets and life could form.  So maybe inside a black hole are a diversity of other weird physics systems that are unrelated to ours?

[Agent : Orange]

Hey Agent, I'm always hearing how the laws of physics "break down" in a black hole.  I guess you end up with weird infinities and things divided by zero or whatever.  But has anyone postulated that maybe there's a totally different kind of physics going on in them altogether - say maybe one that obeys a totally different kind of spacial geometry or such? 

I've heard of the idea that other universes may exist with different laws, and ours is perhaps just accidentally one where it worked out such that galaxies and planets and life could form.  So maybe inside a black hole are a diversity of other weird physics systems that are unrelated to ours?

There are two places that general relativity stops making sense, this is inside a black hole (at the center of a non-rotating black hole for example) and at the very origin of the universe. In both of these situations the mathematics of GR diverges, like dividing by zero, and gives an infinite answer for the curvature and therefore also the strength of the gravitational field there. These points are "singularities", which really just means there's an infinity at those spots (ie, something bad happens to the math there) an these singular points are taken as an indication that our understanding and mathematical description of gravity, space and time at these points are not correct or complete. The currently accepted picture is exactly as you say: we expect that under extreme conditions like those at the center of a black hole or the beginning of the universe that general relativity is superseded by a higher theory, which is called quantum gravity. In this full theory quantum effects are expected to get more important as you go to very small scales and would hopefully do away with the singularities - instead of exactly zero there's some tiny "correction" which will prevent the answer from being infinite - but no one yet knows what this theory is or what the details of it are. String theory and Loop quantum gravity are two proposals to do away with the incompatibility of quantum mechanics and general relativity, but they are untested and there's really no consensus on these ideas in the scientific community despite what their proponents would say, the success of each will change depending on who you ask and what day it is.

The relationship between quantum gravity and general relativity should be a lot like the relationship between Newton's gravity and general relativity. In GR when we take the weak gravitational field limit and demand observers move with slow speeds with respect to the speed of light (appropriate for the gravitational fields around the Earth and the Sun for example), GR looks almost exactly the same as Newton's theory with a few slight but super important differences. For example, the weak field limit of GR predicts gravitational lensing effects to be twice as strong as you'd expect from Newtonian gravity, and also that objects near to the Sun should behave in a subtly different way. Lo and behold when you perform a measurement of how much starlight is deflected around the limb of the Sun during a solar eclipse you find exactly the predicted value by Einstein and not Newton (Eddington did these observations in the eclipse of 1919 and again in 1922 and it has been done many times since. The precision using radio interferometers is now good enough to see the effect of Jupiter lensing the light of background quasars as it passes by them in it's orbit around the Sun). Also the deviation of Mercury's orbit, which was a mystery under Newtonian gravity is taken care of by GR which gives the precise amount of deviation that should be (and is) found from watching how Mercury moves around the Sun. These solar system tests of GR are extremely convincing especially since they have been verified to such high precision. Just like GR "contains" Newtonian gravity in the weak field and low velocity limit, we expect that the next theory up the ladder will "contain" GR within it in an analogous way, such that we could take an appropriate limit (ie, on large distance scales) and recover GR the same way GR coughs up Newtonian gravity under the right circumstances. The weak field limit of GR has subtle differences than Newton's predictions and that's how we originally verified that GR was right. The problem is, we don't have observations of similar deviations from GR - which has so far passed every test thrown at it with flying colors -  so we don't know which quantum gravity theory is the right one since we can't test them in the appropriate limit. That's why binary pulsar systems and gravitational waves are so important, for example. These kinds of phenomena put strong constraints on how GR must behave if it is a description of the real world. If we see any deviation then we know there is a crack in the foundation of the theory and there is an opportunity to test quantum gravity. As I say, so far no faults have been found, and a lot of people are frustrated about that.

The hope is that once the right quantum gravity theory is found we will also gain insight on two other (separate?) mysteries that we don't understand right now, which are dark matter and dark energy. It's not clear if these aspects of the universe are evidence of additional components of the universe or if they represent cracks in the foundations of GR. I've mentioned earlier in the thread that there must be some kind of dark matter for our understanding of the universe to be consistent at a basic and fundamental level from a variety of separate and independent lines of inquiry, so there exist strong arguments that exist that these are extras which must be added to GR to make our understanding consistent. We would hope that quantum gravity will at least have something to say about these mysteries, and it may be that quantum gravity will give some effects that exactly mimic these components while changing some fundamental descriptions. No one knows. Regardless of what it has to say about these other things, it is definitely needed to sort out once and for all what happens when GR "breaks down".

