Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Lagslayer]

Maybe the energy just can't escape the black hole. That's an awful lot of gravity, after all. And if matter is just condensed energy, then the energy should be affected similarly, because it's basically just faster and smaller.

[Gentlefish]

But where does it all go after the hole dissipates?

[Il Palazzo]

Regardless, all matter in the universe has not been consumed by black holes, so we can assume there is some element preventing rampant stable singularity formation.

The point being the same theories that predict black hole creation from high-energy collisions predict their evaporation. The lack of evidence for the latter weighs also on the former. The lack of rampant singularities can be simply due to them never having reason to exist in the first place.

Doubt it. From what we know, galaxies maintain their gravitational stability through having supermassive black holes at the center. I do not know of us having found any exploded/exploding galaxies.

While there is certainly no theoretical basis nor observational evidence(the explosions would be huge) for the black holes exploding after attaining "critical mass", the rest of the argument is contrived.
The central black holes have very limited effect on galaxies. A 1 million solar masses black hole contains mere 0.001% mass of the Milky Way. From 1000 ly away it's gravitational field is as weak as the Sun's from 1 ly. Additionally, from sufficiently far away, there's no difference between having a black hole at the centre and having an equivalent amount of regular stars distributed in the core.
Removing the hole would radically change the orbits of stars in its immediate neighbourhood. It would definitelly not destabilise the galaxy as a whole.

[Putnam]

But where does it all go after the hole dissipates?

The hole dissipated because it all went through Hawking Radiation.

[Bauglir]

You know how matter is super-condensed energy?

That's not... really accurate. It's a configuration of particles that happens to have mass, like (say) a photon is a configuration of particles that lacks mass. I'm not sure there's a meaningful interpretation of "super-condensed energy".

[Putnam]

Or something like that. The definitions of these things (particles and waves in particular) aren't quite fuzzy so much that words haven't been made to describe what they specifically are without the connotations of what we thought they were before.

[alway]

Or something like that. The definitions of these things (particles and waves in particular) aren't quite fuzzy so much that words haven't been made to describe what they specifically are without the connotations of what we thought they were before.

Or more accurately, no one here has bothered to read wikipedia articles relevant to the discussion.

It's less that matter is weird and more than most people have bullshit preconceptions about the nature of things. Crusty leftovers from the rotten corpse of Plato and similar, combined with a healthy dose of evolutionary baggage. Things simply aren't discrete, and a true lack of things simply does not exist anywhere. Time is not weird, it simply can have singularities and infinities; not really any more unusual than such a basic operation as a tangent function. Neither does time flow in one direction; it doesn't flow any more than space does, our meatspace brains simply happen to operate in one direction due to interesting emergent properties arising from things interacting.

All that aside, the X-Rays you observe from black holes is the result of the black hole feeding, not hawking radiation. Hawking radiation decreases rapidly with size, and so the larger a black hole is, the longer it lives. Supermassive black holes are expected to live on the order of 10^106 years or so. Or approximately 96 orders of magnitude longer than from the big bang to now. One with the mass of the sun would be around 10^66. Or around 56 orders of magnitude longer than the lifetime of our sun. By the time these decay, the entire rest of the universe has pretty much spun down to a high-entropy state in which the energy to even form a star has been gone for eons unimaginable.
The X-Rays you see are the result, not of this tiny trickle of energy, but from dust and such, accelerated to near light-speed, being all jostled and mushed together in a chaotic soup, then shot out in jets along magnetic poles.

[olemars]

British scientists develop a workable haptic feedback system based on ultrasound, that doesn't require you to touch anything except air:

Guardian article with cheesy headline.
Actual project website with videos and papers.

UltraHaptics employs focused ultrasound to project discrete points of haptic feedback through the display and directly on to users’ unadorned hands. We investigate the desirable properties of an acoustically transparent display and demonstrate that the system is capable of creating multiple localised points of feedback in mid-air. Through psychophysical experiments we show that feedback points with different tactile properties can be identified at smaller separations. We also show that users are able to distinguish between different vibration frequencies of non-contact points with training. Finally, we explore a number of exciting new interaction possibilities that UltraHaptics provides

Unadorned hands!

I can think of a few applications for something like this. One thing is combining it with 3D or the Minory Report gimmic, but it could also be a huge boon for blind people who now have to deal with shitty text-to-speech or rather bulky braille surfaces.

[Osmosis Jones]

Olemars, that is insanely cool. With tech like that, it's going to be a fun time to live, a decade from now.

Also, I didn't see it mentioned, so just a heads up; in news that will surprise absolutely no one, Peter Higgs and Francois Englert have won the Nobel prize for physics.

[10ebbor10]

It's a sad thing the other guy died 2 years ago though.

[Baffler]

Please don't be a hoax, please don't be a hoax!

[10ebbor10]

Please don't be a hoax, please don't be a hoax!

It's not a hoax, it's an grave overstatement.

As stated a few pages earlier, they don't count the inefficiency of their laser*. So no, fusion has not broken even yet. Only thing they did is getting more energy out of the reaction, than the thermal energy they put in.

*Which are quite large. In case of the National ignition facility, only 33% of the power put into the laser is actually emitted. And then there's the inefficiency of the absorption. Not all the energy is absorbed after all, a significant amount of light is reflected. Adding to that, at best only 33%-40% of the thermal energy can be recovered. (Not counting waste heat recuperation, as that doesn't produce electricity.)

[Baffler]

That's disappointing. I really should read back a few pages before excitedly linking whatever random thing I come across in the future.

[kaian-a-coel]

Please don't be a hoax, please don't be a hoax!

TL;DR:

Energy expended into firing the laser >> energy brought by the lasers to the pellet < energy generated by the pellet entering nuclear fusion.

That's still not "breaking even", but that's progress, and an important milestone indeed. Now we have to reduce the laser inefficiencies and/or increase the energy output ration by the pellet to the point that it offset the lasers' firing costs.

[10ebbor10]

The solution to neurdegeneration? (Also Alzheimer)