Science thread [merged]

[tiga]

The meteorite in Russia vision was impressive. Not great for the 1200 people it injured though. What surprised me was people filming it were so in awe they kept driving towards where it was coming in.

http://www.smh.com.au/technology/sci-tech/russian-meteorite-explosion-injures-1200-20130216-2ejim.html

I was watching one video last night where a bloke was filming the trail in the sky then the shock wave hit. Pretty awesome stuff. The universe is brutal

Online link dwaino?

[dwaino]

The meteorite in Russia vision was impressive. Not great for the 1200 people it injured though. What surprised me was people filming it were so in awe they kept driving towards where it was coming in.

http://www.smh.com.au/technology/sci-tech/russian-meteorite-explosion-injures-1200-20130216-2ejim.html

I was watching one video last night where a bloke was filming the trail in the sky then the shock wave hit. Pretty awesome stuff. The universe is brutal

Online link dwaino?

http://youtu.be/b7mLUIDGqmw  You only need to watch the start

[dwaino]

[mightytiges]

NASA, and plenty of private individuals, want to put mankind on Mars. Now a team at the University of Washington, funded by the space agency, is about to start building a fusion engine that could get humans there in just 30 days and make other forms of space travel obsolete.

The Fusion Drive Rocket system doesn't require conventional fuel. It uses magnetism to compress metal bands around a deuterium-tritium fuel pellet, with the resultant fusion ejecting the pellet and propelling the craft forward.

The system's comparatively low electricity requirements mean it could be run on solar power alone.

A pellet the size of a grain of sand would provide the same amount of thrust as a whole gallon of normal rocket fuel.

The fusion engine's unprecedented speed is really all that matters though. NASA's Curiosity rover took eight months to reach Mars using traditional engines. The fusion system could shorten that trip to just 30 days.

http://www.heraldsun.com.au/technology/sci-tech/scientists-developing-fusion-engine-which-could-make-space-travel-super-fast/story-fn5iztw3-1226618113290
http://www.theregister.co.uk/2013/04/10/nasa_fusion_engine_fast_mars_trip/

[Judge Roughneck]

NASA, and plenty of private individuals, want to put mankind on Mars. Now a team at the University of Washington, funded by the space agency, is about to start building a fusion engine that could get humans there in just 30 days and make other forms of space travel obsolete.

The Fusion Drive Rocket system doesn't require conventional fuel. It uses magnetism to compress metal bands around a deuterium-tritium fuel pellet, with the resultant fusion ejecting the pellet and propelling the craft forward.

The system's comparatively low electricity requirements mean it could be run on solar power alone.

A pellet the size of a grain of sand would provide the same amount of thrust as a whole gallon of normal rocket fuel.

The fusion engine's unprecedented speed is really all that matters though. NASA's Curiosity rover took eight months to reach Mars using traditional engines. The fusion system could shorten that trip to just 30 days.

http://www.heraldsun.com.au/technology/sci-tech/scientists-developing-fusion-engine-which-could-make-space-travel-super-fast/story-fn5iztw3-1226618113290
http://www.theregister.co.uk/2013/04/10/nasa_fusion_engine_fast_mars_trip/

erm...

[dwaino]

Some pommy scientists reckon they've found proof of extraterrestrial life.

http://mobile.news.com.au/technology/sci-tech/british-scientists-claim-to-have-found-proof-of-alien-life/story-fn5fsgyc-1226723186041

I hope they didn't come by boat.

[tiga]

Awesome!! an update on the Science thread! I love this science thread! 

[dwaino]

Four eyes 

[Judge Roughneck]

For the first time, the US government is estimating how many people die from drug-resistant bacteria each year - more than 23,000, or about as many as those killed annually by flu.

US warns of the growing threat of germs that are hard to treat because they've become resistant to drugs.

http://www.sbs.com.au/news/article/2013/09/17/drug-resistant-bacteria-were-facing-catastrophe

[mightytiges]

Stephen Hawking: 'There are no black holes'

Hawking does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.

In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.

http://www.nature.com/news/stephen-hawking-there-are-no-black-holes-1.14583

[dwaino]

I can't remember if it was his Into the Universe series or a Through the Wormhole, but they spent an episode on this where he thought the information was stored but completely scrambled.