[zeebo]

...We would hope that quantum gravity will at least have something to say about these mysteries, and it may be that quantum gravity will give some effects that exactly mimic these components while changing some fundamental descriptions. No one knows. Regardless of what it has to say about these other things, it is definitely needed to sort out once and for all what happens when GR "breaks down".

Thanks for the answer Agent, very deep physics at work here indeed. 

[gx2music]

thanks for this thread.
anytime i hear Noory interviewing some crackpot about "the electric universe" my faith in humanity diminishes a lot.  this thread restores it.

[valdez]

     Speaking of gravity; this is Felix Baumgartner's space jump.  Very cool.

http://youtu.be/dYw4meRWGd4

[Mind Flayer Monk]

thanks for this thread.

Thanks for the answer Agent, very deep physics at work here indeed. 

Yes, thank you for your time Agent:Orange. I appreciate it very much. Reading all the responses and questions is very interesting.

[Agent : Orange]

     Speaking of gravity; this is Felix Baumgartner's space jump.  Very cool.

http://youtu.be/dYw4meRWGd4

Nice!!

[zeebo]

I'm just hearing about this now, maybe others have come across it already.  A supernova was recently discovered in M82 and is apparently still viewable in amateur telescopes.  This galaxy is also known as the Cigar Galaxy and is part of the M81/M82 pair of galaxies which is one of my favorite objects I've viewed.  Unfortunately I can't get out to dark skies to see this before it flares out but maybe someone here can give it a try. 

(Btw the discovery was a fluke.  An astromomy professor just happened to pick that galaxy that night to demonstrate to some undergrad students how to use the school's telescope camera, and they noticed what looked like a bright star that wasn't in earlier images.)

Sky and Telescope article
Wikipedia article

It's circled in the picture below if you expand it.

[attach=1]

Credit: NASA/Swift/P. Brown, TAMU

[area51drone]

I try not to post in this thread, because as I see it, Jazmunda killed it.  But, here goes nothing:

http://www.dailymail.co.uk/sciencetech/article-2552530/The-mystery-North-Star-Astronomers-baffled-Polaris-getting-BRIGHTER.html

[Agent : Orange]

I try not to post in this thread, because as I see it, Jazmunda killed it.  But, here goes nothing:

http://www.dailymail.co.uk/sciencetech/article-2552530/The-mystery-North-Star-Astronomers-baffled-Polaris-getting-BRIGHTER.html

Bahahaha! Thanks for that avatar.

Cannot unsee

[area51drone]

Bahahaha! Thanks for that avatar.

Cannot unsee

You are very welcome.  I'm just glad someone enjoys my work.

[Agent : Orange]

http://phys.org/news/2014-02-chances-particle-collider-strangelets-earth.html

Move over, LHC! The next wave of unfounded fear-mongering will be from making strange matter at the RHIC. In the meantime, remember: it's spelled C-A-R-N-I-V-O-R-A

[area51drone]

Hmmm..... very interesting Agent.  Interstellar plasma mentioned in this article...

http://www.space.com/24692-mysterious-energy-ribbon-solar-system.html

Or is it just a cosmic string? 

[Agent : Orange]

Hmmm..... very interesting Agent.  Interstellar plasma mentioned in this article...

http://www.space.com/24692-mysterious-energy-ribbon-solar-system.html

Or is it just a cosmic string? 

lol!

Well there would be ways to prove it. Just look at the way distant objects are gravitationally imaged by the string!
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2004ASPC..314...46S&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

Some folks even thought we had found one too using this method until Hubble shot that dream down in 06:
http://arxiv.org/abs/astro-ph/0603838

But I still have hope that I will meet Bill Shatner on a cosmic string one day...

[Agent : Orange]

Hey science geeks. Are any of you guys able to identify this phenomena? The sun had a really cool rainbow ring around it today. I've never seen this before.

Going back to this again, I saw both sun dogs this morning, and if I squint I tell myself I can see the ring as well:

[Camazotz Automat]

It's that time again.

They're coming to take me away.

Ha Ha
Hee Hee
Ho Ho

http://www.calculatorcat.com/moon_phases/phasenow.php

[area51drone]

lol!

Well there would be ways to prove it. Just look at the way distant objects are gravitationally imaged by the string!
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2004ASPC..314...46S&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

Some folks even thought we had found one too using this method until Hubble shot that dream down in 06:
http://arxiv.org/abs/astro-ph/0603838

But I still have hope that I will meet Bill Shatner on a cosmic string one day...

