What Happens To All the Universe's Hydrogen?

StartsWithABang (3485481) writes "Just a second after the Big Bang, the Universe was a hot bath of radiation, with a small fraction of protons and neutrons in about equal numbers left over. By time it was four minutes old, it was 92% hydrogen (by number of atoms) and 8% helium. Yet the Universe has aged nearly 14 billion years since then, and have formed many generations of stars, all of which burn hydrogen into heavier elements. So how much hydrogen is left, and how much will be left far into the future? A lot more than you might think."

Comments

And what about dark matter?

[1 a bee]

I'm a bit skeptical of such cosmological estimates. If there is more dark matter in the universe than ordinary matter (by a factor of 4:1 they say), wouldn't you expect it to somehow figure in the "calculations" going back to the big bang? I saw no mention of it in the article. In fact, come to think of it, you seldom hear much about that big elephant dark matter in the room in the first minutes after the bing bag.

Love reading about cosmology, but I think readers should be warned this is a very speculative field of study. Ideas and models in vogue today will likely not be in a few decades. I'm reminded of my physics professor of many years ago who claimed "Cosmology is as mature as botany was before Darwin."

Re:And what about dark matter?

[meta-monkey]

The problem with the new Cosmos is not all the "facts" they present are scientific. They also deal with history, and some of their "facts" are misleading or downright wrong, and we don't apply the scientific method to history.

I get that Seth MacFarlane is an atheist and wants to push his creed (or lack thereof) on people. But in the first episode of Cosmos, the whole story about Bruno and his persecution was just wrong. Yes, Bruno did have an idea that the universe was infinite and that the sun was just another star. But he was not a scientist, did not apply the scientific method and did not back up his ideas with experiment or observation. He was "right" in the same way a broken clock is right twice a day. He was a mystic who wrote books about magic and thought the stars and planets had souls. While no one should be burned at the stake for any reason, he was not killed because of his scientific views, he was burned because of his religious heresies like denying the divinity of Christ. The bit went on for about 8 minutes of airtime, in a 40 minute show. They spent 20% of a science show talking about the persecution of a religious man for his religious views but making it out as if he were persecuted for his scientific practice, when he wasn't. It was purely a shot at religion in general and the Catholic Church in particular in order to push MacFarlane's world view. I thought they sacrificed their credibility by intentionally misleading people about historical facts.

When my kid is old enough to understand Cosmos, I'll be showing him Sagan's version. Little has changed with regards to the history of science since the original Cosmos and now, and Carl wasn't pushing an agenda. He was just giving you facts. Also, CGI not withstanding, I thought the production values of the original were better. I like the way they hired actors to portray famous moments in science rather than Neil's version with cartoons to depict past events.

Re:I was wondering this myself...

[Sockatume]

You don't burn hydrogen in a hydrogen vehicle. You use it to run a fuel cell which, being electrochemical, doesn't have the Carnot limit on its efficiency. So even a relatively inefficient hydrogen cycle can actually be better than making liquid fuels for an internal combustion engine. The challenge, as you say, is engineering a good hydrogen storage material. (The chemistry problems involved in the efficient photolysis of water are related to the ones involved in the efficient photocatalytic production of liquid fuels, so the research on each side tends to assist the other.)

On the gripping hand, fast-fuelling long-range vehicles are an artefact of cheap, readily available gasoline rather than an inherent part of the human condition so I can't see them being competitive with modest-range battery vehicles in the long term.