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Comment: Re:He got it coming (Score 2, Insightful) 643

by ChowRiit (#30155960) Attached to: Vulgar Comment On Newspaper Site Costs Man His Job

I don't think the main point of the outrage is that he lost his job, but rather that the journalist in question violated his website's own privacy rules and then gloated about getting the guy in trouble. I'd simply expect better from a journalist (although, in retrospect, with people like UK tabloid journalists and Fox News I'm not sure why), and I think that violating someone's privacy and then gloating about it is outrageous.

I do hope they fire this journalist, but I somehow doubt it.

Comment: Re:You're accidentally correct (Score 1) 849

by fireylord (#30142114) Attached to: Can We Really Tell Lossless From MP3?

The problem with any digital format is the that the sound is broken up into discrete bits. Even a lower quality vinyl can feel rounder and more 3d than a high quality digital recording.

poppycock, any attempt to label an audio format as poorer because it uses 'discrete bits' (aka a digital distribution) rather than an analogue format is just deluded, and misrepresents the science of audio

Comment: Re:Black holes are fiction (Score 2, Informative) 314

by ChowRiit (#30090690) Attached to: Micro-Black Holes Make Poor Planet Killers

Short answer: because the escape velocity is greater than the speed of light inside the Schwartzschild radius, matter cannot travel outwards, but also cannot stay stationary (to prove this properly you need some fairly complex general relativity). Because of this it can only head towards the centre of mass, so the matter all converges on a single point. As the escape velocity only increases as one gets closer to the centre, this forces all the matter into a single point of spacetime, the singularity.

This is, at least, what general relativity tells us. However, it's impossible to know for sure, as one of the properties of black-holes is that it is considered impossible for information to escape the event horizon.

Comment: Re:Black holes are fiction (Score 3, Informative) 314

by ChowRiit (#30086606) Attached to: Micro-Black Holes Make Poor Planet Killers

Ah, but that's not the case.

On small scales, that is true. However, take the moon. Electromagnetically it's neutral, however it exerts a sizeable gravitational pull. As the Schwartzchild radius is proportional to mass (not mass squared or cubed, but mass), if one took instead 8 moons and packed them together in a cuboid arrangement, the mass has increased eight-fold while the radius has only doubled. Therefore if we keep adding mass, there will come a point when the Scwarzschild radius is larger than the radius of the huge moon-array and therefore the whole moon-array has an escape velocity greater than the speed of light and is therefore a black-hole.

Now imagine if all those moons are positively charged - it still doesn't matter, because no matter the strength of the outward force it cannot give them a velocity greater than that of the speed of light, so they remain a black-hole.

Gravity is so significant on large scales precisely because of this - with no negative charge, gravity is the most significant force at large distance scales.

Comment: Re:can we use a micro-black hole to power a starga (Score 3, Insightful) 314

by ChowRiit (#30086424) Attached to: Micro-Black Holes Make Poor Planet Killers

Black-holes are not a source of energy (excluding the monumentally tiny energy output via Hawking radiation), any energy gained harnessing black-holes would be from the accretion disk around them in which particles accelerating towards the black-hole emit radiation due to friction among themselves. However, you'd likely need a stellar-mass black-hole to get a realistic accretion disk going.

Anyway, ZPMs aren't hard to find, you just need Ancient-built replicator civilisations or time travel.

Comment: Re:The problem is... (Score 2, Insightful) 314

by ChowRiit (#30086382) Attached to: Micro-Black Holes Make Poor Planet Killers

To answer point 2, current evidence is that human radio signals will be distorted by the heliopause at the edge of the solar system such that they are undetectable from outside. Therefore, an incredibly strong and likely custom-built communication system would be needed to penetrate deep space and be detectable by aliens.

Secondly, while the Universe might be vast, we can only really stand a chance of picking up signals from within the Milky Way (and even then only fairly nearby, excluding stupendously powerful transmitters, perhaps), so the number of stars that could potentially signal us is vastly reduced.

Lastly, you have to limit that to only stars with habitable planets on which life has formed and evolved to a high level than ours, and then transmitted signals of sufficient power that reached Earth during the 50 or so years we've been listening.

Don't get me wrong, I think it's well worth using SETI etc to look but I don't think we should be shocked that we haven't found anything.

Comment: Re:Black holes are fiction (Score 1) 314

by ChowRiit (#30086294) Attached to: Micro-Black Holes Make Poor Planet Killers

It's perfectly possible to pack matter into it's own Schwartzchild radius, that is the radius at which the escape velocity from the collective body is greater than the speed of light. Once the escape velocity is greater than the speed of light, nothing can escape and so a black-hole is by definition formed.

If you're really interested, you really need to study General Relativity to properly prove the plausibility of their existence.

Comment: Re:Evaporate? (Score 5, Informative) 314

by ChowRiit (#30086206) Attached to: Micro-Black Holes Make Poor Planet Killers

Particles. A hand-waving description of what happens is as follows:

Pairs of particles (one matter, one antimatter) form randomly near the event horizon. One quantum-tunnels out of the black-hole and so appears to an observer outside the black-hole to have been emitted. Therefore, to conserve energy, the other particle must have negative energy and thus the black-hole loses a tiny parcel of energy (and thus mass).

The main point is that, because the particle was formed near the event horizon and didn't come from the black-hole itself, it carries no information out - thus, while the black-hole loses mass, no information can escape.

Comment: Re:Do they mean a black hole or a singularity? (Score 3, Informative) 314

by ChowRiit (#30086144) Attached to: Micro-Black Holes Make Poor Planet Killers

A black hole is any body tightly packed enough that its escape velocity is greater than the speed of light. Because material, as a result of this, can ONLY travel towards the centre of mass (outward travel, sideways travel and staying stationary are all forbidden this therefore HAS to form a singularity, as matter is all forced to head towards and occupy a single point.

The distance from the object where the escape velocity drops below the speed of light is the event horizon (aka the Schwarzschild radius), within this sphere* no light can escape so we call this sphere the black hole. In the centre of it is the singularity, which is the "true" black-hole.

All objects have Schwarzschild radii, however this radius is only a "real" radius if it exceeds the radius of the object. Wikipedia claims the Schwarzschild radius of the Earth is 9mm, so Earth would form a black-hole itself if it were compressed to smaller than 9mm in radius.

The key point is that a "black-hole" is not an object, per se, but a region of space from which light cannot escape. The "object" would be the singularity in the centre. From outside the black-hole, there's no real difference from a star of the same mass in terms of gravity.

*rotating black holes have a slightly different shape, depends on the speed of rotation.

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