I was joking about the string.   I'm surprised this is supposedly a real theoretical phenomena though.   I was more interested in the interstellar plasma comment in that article.

[Agent : Orange]

I was joking about the string.   I'm surprised this is supposedly a real theoretical phenomena though.   I was more interested in the interstellar plasma comment in that article.

Yeah, I know you were joking but it reminded me of actual cosmic strings, which are actually pretty cool to think about.

[Camazotz Automat]

The reboot of COSMOS on Fox with Neil deGrasse Tyson looks like it might be good. 

Any thoughts, Agent : Orange? Or anyone else lurking here?

(btw, when cosmic strings were mentioned, my mind went to the Threadfalls on Pern. hahaha)

[steelbot]

The reboot of COSMOS on Fox with Neil deGrasse Tyson looks like it might be good. 

Any thoughts, Agent : Orange? Or anyone else lurking here?

(btw, when cosmic strings were mentioned, my mind went to the Threadfalls on Pern. hahaha)

I can't wait to watch it.  I am interested only slightly in his sometimes dumb'ed down portrayal of the science, but Sagan did it too.  I'll watch and enjoy as anything with universe in the titles or having to do with it, gets my viewing.  Plus i don't mind Neil's way of selling it to people.  He's made it a very successful career.

[Agent : Orange]

I don't really know what to say about the new Cosmos yet. I'm hopeful, but a number of things raise red flags for me.

The original was well paced and thoughtful, the trailer for this one makes it look like a music video or action movie or something. The number of jolts per minute seems high compared to the mellow vibe of the original.

NDT is alright, he's no Carl Sagan but he can follow in Sagan's footsteps if he has the material to work with. I have no problem with him as host, but there are other factors that made the original so memorable for me beyond Sagan, and I just don't know if those aspects can be fully recaptured. The original was profound and dream-like, and the Vangelis soundtrack worked perfectly. Without this atmosphere, why use the "Cosmos" brand in the first place? The production has a lot to live up to and may have kneecapped itself by associating so closely with the such beloved source material. I feel like it may have made more impact on it's own as a show for NDT rather than trying to live up to an impossible legacy.

I guess I'm worried it's going to be "Cosmos for Gamers", produced by FOX. That may be a cheap shot at the producers but it does make me nervous, even with Ann Druyan involved. I would feel better about the whole thing if it had a PBS logo at the end of the trailer. Maybe a personal bias, we'll see. Right now I can only comment on the trailer so I hope that it lives up to all it can be.

[Camazotz Automat]

... I guess I'm worried it's going to be "Cosmos for Gamers", produced by FOX. That may be a cheap shot at the producers but it does make me nervous, even with Ann Druyan involved. I would feel better about the whole thing if it had a PBS logo at the end of the trailer. Maybe a personal bias, we'll see. Right now I can only comment on the trailer so I hope that it lives up to all it can be. ...

Excellent response. You bring up a good question. Why call it COSMOS in the first place? I assume it is to attract fans of the original, but the hardcore fans may not appreciate crammed video and CGI to nth power.

I'm hopeful nonetheless.

Worse case scenario, even if I hate it, I imagine it will still be light years ahead of  yet another "reality TV" series.

And FOX gets points for trying. Or Seth McFarlane gets points for talking FOX into it at all.

I agree, it will be strange not seeing the PBS logo. I'm also not looking forward to commercial interruptions.

I may really be getting into it and BAM!, a mattress store commercial...

So harsh to the buzz.

I am interested only slightly in his sometimes dumb'ed down portrayal of the science...

And yet, he will never dumb things down to the level of asking one to trust a tarot reading.

(I'm joking, Steelbot.    I appreciate the function of the tarot from a Jungian synchronistic aspect and value the represented archetypes, etc, and own several decks.)

[zeebo]

Agent I have the same worries, that it'll be more about flashy effects and less about deep ideas.  The original Cosmos for me was not only scientifically fascinating but a poignant, thought-provoking experience that still resonates with me. 

I mean to me it's the greatest story ever told - the story of how the universe with it's stars and galaxies and life, came to be, and further, how we came to figure out how it happened (the story within the story). 

I hope they at least try and follow the spirit of the original instead of just capitalizing on the name.  I like NDT's enthusiasm and sense of humor but I'm not sure if he's got the gravitas for this one.  In any case, I'm sure I'll watch it as there will be updates to some of the original topics if nothing else.