Astrophysics and Cosmology - Discuss the Universe here

[West of the Rockies]

Every thread on this forum has been invaded with insanity.   There's no hope for bellgab.  It is doomed.

This thread is one of the reasons I DO come back...  But, yes, this one, too, is now tainted by lunacy.

[Mind Flayer Monk]

shark youtube video

Hmm how about the Kraken or a giant squid?

Other than that I know Killer Whales will eat sharks fairly regularly. They like to eat the livers of sharks.

I just found this memorable quote:
"In another instance, a great white approached two orcas while they were eating a seal. Not only did he end up having the shit kicked out of him, but also one of the orcas took the shark to the surface and, no shit, held the shark there while the other disemboweled it, feasting on its liver."

[West of the Rockies]

With some fava beans and a nice chianti?

[zeebo]

I didn't realize near-earth space was so crowded.

http://www.alexras.info/code/orbital_objects/

[area51drone]

http://youtu.be/Z_QyGANCUJI

I didn't watch it, but I'm guessing a supernova.

[Agent : Orange]

I didn't realize near-earth space was so crowded.

http://www.alexras.info/code/orbital_objects/

This link is so cool!!

I heard a talk by a scientist from NASA that was trying to come up with ways of capturing rogue objects, including some interesting methods using nets (http://thediplomat.com/2014/01/japan-will-cast-a-magnetic-net-for-space-junk/) and lasers (http://www.newscientist.com/article/mg22129602.200-australia-hatches-plan-to-zap-space-junk-with-lasers.html#.U5UW1ShUpv8). But I have never really had a feeling for just how busy low Earth orbit really is, that link really makes it clear.

[area51drone]

This link is so cool!!

I heard a talk by a scientist from NASA that was trying to come up with ways of capturing rogue objects, including some interesting methods using nets (http://thediplomat.com/2014/01/japan-will-cast-a-magnetic-net-for-space-junk/) and lasers (http://www.newscientist.com/article/mg22129602.200-australia-hatches-plan-to-zap-space-junk-with-lasers.html#.U5UW1ShUpv8). But I have never really had a feeling for just how busy low Earth orbit really is, that link really makes it clear.

I would like to know what's with that "ring" of satellites way out there.

[Agent : Orange]

I would like to know what's with that "ring" of satellites way out there.

That's where geosynchronous satellites live, like communications satellites. This is a common orbit for satellites because it allows them to stay overhead with respect to the Earth which is useful for many applications (http://en.wikipedia.org/wiki/Geostationary_orbit).

Edited to add http://en.wikipedia.org/wiki/Geostationary_ring

[zeebo]

That's where geosynchronous satellites live, like communications satellites. This is a common orbit for satellites because it allows them to stay overhead with respect to the Earth which is useful for many applications...

Neat ... I was curious about that as well.

[Agent : Orange]

This paper tries to explain the difference in the thickness of the lunar crust on the far side of the Moon and the hemisphere that faces us in terms of the giant impactor theory, the idea that a collision of a huge body (referred to as Theia) impacted the early Earth, and the remnants of this collision created the Moon. There has been a big surge of interest in the giant impactor model and a bunch of studies have come out recently that look for evidence of the collision (such as http://www.sciencemag.org/content/344/6188/1146).

http://arxiv.org/abs/1406.2020

Abstract: The lunar farside highlands problem refers to the curious and unexplained fact that the farside lunar crust is thicker, on average, than the nearside crust. Here we recognize the crucial influence of Earthshine, and propose that it naturally explains this hemispheric dichotomy. Since the accreting Moon rapidly achieved synchronous rotation, a surface and atmospheric thermal gradient was imposed by the proximity of the hot, post-Giant-Impact Earth. This gradient guided condensation of atmospheric and accreting material, preferentially depositing crust-forming refractories on the cooler farside, resulting in a primordial bulk chemical inhomogeneity that seeded the crustal asymmetry. Our model provides a causal solution to the lunar highlands problem: the thermal gradient created by Earthshine produced the chemical gradient responsible for the crust thickness dichotomy that defines the lunar highlands.

