Universe's Dark Ages May Not Be Invisible After All

StartsWithABang writes: The Universe had two periods where light was abundant, separated by the cosmic dark ages. The first came at the moment of the hot Big Bang, as the Universe was flooded with (among the matter, antimatter and everything else imaginable) a sea of high-energy photons, including a large amount of visible light. As the Universe expanded and cooled, eventually the cosmic microwave background was emitted, leaving behind the barely visible, cooling photons. It took between 50 and 100 million years for the first stars to turn on, so in between these two epochs of the Universe being flooded with light, we had the dark ages. Yet the dark ages may not be totally invisible, as the forbidden spin-flip-transition of hydrogen may illuminate this time period after all.

Comments

Starts with a Bang

[vikingpower]

is not scientific news, nor does the link point to any academic results. "Ask Ethan" is simply a popular-scientific discussion of results already known. So no News for Nerds, and hardly any Stuff that Matters, IMHO.

Re:Starts with a Bang

[Required Snark]

You're absolutely right. Ever person who has read Slashdot since it started knows far more about astrophysics then that feeble Ethan guy. He's scientifically illiterate compared to the rest of us.

We all just woke up one morning and said to ourselves "I'm going over to Wikipedia and read about the forbidden spin flip transition of hydrogen and it's relationship to the 'dark age' period when the expanding universe first became transparent to electromagnetic radiation." I know I did.

You shouldn't hold back. Tell the full story. We all know at least as much as the authors of any author who is the subject of a Slashdot posting. Slashdot readers that that superior to everyone else.

Since we are all so damned smart and know so much about everything, the only logical conclusion is that Slashdot should just shut down. It's beneath us. I'm so glad you pointed this out to everyone here. Even given our collective genus, you are slightly superior. I take my hat off to you, sir.

Of course, there is a somewhat simpler solution that you could unilaterally execute that would solve the problem: never log into Slashdot ever again. It's an insult to those of true enlightenment and we should all immediately log off. Leave it to the cretins and let it die the natural death of the stupid. I'm taking your advice, and this is my last time here.

Arrogant much?

Re:Just wait, Islam will lead us to another one

[myowntrueself]

Islam is incompatible with Western Civilization - why are we tolerating it?

Banning Mosques is cultural self-defense.

Actually, intellectual property restrictions might be leading us more into a dark age...

Re:Is science this speculative actually science?

[Drumhellar]

No. We looked at the sun. Helium is something we can see, though, not with our eyes.

You see, beyond the basic blackbody radiation (Which is purely due to matter radiating heat), each atom glows at specific wavelengths - this happens when an electron moves to a lower energy state (Think: smaller orbit), and emits a photon at the energy level that corresponds to the difference. Every atom has its own set of wavelengths that it emits - this is called the emission spectrum, and if you stretch out the spectrum of a point of light, you can see bright spots that correspond to this emission spectrum.

Additionally, each atom has a set of wavelengths that it highly efficient at absorbing. These appear as darker spots when you spread out the spectrum of a star. These are called absorption spectrum, and they are unique to each element.
Analyzing the emission and absorption spectrum of the Sun showed that it was largely made up of a gas that hadn't been discovered, because there were strong emission and absorption lines that corresponded to an element we hadn't yet discovered. This gas was named "Helium", after the Greek word "Helios", meaning the sun.

A number of years later, knowing that there was strong evidence of its existence, chemists managed to isolate Helium in the lab, and ran tests on it to measure the properties of Helium's spectrum, and it matched to what we saw in the Sun.

This is how we know the Sun is made of Helium.

Re:what?

[Anonymous Coward]

You know that whole mass-equivalence equation Einstein is famous for? E=mc^2?

That's a simplification.The expanded version is called the Energy-momentum relation:

E^2 = (pc)^2 + (mc^2)^2

p is momentum. When momentum is 0, you can simplify to:

E = mc^2

If you have a massless particle, such as a photon, m = 0. That make the whole equation simplify to:

E = pc

Thus, high energy photons have high momentum.