Follow Slashdot blog updates by subscribing to our blog RSS feed

 



Forgot your password?
typodupeerror

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

×

Comment: Re:Oh? (Score 1) 137

by Waffle Iron (#49137343) Attached to: 12-Billion-Solar-Mass Black Hole Discovered

If the matter is just "falling in" given the matter's density and distribution being less than 100% of the total possible space I think it's possible that your "maximum possible rate" is an artifact of a static model of a black hole at any given time. I think it's probably impossible that this rate was even approached, really, for any significant time period, certainly not "nearly its entire existence."

The amount of matter that fits in a given space is totally dependent on its pressure and temperature. For the conditions in an accretion disk near the surface of a black hole accumulating at its maximum rate, the space is at 100% of its capacity to hold matter.

Comment: Re:Oh? (Score 4, Interesting) 137

by Waffle Iron (#49137009) Attached to: 12-Billion-Solar-Mass Black Hole Discovered

"it must have been munching matter at close to the maximum physically possible rate"

That "maximum possible rate" sure sounds like bullshit.

Why does it sound like BS? Given that a huge fraction of the matter spiraling into the black hole is converted into energy before it falls in, that creates an outward pressure that limits how much more matter can follow. So there is a maximum rate that the black hole can accumulate mass.

Comment: Re:Gamma burst (Score 1) 202

by Waffle Iron (#49136675) Attached to: What Happens When Betelgeuse Explodes?

If you were to actually read some of the "literature", you would find out that your supposition is wrong. For example:

A GRB within a few parsecs that is directed at the Earth will impact one
hemisphere of the planet with a short, but intense blast of high energy
photons. Gamma rays and X rays are highly attenuated by the Earth’s atmosphere.
Therefore, the ground level effects are primarily indirect. A small fraction
of the incident energy reaches the ground as dangerous ultraviolet (UV)
radiation (Smith et al. 2004), but this is limited in time to the duration of
the event, which is at most 10’s of seconds for a long burst, and is less than
a seconds for a short burst. While it is possible that this flash would affect
some organisms, it seems unlikely that a biological catastrophe would result
from this effect alone. Of course, for planets with thinner atmospheres the
energy deposited at the ground would be greater and more serious effects may be
expected (Smith et al. 2004; Ga lante & Horvath 2007). We are concerned here
with effects on life on Earth and so will concentrate on the longer term
impacts.

There are three potentially harmful long term effects of a GRB that follow from
changes in atmospheric chemistry (Reid & McAfee 1978). High energy photons
cause dissociation, GRBs and Life on Earth ionization and ionizing
dissociations of N and O in the atmosphere. Subsequent reactions lead to the
formation of nitrogen oxides, most importantly NO and NO These compounds
catalytically deplete ozone (O3) in the stratosphere, leading to increases in
surface level solar UV over long time periods (years). Secondly, NO2 itself is
a brown gas that absorbs strongly in the visible. This may potentially have a
climatic effect by reducing solar insolation a t the ground, thereby leading to
cooling. Third, the atmosphere returns to normal via the removal of nitrogen
oxides by way of precipitation of nitric acid (HNO3).

What's more, it's not possible to "wipe out life on earth" in this manner given that some organisms have been found living in rocks a couple of miles down inside the earth. Instead, a mass extinction is the worst case outcome.

Comment: Re:Gamma burst (Score 1) 202

by Waffle Iron (#49127957) Attached to: What Happens When Betelgeuse Explodes?

No, the atmosphere would shield you from the gamma rays. However, a side effect of that would be the generation of massive amounts of ozone-destroying chemicals in the upper atmosphere. The subsequent lack of ozone and massive UV exposure would be the real risk, especially because almost all of our food grows in sunlight.

Comment: Re:The fuzzy line between hobby and job (Score 1) 216

The taxes collected are a redistribution of wealth from automobile drivers to truckers because trucks cause FAR MORE than four times the damage.

This is about the fourth time I've had to spell this out for you. Instead of reflexively reaching for your keyboard, start at the top of the previous paragraph and READ. IT. AGAIN. until it sinks in. If that's even possible for you.

You're also high if you think that the total tax and borrowed money spent on roads in this country is anywhere near covered by fuel taxes and fees.

Byte your tongue.

Working...