[Catsmile]

A good episode tonight on Nova, Earth From Space.
Running time, hour and fifty-two minutes.
Detailed satellite images reveal the web of connections that sustain life on Earth.

http://video.pbs.org/video/2334144059/

or check it out on GooTube.

http://youtu.be/38peWm76l-U

[Agent : Orange]

A good episode tonight on Nova, Earth From Space.

Thanks for posting, saw the show description but was not able to catch it live

[Agent : Orange]

New gravitational lens discovered by the Herschel observatory



Read the paper here:

3C 220.3: a radio galaxy lensing a submillimeter galaxy
http://arxiv.org/abs/1406.2872

Abstract: Herschel Space Observatory photometry and extensive multiwavelength followup have revealed that the powerful radio galaxy 3C 220.3 at z=0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z=2.221. At an observed wavelength of 1mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of 1.8" radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a powerful radio galaxy not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1.5", provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1.02") and B (0.61") are about 0.4 +/- 0.3 and 0.55 +/- 0.3. The mass to i-band light ratios of A and B, M/L ~ 8 +/- 4 Msun/Lsun, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CASTLES, LSD, and SL2S samples. The lensed SMG is extremely bright with observed f(250um) = 440mJy owing to a magnification factor mu~10. The SMG spectrum shows luminous, narrow CIV 154.9nm emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a dust-enshrouded nucleus.

[area51drone]

The coolest video you will see this month:

http://www.cnn.com/video/data/2.0/video/tech/2014/06/13/orig-jag-nasa-hubble-timelapse.cnn.html

[Agent : Orange]

The coolest video you will see this month:

http://www.cnn.com/video/data/2.0/video/tech/2014/06/13/orig-jag-nasa-hubble-timelapse.cnn.html

Thanks for posting that amazing video!!
The detail in the images of V838Mon is really striking.

[Mind Flayer Monk]

Great posts a51 and A:O. Thank you.

[bigchucka]

This might belong here...

http://youtu.be/ShTm8MnUAjo

[b_dubb]

http://www.nytimes.com/2014/06/20/science/space/scientists-debate-gravity-wave-detection-claim.html?hp

[b_dubb]

http://www.pbs.org/wgbh/nova/next/physics/spacetime-might-superfluid-help-explain-gravity/

[Agent : Orange]

...

Both interesting articles. The BICEP2 results have been contentious for quite some time now and no one is really sure how any of that will shake out. It's such a complicated measurement and big claim it has to be confirmed. Will be very interesting to see what happens in a few weeks! Science in action.

The gravity claim is also very interesting. The analogy between fluid mechanics and gravitation has been made a few times before with interesting results, and just a few weeks ago there was speculation that gravity may show turbulent effects, just like a fluid (http://www.sciencedaily.com/releases/2014/06/140605155732.htm). But the space-time these guys use to do the simulations are not at all realistic, so the question is are these toy models pointing us in a direction which will be useful for making predictions of how the real world actually works? Or do these effects depend on the way the models are set up?

[Camazotz Automat]

Warning: Narcissistic rambling alert.

I will always be grateful to my college physics professor. I think we might have been only three weeks in and I had a question that was bugging the hell out of me. I may have mentioned this before somewhen on this forum. If so, I am going to repeat it:

"What IS gravity?" I asked during class.

He immediately recognized my frustration.  He didn't sugarcoat his answer with further descriptions of what gravity does or gravitational effects/laws, nor did he throw a vague "it's the warping of time and space" out there and expect me to consider it answered.  Those answers are like telling me what a horse IS by describing what a horse DOES at the racetrack, or even worse, telling me what a horse IS by declaring the existence of a racetrack!

No.

He rested his hands on that black lab table, leaned forward and with his thick table-matching black framed glasses somewhat sliding down his nose, said  "We.... really.... do... not....know."  (And he actually said it like that... spaced, deliberate, dramatic.)

Silence. You could have heard a neutrino hit a detection tank.

A classroom of young minds in front of him and he gave it to us straight. I have no idea if he realized how relieved I was to hear his response. As stated previously, the question was bugging the eternal fucking Hades out of me.

