The heliosphere is basically a bubble in space, determined by the solar wind and the interstellar cloud surrounding the solar system. Now, given the distances involved it is not that strange that assume that the non-smooth (i.e. quickly varying) surface solar wind spreads out into something smooth. Since we lack data on the interstellar cloud we need to do some assumption there, preferably one with some symmetry since that makes calculations easier. Also, the actual article about this: http://arxiv.org/pdf/1011.4962 , mentions that small deviations from symmetry gives very different results. So, being no heliophysicist myself, I'd guess it's a case of the old "let's try the easiest case we can imagine first", which generally is the right way to progress until more data is collected. Besides, things tend to be smooth to some approximation so it is a decent bet.



In deed. Now, with a very massive black hole the tidal forces can become negligible and then unicornmeat would be free to traverse it in a non-ripped apart fashion.


There is a very interesting overlap as well.

Taken out of context, that's one of the strangest sentences I've read in a while.

He'd cross the event horizon but would eventually be ripped apart by tidal forces approaching the singularity for any wormhole-like adventures.

I'm sure I had something else in mind when I wrote that, but you are of course correct. In addition one is likely to encounter photons blueshifted to really unpleasant frequencies.

Aha! Though admittedly it would be a pretty brutal way to go



Now are you a physicist or is there an awesome book about this stuff that I'm missing out on?

I'm pretty poor on the knowledge of this stuff for a wannabe astrophysicist, especially the more theoretical parts. Can't wait to delve into some of the maths behind it though (for ten seconds until my brain implodes anyway).
I also just did a thermodynamics exam last night so you could say I've had other things on my mind...



Yeah I'm pretty fascinated by particle physics. No courses on it at my uni for some reason. Maybe I'll get an internship at CERN and learn all about it...

I don't read popular science books, but I doubt there's anything out there except for maybe a blurb here or there (likely how you heard about passing through ring singularities into other universes). Towards the end of your undergrad (if you've already had an introduction to general relativity) you could pick up Poisson's (incidentally also the discoverer of mass inflation) A Relativist's Toolkit. Probably the only textbook I've encountered that talks about black hole tunnels in some detail and has an explicit calculation for the Reissner-Nordstrom case (Kerr is a bit trickier and I doubt you'd find anything in a textbook).


The problem with this is that at the very least you need a couple of courses in non relativistic quantum mechanics first which are generally given towards the end of your undergraduate education and then this might be followed by an advanced undergrad/beginning graduate course in particle physics at the level of Griffith's An Introduction to Elementary Particles. To get into the subject in any real depth though you'd need a few semesters of field theory and then a thorough class on the standard model which you'd probably only have to do if you're a graduate student entering the field.

Relativist's Toolkit sounds rather interesting, thanks for the rec. Yeah the Kerr stuff does sound a bit obscure, that's why it stuck in my mind perhaps.

CERN I was joking about - that would be pretty amazing to do though.
Condensed matter and quantum optics seem to be the big things at my uni. I think I'll have a clearer idea of where my interests lie after this year when I'll have done some relativity and quantum as well.
I'm getting well acquainted with field theory too (that exam is on Friday). Text book was Feynman, but heavily supplemented by Griffith's Intro to Electrodynamics. I find him really good at my level.

Sounds like you've definitely had formal studies too after all that...


Not to derail the thread too much:
Did anyone manage to catch the lunar eclipse? I was up at 4:30 to see it darken but the light pollution in my area makes for pretty shitty viewing.

I wanted to see it, I eventually went out at 11 PM or so but it just started to rain, so there was nothing to see. I was really tired so I went to sleep.

Incidentally, I heard on the radio that Iran is planning to send a monkey into space, then later a human if all goes well with the monkey.

Well most textbooks will cover Kerr black holes, just not black hole tunnels or geodesics in Kerr.


I ment quantum field theory, something you'd likely only encounter in grad school. The Feynman lectures are pretty awesome but the only thing missing are problems. I haven't ever used any of Griffith's electrodynamics but his quantum mechanics book is awful. If you're ever forced to use it in a class definitely supplement with a better text.


