So That's Where The Universe Was Hiding...

Post Reply
Sionnach Glic
4 Star Admiral
4 Star Admiral
Posts: 26014
Joined: Fri Jul 13, 2007 10:58 pm
Location: Poblacht na hÉireann, Baile Átha Cliath

So That's Where The Universe Was Hiding...

Post by Sionnach Glic »

This is fascinating news: 90% of the distant Universe was thought to be missing, but it was recently found. And what's weird is, it was found to be in the red. Quite literally.

First, a bit of background. Galaxies are filled with hydrogen gas, and that gas is a major component of the clouds that collapse to form stars. When that happens, the hot stars ionize the gas: the flood of ultraviolet light strips the electron away from the proton, freeing both. If the electron gets near the proton again, they can recombine. Because of quantum mechanics, the electron can only exists in certain energy states, which are a bit like steps in a staircase. You can jump from the third step down to the second, but there is no second-and-a-halfth step.

So it is with electrons. It used to be taught that this levels were like orbits, but that's not a great analogy; the staircase is better. So if the electron is on the second level and drops to the first, it gives off energy in the form of light (just like when you step down you lose a bit of energy too, and it takes energy to go up a step). For the 2 to 1 step in hydrogen, the photon emitted is in the ultraviolet, and has a special name: Lyman alpha.

Ionized hydrogen gas clouds tend to blast out lots of Lyman alpha. This makes it a good way to search for distant star forming regions; just look for that wonderful wavelength of light associated with the 2 - 1 transition of hydrogen.

As it happens, we know that when the Universe was young, about a quarter the age it is now, star formation was going on at a much higher rate on average than it does now. So astronomers figured, hey, why not do searches for distant galaxies using Lyman alpha? They should pump it out, and make them easy to see.

So they looked. And to their surprise, they only found about 10% of the galaxies they predicted they should!

Uh oh.

This has been a problem for some time. But it's not anymore: a recent experiment by astronomers shows that the galaxies are there, but they're hidden!

What they did is look in one part of the sky, using the GOODS South field (part of which is pictured above), trying to find Lyman alpha emitting galaxies. Then they looked at the same region, but looked instead for H alpha, the line emitted when an electron jumps down from the third energy level to the second. And guess what they found: tons of galaxies!

The problem, they surmised, is that the galaxies are actually there and emitting Lyman alpha. But before that ultraviolet light can get out of one of those galaxies, it gets reabsorbed by gas inside the galaxy itself. We never see it.

But H alpha can more easily escape the galaxies once it's produced. For one thing, it's red light, and that can penetrate the gas and dust better than the ultraviolet Lyman alpha light can. There are other more complicated reasons as well, but the point is, the galaxies were simply hidden from us before, but not anymore. By extrapolating their results, it looks like they found 90% of the distant Universe!

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. 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.

I love this study. It's a great application of simple logic, though it wasn't so simple to do: they had to use a lot of time on a monster 8 meter telescope to do it! But they were able to answer a question that has been around for some time, and it really does look like they've solved it.

And, as always, it makes me wonder what else is lurking out there in space, hidden but for a leap of logic and technology that will allow us to unveil it. Science is all about thinking around problems, and peeking into dusty corners. Sometimes the most interesting things are found there including, in this case, the vast majority of the Universe!
Very interesting.
"You've all been selected for this mission because you each have a special skill. Professor Hawking, John Leslie, Phil Neville, the Wu-Tang Clan, Usher, the Sugar Puffs Monster and Daniel Day-Lewis! Welcome to Operation MindFuck!"
Mikey
Fleet Admiral
Fleet Admiral
Posts: 35635
Joined: Fri Jul 27, 2007 3:04 am
Commendations: The Daystrom Award
Location: down the shore, New Jersey, USA
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Mikey »

Dammit, now I have to go find a new hiding place.
I can't stand nothing dull
I got the high gloss luster
I'll massacre your ass as fast
as Bull offed Custer
Aaron
3 Star Admiral
3 Star Admiral
Posts: 10988
Joined: Thu Aug 23, 2007 10:01 pm
Location: Timepire Mobile Command Centre
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Aaron »

Better add a few dozen more feet to my bunker....*sigh*
Tsukiyumi
4 Star Admiral
4 Star Admiral
Posts: 21747
Joined: Fri Oct 12, 2007 2:38 pm
Location: Forward Torpedo Tube Twenty. Help!
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Tsukiyumi »

