90% of the Universe Found Hiding In Plain View

The Bad Astronomer writes "As much as 90% of previously hidden galaxies in the distant Universe have been found by astronomers using the Very Large Telescope in Chile. Previous surveys had looked for distant (10 billion light years away) galaxies by searching in a wavelength of ultraviolet light emitted by hydrogen atoms — distant young galaxies should be blasting out this light, but very few were detected. The problem is that the ultraviolet light never gets out of the galaxies, so we never see them. In this new study, astronomers searched a different wavelength emitted by hydrogen, and voila, ten times as many galaxies could be seen, meaning 90% of them had been missed before."

Implications for dark matter estimates?

[Anonymous Coward]

Anyone got any idea how this impacts our estimates of dark matter?

Does dark matter disappear or do we still need some hiding to explain things?

Seeing them all?

[Anonymous Coward]

If we only saw 10% of them before, how do we know we're seeing all of them this time?

Not "90% of the Universe"

[Neon Aardvark]

Merely 90% of the Visible Universe that we couldn't see before.

The Visible Universe probably constitutes a very small (perhaps even infinitesimally small) fraction of the actual physical Universe. The rest will, according to Relativity, always be hidden.

Re:Implications for dark matter estimates?

[WrongSizeGlass]

I think 90% of the dark matter just got a little brighter ... though I doubt they'll declare dark matter "a mistake" because so many in the astrophysics community have stood behind the concept.

MOD PARENT UP

[forand]

People are far too enamored with dark matter. It is extremely frustrating having to place everything in the context of dark matter (often with only the most tenuous connection) when trying to explain interesting observations to the general public. The author of this article, thankfully, made it clear at the top of the article that it was NOT related to dark matter and went on to explain the observation.

Re:90%, not so coincidentally...

[Neon Aardvark]

This has absolutely nothing do to with dark matter. So, yes it is a coincidence. And an approximation.

They're improving their technique for observing distant galaxies. Which doesn't in any way invalidate observations of (astronomically) very close galaxies. Which is what we base the existence of dark matter on.

Re:Next step: a better name

[spun]

That's what Zoolander would name it.

I was thinking Leonard of Quirm.

Re:Implications for dark matter estimates?

[Jeff Satterley]

The Bad Astronomy post talks about dark matter: [Note: before you ask, this has nothing to do with dark matter. See below!] I’ll note: this has nothing to do with dark matter. As it happens, 90% of the matter in the Universe is in a form that emits no light, but affects other matter through gravity. We know it exists, and you can find out why here [discovermagazine.com]. We know it exists locally, in nearby galaxies and clusters of galaxies, too. This new result doesn’t affect that, since the now un-hidden galaxies are very far away, like many billions of light years away. They can’t possibly affect nearby galaxies, so they don’t account for dark matter.

Re:Implications for dark matter estimates?

[Mr Thinly Sliced]

Very nice. Thank you for explaining a little about what evidence we have for dark matter.

I knew about the fudge factor we needed to get the equations to work - I didn't know we have actually seen something like that.

Re:MOD PARENT UP

[CaptainPatent]

Slashdot readers never bother reading the article.

fixed that for both of you.

Re:I Smell Another Apple Ad

[b4dc0d3r]

A quote from the summary, which should appear directly above the comments in case you are not familiar with slashdot, is:

and voila, ten times as many galaxies could be seen

.

X is the previous amount, and 10x as the new amount of galaxies.

So simple math gives you X + YX = 10X
X(1+Y)=10x
(1+Y)=10
Y=9

So we see a 10-fold total galaxies, which is 9-fold improvement. Or to put it another way, the new 100% is 10 times the previous amount, which must have been 10%, leaving 90% more.

You're reading it as "90% of the universe found", from the headline, which is an attempt, although a poor one, at conveying the increase in observable galaxies. It is correct if you assume that we found 90% of the now-current estimate of the number of galaxies, in other words insert the word "known" in the title somewhere. Choosing not to even read the summary has left you understandably confused, and I'm glad that I was able to help. At the same time, I'm concerned that the other replies did not draw your attention to this. But I was able to post an accurate reply while maintaining an air of disdain and condescension, so that makes me feel good about myself. Thank you for affording me the opportunity, and welcome aboard.

Re:Redshift?

[canadian_right]

Asking if professional astronomers took the red shift into account is like asking if some surgeons washed before performing surgery.

Re:Someone update the Drake Equation!

[thisisntme]

This does not affect the Drake equation at all. From Wikipedia:

The Drake equation [...] is an equation to organize our guesses about the potential number of extraterrestrial civilizations in our galaxy, the Milky Way.

been waiting for this

[SpinningCone]

I always thought that dark matter was a hack. "our numbers don't add up.. therefore 90% of the universe is a type of matter that has gravity but doesn't interact with the electromagnetic spectrum, or anything else, also there's none of it near earth, it's like the 90% that's far away." sounds good to me :-p