Universe's Dark Ages May Not Be Invisible After All 55
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.
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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...
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You mean cultural suicide. After all, it violates the freedom of religion, which is absolutely vital for the marketplace of ideas to exist. That marketplace is the essence of Western Culture, underlaying every currently reigning local ideas.
The only thing mosques do is give the local populace a chance to copy whatever good ideas Islam might have, and of course the other way around. And the only ones it threatens are those who are on top in current status quo and wis
matter, antimatter and everything else imaginable) (Score:2)
Negative matter?
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Turtles. Billions and billions of turtles.
And exactly one pony.
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Sometimes, like in the case of the Big Bang, there is no way to test it, so it will forever be speculation.
Testable predictions have been made, tested, and new ones continue to be made.
When a critical element of science, namely testing one's hypotheses is missing, it makes me very unwilling to consider what's being practiced as being "science".
Trying to pretend testing of hypothesis doesn't exist and rebranding something people don't like (e.g. dark matter), isn't practicing science either.
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There is a name for your complaint:
https://en.wikipedia.org/wiki/Duhem%E2%80%93Quine_thesis
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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
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Correction:
This is how we know the Sun is^W made^W of^W contains some Helium. (And what proportion.)
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Wonderfully written post. I just want to point out that the way you relate the history, it's tautological that the Sun contains helium. After all, we named the element after the observations of the Sun.
Starts with a Bang (Score:5, Insightful)
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hardly any Stuff that Matters
But we get Matter that Stuffs.
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There are so many of these crappy articles every day that I've just started ignoring anything that "starts with a bang".
It's such a shame what has become of slashdot lately.
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Shamefully, I actually read TFA. It has a lot of great background on the problem, and is a fine read for someone who hasn't ever looked into cosmology before, but it actually has less information than the Wikipedia article [wikipedia.org] on using the 21cm "hydrogen line" to observe the "dark age" of the universe. Prettier pictures than Wikipedia, though.
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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.
While i can't disagree with you (althrough i find this "Ask Ethan" to be good written, and deep enough, stuff), you must agree that this story is at least one of the rare Slashdot stories about something other than the usual TOTALY unrelated to "news for nerds" - in the one month i am a "Slashdoter" i managed to make so many comments about religion (i am a/the religious guy!) or the Greek economy (i am Greek!) for example, but only few about something related to nerds (but even then i did not felt so good:
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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.
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After all, it too has been in a James Bond movie.
Here's something to help you out, just look up Aricebo Observatory. It's probably the single most famous radio telescope/observatory in all of science. They've even done documentaries on it. Just look through the catalog of old NOVA episodes. Heck, there's even been research done on the positive impact it's had on the local wildlife by creating a rather interesting location where other human
Gold Medal attempt (Score:2, Funny)
The forbidden Hydrogen spin-flip-transition was first banned at the Olympic Games of 13,299,999,996 BC due to a string of injuries. It will be interesting to see if they can pull it off, although the judges may not be impressed by such an illegal maneuver, which will almost certainly result in an automatic disqualification. Still, they are choosing to make a statement of validity of the maneuver, even at the expense of a possible gold medal. Riveting. Simply riveting.
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In Soviet Russia ... (Score:2)
what? (Score:3)
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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.
Re:what? (Score:4, Informative)
And, if it helps, shorter wavelengths = higher frequency, if you choose to describe it that way (Since, the frequency in Hz of light, including radio, is the distance light travels in a second divided by the wavelength).
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Higher energy photons are distinct from lower energy photons in having a shorter wavelength. They both travel at (about) the same speed. Presumably in a true vacum they would travel at exactly the same speed.
Thus blue light is more energetic than red light, and has a shorter wave length. You measure the energy of the photons by absorbing a certain number and measuring the change in velocity or temperature of the thing that absorbed them. (Usually this is done by some sort of photocell arrangement were t
Re:what? (Score:4)
Blue light is higher energy than red light.
X-Rays are higher energy than any visible light.
Radio waves are lower energy than any visible light.
Gamma rays are higher energy than X-Rays (and all other photons, because past a point, we call everything a gamma ray)
http://en.wikipedia.org/wiki/E... [wikipedia.org]
If you had enough energy to make one 350nm photon (a wavelength that just might be visible, maybe, as it is UV), you could instead make two 700nm photons with the same energy (which also might just barely be visible, as it is at the edge of infrared). More reasonably, if you had enough energy to make 3 blue photons, you could instead make 4 red ones with that same amount of energy.
http://en.wikipedia.org/wiki/V... [wikipedia.org]
http://www.chemteam.info/Elect... [chemteam.info]