Many many years later I would hear Stephen Hawking say the same thing Professor P_____ mercifully told us.

I still sometimes get stuck in a loop contemplating the question and I have to forcefully shake myself onto a different vector of thought. Similar to trying to break a song or jingle that is replaying in my mind. (a song like "Valleri" for example after studying a guitar passage a ridiculous number of times. Heh.)

In 1999 I was in a degenerate AOL chatroom and I posed the gravity question. Someone immediately quipped, "gravity is the result of the warping of time and space."

I could have strangled him had I somehow had his throat beneath a hacked and reciprocating Nintendo power glove on the other end.

The universe is preposterous and designed by a trickster god who feels no remorse at our captivity.  Sometimes the only thing you can do is put Magical Mystery Tour on the platter and cue up I Am the Walrus.

Right about now I could use a helpful barb from Sardondi to augment my less than whistling swung sword. I'm a bit off my game this morning. But at least my heart is in it and I spilled it all over the stage in one of my favorite threads.

[attachimg=1][attachimg=2]

[bigchucka]

He rested his hands on that black lab table, leaned forward and with his thick table-matching black framed glasses somewhat sliding down his nose, said  "We.... really.... do... not....know."  (And he actually said it like that... spaced, deliberate, dramatic.)

Reminds me of part of the last episode of Cosmos that was on a couple weeks ago.  He explained that science sometimes doesn't pretend to understand things they don't really know... or something like that.

[Camazotz Automat]

Reminds me of part of the last episode of Cosmos that was on a couple weeks ago.  He explained that science sometimes doesn't pretend to understand things they don't really know... or something like that.

The final episode was my favorite of the series.

[Mind Flayer Monk]

The universe is preposterous and designed by a trickster god who feels no remorse at our captivity.  Sometimes the only thing you can do is put Magical Mystery Tour on the platter and cue up I Am the Walrus.

Right about now I could use a helpful barb from Sardondi to augment my less than whistling swung sword. I'm a bit off my game this morning. But at least my heart is in it and I spilled it all over the stage in one of my favorite threads.

"Alfred Habdank Skarbek Korzybski ([kɔˈʐɨpski]; July 3, 1879 â€" March 1, 1950) was a Polish-American philosopher and scientist. He is remembered for developing the theory of general semantics. Korzybski's work argued that human knowledge of the world is limited both by the human nervous system and by the structure of language.

Korzybski thought that people do not have access to direct knowledge of reality; rather they have access to perceptions and to a set of beliefs which human society has confused with direct knowledge of reality. Korzybski is remembered as the author of the dictum: "The map is not the territory"."
...Human beings cannot experience the world directly, but only through their "abstractions""
http://en.wikipedia.org/wiki/Alfred_Korzybski

[Robert Ghostwolf's Ghost]

The universe is preposterous and designed by a trickster god

And even though I understand the principle of gravity, I still don't understand how we can live on the side of a big ball without falling off. 

[area51drone]

"We.... really.... do... not....know."

That settles it Agent.  Like a bigfoot "researcher" who spends his life traversing the backroads instead of getting out in the bush for weeks at a time, you are wasting your precious life.   Unless you are devoting every neuron in that brain of yours to determining exactly what gravity is, you might as well give up now.

[onan]

I know exactly what gravity is... I am just not sharing that information with the likes of you cretins.

[Camazotz Automat]

I know exactly what gravity is... I am just not sharing that information with the likes of you cretins.

Oh wait, WWJD?

stab stab stab

(that's Jackstar, not Jesus)

[Agent : Orange]

A proposed intermediate scale test for General Relativity using galaxy velocities. Modified gravity theories change the effects of gravity at medium range scales, which should manifest in a different distribution of galaxy velocities with respect to one another than you would expect from vanilla GR. An observation of this effect would be a groundbreaking discovery.

http://phys.org/news/2014-06-gun-gravity.html

[Agent : Orange]

Like a bigfoot "researcher" ...

Well, that's it. I made a suicide pact that once I was compared to a 'Footer it's time for me to die. Cheers all. Keep your sticks on the ice.