:lol:
There is only one way of avoiding the war – that is the overthrow of this society. However, as we are too weak for this task, the war is inevitable. -L. Trotsky, 1939
Aaron
3 Star Admiral
3 Star Admiral
Posts: 10988
Joined: Thu Aug 23, 2007 10:01 pm
Location: Timepire Mobile Command Centre
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Aaron »

I swear, if I ever win the lotto I'm building a full on WWI style trench system and bunker complex in my backyard.
Mark
4 Star Admiral
4 Star Admiral
Posts: 17671
Joined: Fri Jul 18, 2008 12:49 am
Location: Honolulu, Hawaii

Re: So That's Where The Universe Was Hiding...

Post by Mark »

Better stock up on ammo and twinkies........for the upcoming invasion.
They say that in the Army,
the women are mighty fine.
They look like Phyllis Diller,
and walk like Frankenstein.
User avatar
Laughing Man
Ensign
Ensign
Posts: 116
Joined: Sat Dec 05, 2009 11:37 am

Re: So That's Where The Universe Was Hiding...

Post by Laughing Man »

And i thought it was revolving around me!

Well at least the sun still shines out of . . .
Heck Is Where People Go Who Don't Believe In Golly!
Aaron
3 Star Admiral
3 Star Admiral
Posts: 10988
Joined: Thu Aug 23, 2007 10:01 pm
Location: Timepire Mobile Command Centre
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Aaron »

Mark wrote:Better stock up on ammo and twinkies........for the upcoming invasion.
Good plan, I'd hate to have to survive on just my stockpile of baked beans.
Mikey
Fleet Admiral
Fleet Admiral
Posts: 35635
Joined: Fri Jul 27, 2007 3:04 am
Commendations: The Daystrom Award
Location: down the shore, New Jersey, USA
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Mikey »

Cpl Kendall wrote:Good plan, I'd hate to have to survive on just my stockpile of baked beans.
Well, at least that would alleviate the need for fuel for heating.
I can't stand nothing dull
I got the high gloss luster
I'll massacre your ass as fast
as Bull offed Custer
User avatar
Lighthawk
Rear Admiral
Rear Admiral
Posts: 4632
Joined: Fri May 22, 2009 7:55 pm
Location: Missouri, USA, North America, Earth, Sol System, Orion Arm, Milkyway Galaxy, Local Group, Universe

Re: So That's Where The Universe Was Hiding...

Post by Lighthawk »

Cpl Kendall wrote:I swear, if I ever win the lotto I'm building a full on WWI style trench system and bunker complex in my backyard.
You mean you don't have one already? Sheesh, when the zombie apocalypse starts, you'll be one of the first to join the ranks of the undead.
Image
Aaron
3 Star Admiral
3 Star Admiral
Posts: 10988
Joined: Thu Aug 23, 2007 10:01 pm
Location: Timepire Mobile Command Centre
Contact:

Re: So That's Where The Universe Was Hiding...

Post by Aaron »

I have a rifle, a spear and explosives. I think I'll be fine for the hour drive to the base and the training area bunker. ;)
RK_Striker_JK_5
3 Star Admiral
3 Star Admiral
Posts: 12986
Joined: Wed Jul 25, 2007 5:27 am
Commendations: The Daystrom Award, Cochrane Medal of Excellence
Location: New Hampshire
Contact:

Re: So That's Where The Universe Was Hiding...

Post by RK_Striker_JK_5 »

Bah, I can outrun the zombies. :P
User avatar
Lighthawk
Rear Admiral
Rear Admiral
Posts: 4632
Joined: Fri May 22, 2009 7:55 pm
Location: Missouri, USA, North America, Earth, Sol System, Orion Arm, Milkyway Galaxy, Local Group, Universe

Re: So That's Where The Universe Was Hiding...

Post by Lighthawk »

RK_Striker_JK_5 wrote:Bah, I can outrun the zombies. :P
Not the modern day crop you can't. They don't shuffle, they sprint, and they don't feel fatigue or pain.
Cpl Kendall wrote:I have a rifle, a spear and explosives. I think I'll be fine for the hour drive to the base and the training area bunker. ;)
Good luck
Image
Post Reply