[mightytiges]

I can't remember if it was his Into the Universe series or a Through the Wormhole, but they spent an episode on this where he thought the information was stored but completely scrambled.

One thing I'm still getting my head around on this is does this apparent horizon act effectively like an event horizon for massive black holes. The equivalence principle should mean (quantum) systems approach 'classical' physics in the large-scale many-body limit. Even with Hawking radiation, a black hole with mass equal to our Sun or greater barely radiates (so it effectively behaves as 'black').

[dwaino]

Honestly I struggle to grasp it myself. I was always understanding that the event horizon was simply the point of no return when entering a black hole. As a term I don't really see how Hawking's new theory does away with that at all. Something with so much mass is going to have just that effect. Going by just that article I think I'm with Polchinski on this one. With no disrespect to Hawking,  it wasn't that long ago really that he was absolutely steadfast that black holes did not radiate or lose info at all.

IMO I don't think that article is very well written. The title is misleading as are the headings. He's not doing away with black holes or the event horizon as we know it completely, and it almost suggests (as I interpret it anyway) that black holes chomp up matter then spew out Hawking Radiation and shed mass and energy, but this obviously cannot be the case. I was glad that when I read through the comments I wasn't the only one who thought so and that I wasn't just a total numpty (which is probably true though    I'm an 'armchair physicist' that watches nothing but science docos and reads both non-fiction physics and hard sci-fi )

[mightytiges]

Honestly I struggle to grasp it myself. I was always understanding that the event horizon was simply the point of no return when entering a black hole. As a term I don't really see how Hawking's new theory does away with that at all. Something with so much mass is going to have just that effect. Going by just that article I think I'm with Polchinski on this one. With no disrespect to Hawking,  it wasn't that long ago really that he was absolutely steadfast that black holes did not radiate or lose info at all.

IMO I don't think that article is very well written. The title is misleading as are the headings. He's not doing away with black holes or the event horizon as we know it completely, and it almost suggests (as I interpret it anyway) that black holes chomp up matter then spew out Hawking Radiation and shed mass and energy, but this obviously cannot be the case. I was glad that when I read through the comments I wasn't the only one who thought so and that I wasn't just a total numpty (which is probably true though    I'm an 'armchair physicist' that watches nothing but science docos and reads both non-fiction physics and hard sci-fi )

Yep you're right about the title being misleading (at least to a lay-person). An object being 'black' or not has a specific meaning in physics.

This is from Hawking's actual arXiv (archive) paper which this article is based on:

By CPT [invariance], the time reverse will be the CP conjugate. This shows that, in this situation, the evaporation of a black hole is the time reverse of its formation (modulo CP), though the conventional descriptions are very different. Thus if one assume quantum gravity is CPT invariant, one rules out remnants, event horizons, and firewalls.

The absence of event horizons mean that there are no black holes - in the sense of regimes from which light can't escape to infinity. There are however apparent horizons which persist for a period of time. This suggests that black holes should be redefined as metastable bound states of the gravitational field.

The no hair theorems imply that in a gravitational collapse the space outside the event horizon will approach the metric of a Kerr solution. However inside the event horizon, the metric and matter fields will be classically chaotic. It is the approximation of this chaotic metric by a smooth Kerr metric that is responsible for the information loss in gravitational collapse. The chaotic collapsed object will radiate deterministically but chaotically. It will be like weather forecasting on Earth. That is unitary, but chaotic, so there is effective information loss. One can't predict the weather more than a few days in advance

http://arxiv.org/pdf/1401.5761v1.pdf

[dwaino]

I think they need to start renaming this stuff because all they seem to be arguing now over is what actually makes up a black hole, or start calling his new 'black hole'  (or lack there of) something else until there is something more substantial to go on. To argue that one doesn't exist just means they need to give another name to something so dense that it distorts space time and doesn't reflect light/allow light to escape. In my mind I just picture black holes as something like a magnetar on steroids. Must be a slow news day in the physics world.

I have so much respect for Hawking. Sagan has long been my idol, then Hawking just behind and closely followed by Michio Kaku (yessss pop science  ), but it just seems like lately Hawking has been coming out with everything and anything to cause a bang in his twilight years.