Yeah, I'm currently a graduate student specializing in black hole physics.

My area got spectacularly fucked: after a bright, hot day, clouds covered the entire goddamn sky at around 8 pm and went away by 1 am - basically, they came, hid the entire eclipse while it was happening, and left. I was kind of expecting a huge middle finger nebula to manifest in the sky while we were at it. Fuck it.

Ah yeah, quantum field theory is going to be... challenging (awesomely challenging, if I get there). Surprise surprise Griffith's quantum book is my text next sem. Got a rec for that particular problem?


Awesome!




Yeah that's shit. That always happens to me when I want to go look at something cool (like that planetary alignment a couple of weeks back). Course with the light pollution and lacking a telescope I don't get to see much anyway...

I'm surprised this thread didn't come back up with the whole space shuttle retirement thing, oh well.

I think this is pretty cool, the maths of shooting something into orbit around something as small as an asteroid (Admittedly a big one) out beyond Mars is mind boggling to me.

http://www.nasa.gov/mission_pages/dawn/ ... 10716.html

Heh I probably killed the thread with all the talk about textbooks...
Yeah uni holidays hit and I haven't been around here much. Funny how that happens when there's no study to do.
Completely missed the shuttle launch somehow, but it is a bit surprising that no one mentioned it here.

This picture is now famous: http://www.flickr.com/photos/85253481@N00/5921961525

And yeah, was reading about Vesta yesterday. Would be great to be involved with something like that.
That whole concept of slingshotting spacecraft from planet to planet is fascinating too, though I wouldn't like to be responsible for the maths behind it!

Cool news:

http://www.bbc.co.uk/news/science-environment-14307987

Offers some interesting possibilities for both unmanned and manned space travel.

It's better than nothing. I remember when Wise started they announced that they might find brown dwarves closer to Earth than Proxima Centauri, they made it sound like a real possibility, made a big deal out of the story. I don't know how far they are with the evaluation of Wise's data, but it appears they found nothing of the sort. Would have been really cool though, to have a thus far unknown star only about a lightyear away, would have presented a real possibility for sending a probe to another star. But who knows, maybe something of the sort is still hidden in the heaps of data Wise gathered.

The Opportunity rover is now (last update July 28th) only 500 meters away from the rim of Endeavour crater. I predict that it will be reported to have arrived with the next update (August 4th) since it normally drives about 500 meters per week, or at the very latest the update after it (August 11th). Stay tuned, after months of boring driving it will finally have reached its exciting goal.

http://marsrovers.jpl.nasa.gov/mission/status.html

Hubble Discovers a New Moon around Pluto


From the NASA site





http://1.bp.blogspot.com/-SFVh7yvTadM/T ... uto_02.jpg

It has its own Wikipedia page already: http://en.wikipedia.org/wiki/S/2011_P_1

Hooray for new discovery.

I hope you all are thirsty!

Haha, awesome. I think I remember seeing it on my Twitter. (Twitter's great for science news, who'd have thought?)
Quasars are really interesting things, this thing even more so! I hope to research that kind of stuff one day...



Seems like Pluto's making up for its demotion by trying to catch up with the real planets.
I think I remember a couple of weeks ago you were going to be able to see Hydra cross in front, but I don't have access to a good telescope anymore.

Did you hear that it was Neptune's birthday a week or two back? Meaning one Neptunian year has passed since it was first discovered: http://www.wired.com/wiredscience/2011/07/neptunian-year-birthday/

Umm... You've actually had access to Hubble at some point?

Wow.

Should have read over that post before posting. I'm always doing shit like that. It wasn't crossing in front of Pluto, it was an occultation of a star.
So you point your telescope at that star and wait for it to wink out. Closest we're going to get to ever seeing Hydra (unless you have access to Hubble...)

http://www.bbc.co.uk/news/science-environment-14391929

I like this kind of theories. The very distant past is always subject to strangeness, and this particular theory is just that.

Unfortunately they don't give a theoretical timetable as to how long that moon might have "lived", or an estimate on its size.

