

Giant body of water found in space, black hole claims it was just hydrating - bond
http://www.engadget.com/2011/07/23/giant-body-of-water-found-in-space-black-hole-claims-it-was-jus/

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redsymbol
The press release from JPL, which is more thorough and detailed:

<http://www.jpl.nasa.gov/news/news.cfm?release=2011-223>

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shaggyfrog
Thank you for the link. I didn't see it anywhere in the story. In fact, the
"NASA" link doesn't even leave the site -- it just goes to stories with that
tag!

Gruber had a story recently about attribution and credit that Engadget should
read: <http://daringfireball.net/2011/07/attribution_and_credit>

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LoonyPandora
There is a link to the press release[1] the bottom left, next to where it says
"source" - All Engadget posts have it in the same place. Seemingly it's not
prominent enough, but the attribution is certainly there.

[1]
[http://www.nasa.gov/topics/universe/features/universe2011072...](http://www.nasa.gov/topics/universe/features/universe20110722.html)

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shaggyfrog
While true, it looks identical to the "NASA" link that precedes it that
doesn't go externally, and so I skipped over it as I thought it was a
duplicate.

Besides, is it possible to make an attribution _less_ visible?

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mapgrep
What is the deal with the Engadget headline? Is it supposed to be a joke? The
black hole claims it was just hydrating? I'm trying to accept the silly/weird
premise in good humor, but I still don't "get" why the figurative humanish
black hole is defensive about converting water vapor to energy.

Maybe there's an obscure sci-fi or Seinfeld reference I'm missing.

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jackpirate
It's a <http://fark.com> style headline. No idea why engadget adopted it
though.

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mortenjorck
Engadget used to have witty headlines when they were covering something
legitimately funny or ironic. The writing had a sort of fun, Brooklyn street-
vibe to it that dated to when Peter Rojas ran the site.

Unfortunately, this headline is a perfect example of where Engadget has gone
in its AOL-Way, post-Topolsky era: trying to be funny by formula. It's mostly
missing the charm of the style it is ostensibly following.

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ashwinraghav
Its 12 billion light years away. Just keep in mind that this is what it looked
like 12 billion years ago => it takes the light 12 billion years to reach the
Earth. So the image as seen is really that old!

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goodside
That's not how it works. If we observe an object that's currently 12 billion
lightyears away (i.e., its co-moving distance is 12 billion light years) the
light we observe was emitted much less than 12 billion years ago. While light
is in transit, both the distances ahead and behind it will increase due to
Hubble expansion, so once you get up to cosmic scales like these the normal
distance/velocity formulas don't apply.

In general, if you point a flashlight into space and wait one year, the
distance between you and the photons of light will be _slightly_ higher than
one lightyear. As you wait longer, this difference becomes less slight. When
you get up to much larger scales (billions of lightyears) the Hubble expansion
dominates the equations.

In the most extreme cases, you get counterintuitive things popping up like
distances that are so large they can't be traversed in any amount of time,
even at light speed. Until you're using equations that make that seem natural,
you shouldn't rely intuitive calculations from NASA press releases like this.
Convincing science journalists of this fact is one of my minor life goals.

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riobard
So what's the actual time it takes for light to travel 12 billion lightyears?

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goodside
That depends greatly on when in the history of the Universe the light was
emitted. The scale factor varies over time. What you probably meant though was
"How long did the light that we're seeing from this particular quasar take to
get here?" That we can figure out.

When you get a problem like this one, the quickest way to get an approximate
answer is by interpolating from the following rule of thumb: If we see light
today that we know has been in transit since the start of the Universe (15.3
billion years ago), the point it was emitted from is now 46 billion light
years away from Earth. If you just assume that the impact of the Hubble
expansion is more-or-less proportional to the current distance of the object
in question, we can just linearly interpolate between the observed Universe-
scale answer and the intuitive Newtonian answer that applies on normal scales.

Newtonian answer: 12 billion years

Universe-scale answer: 12 Glyr * (15.3 Gyr) / (46 Glyr) = 4 billion years

Final approximation: 4 Gyr * (12/46) + 12 Gyr * (1 - 12/46) = 9.9 billion
years

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thyrsus
By "light today that we know has been in transit since the start of the
Universe" may I presume you mean the microwave background often referred to as
"remnants of the big bang"?

Where should I go to understand the derivation of the figure "now 46 billion
light years away"? It's not clear to me what you mean by "now" and "away",
since time and distance depend on the frame of reference, and it's not clear
to me what it means to be "at rest" in an expanding space. "At rest" enters in
because we're not going backwards in time, and thus we cannot reach the source
of the radiation (the event which generated the radiation at a specific space-
time coordinate), but only the event's spatial coordinates, and, absent other
specification, those spatial coordinates are "at rest" with respect to our own
frame of reference. But again, what does "at rest" mean in expanding space?

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iwwr
AFAIK, there is such a thing as a CMB 'rest frame' (the Earth-Sun is moving
relative to it at about 600km/s).

As for the weird distances, just imagine an ant moving across a rubber surface
at constant velocity. The rubber is slowly stretched over time, so while the
ant continues at the same rate it will actually cover less space. If the
rubber continues to stretch, there is an event horizon effect, meaning some
distant parts of the rubber sheet will become inaccessible.

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TeMPOraL
This article has just brought back to life my child faith that space hides
lots of amaing surprises for us. Thank you :).

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sgt
Could there be life inside of this water?

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loire280
According to the JPL article linked above, the water vapor is "300 trillion
times less dense than Earth's atmosphere." So it sounds like the cloud may as
well be empty vacuum as far as life is concerned.

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Tichy
What if it is an alien space ship that eats water, and it is coming for our
planet next?

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misuse-permit
Then we would have at least 12 billion years until they got here.