Space always remind me of H.P. Lovecraft for some reason. It is very big, and I think that Lovecraft does an excellent job of conveying our puny existence in such a large place. Space is fucking cool though.

That's a cool one. I was speculating on what would happen if Earth had a second moon with some physics buddies not so long ago. Them crashing into each other was one of the more realistic theories...

That theory that the Sun has an undetected binary companion was a cool theory like that.

They mention microbes, I wonder about fungus. I wouldn't be surprised if you could find spores on Mars at least, seeing as they can survive space.

The whole 2nd moon deal and flowing water on Mars bit is quite exciting to think about. Hopefully we'll actually get to Mars some day and see for ourselves! I hope I'm alive for that, I'd love to see the headlines for that day. Alien life officially confirmed.

Water on Mars that would be something. Maybe it`s just deep erosion from dust storms producing shadow?

I`ve been thinking about the big bang after reading that our universe will eventually suffer a heat death. so what caused everything to start burning (reacting) producing this heat, I wondered if it wasn`t born out of an infinitesimally small compaction exploding but maybe two gigantic objects or even universes colliding?

Has this lecture been posted before? (There are a few hour long videos on this page).

http://www.youtube.com/watch?v=n19HIHCpOVE


Fastest space probe would take 10 000 000 yrs to reach the nearest star - Proxima Centauri

The heat death does not mean that stuff heats up. It's the opposite. Everything will eventually be at the same, very low temperature, and distributed evenly as individual particles or something to that effect. There will be practically no differences in temperatures in the universe, and no gravity wells once the black holes have vaporized. In other words, there's nothing that could produce ANY usable energy for any purpose, and any processes above occasional individual particles will simply cease. Including life, computing, and thoughts.

Corimngul knows this stuff better, and I think it's partially dependent on the decay of protons, which I believe is still theoretical. Anyway, not a nice future. Your offspring, should you have any, and no matter how good they are in it, hundreds of thousands of trillions of years from now, will cease to exist at some point due to this heat death, no matter what they do, and there's no hope of avoiding it. Don't have kids, dude. It's all in vain. Everything is doomed.

But the fact that we`re here maybe proves it`s not all doom and gloom? Maybe universes suffering eventual "heat death" (heat loss) have happened many times before? Maybe when heat death finally occurs it all starts over - how? well watching the lecture the scientist says that the universe is expanding and was expected to stop then contract back (producing another singularity), But they have found that is not so and it appears everything is actually speeding up, accelerating away which they put down to "dark energy" (different from dark matter). Maybe all matter travelling at colossal speed encounters other regions we yet know nothing about?



Amino acids from Nasa site

http://www.nasa.gov/topics/solarsystem/ ... acids.html

Of all the 'death of the universe' subjects I come across, it would be the '...........!' link on Exit Mundi http://www.exitmundi.nl/exitmundi.htm One googol year is not that bad a wait right?

i've read that the universe is basically sling shot outwards, like throwing a stone up, eventually the forces will pull it all back towards the start/beginning of it all again as it loses the initial velocity that shot it out to begin with collapsing in again on the single force at the center.

what goes up must come down.
what expands out must collapse in.



this idea makes me ask one question, where is the center and beginning of it all, and what must be there that threw all this spiralling outwards for billions of years and thus at some point to once again collapse back in some forgotten lifetimes later again.

that is where 42 must reside.

Antimatter belt around Earth discovered by Pamela craft
http://www.bbc.co.uk/news/science-environment-14405122

Distance to the first landfall of Endeavour crater is now down to 120m as of the latest update (August 4th), it will most definitely arrive some time this week. On a sidenote, the rover has now driven 33.23km total since the beginning of its mission.

Here`s a good site where you can see photos taken by the rovers pancam.


http://pancam.astro.cornell.edu/pancam_ ... color.html


I`m looking at a rock(?) on Mars, unbelievable.


http://pancam.astro.cornell.edu/pancam_ ... ue_RAD.jpg

Good, now all that's left is to find a good and safe way to permanently store antihydrogen.

Very interesting, I wonder what are the implications on a wider scale, if it interacts with some other phenomenon.