helium

Why did the Universe start off with Hydrogen, Helium, and not much else?

esiegel — Fri, 05 Jul 2013 13:11:45 +0000

Why did the Universe start off with Hydrogen, Helium, and not much else?

"I see a lot of new faces. But, you know the old saying, 'out with the old, in with the nucleus.'" -The Simpsons

Looking around the Universe today, there's no doubt that there's plenty of hydrogen and helium around; after all, it's the nuclear fusion of hydrogen into helium that powers the vast majority of stars illuminating the entire cosmos!

Image credit: ESA/Hubble, NASA and H. Ebeling.

But here on Earth, hydrogen and helium are only a small part of the world we inhabit. By mass, hydrogen and helium combined make up far less than 1% of the Earth, and even if we restrict ourselves to the Earth's crust, it's still just a tiny percentage compared to the other, heavier elements.

Image credit: Gordon B. Haxel, Sara Boore, and Susan Mayfield from USGS / Wikimedia user michbich.

Practically all of these heavy elements were formed in generations of stars: stars that lived, burned their fuel into heavier elements, died and shed their heavy, enriched elements back into the cosmos, and were incorporated into the next generations of stars and -- when the heavier elements became abundant enough -- rocky planets.

Image credit: NASA / Lynette Cook.

But the Universe didn't start off with these heavier elements at all. In fact, if you'll remember what the Big Bang says, the Universe is expanding (and cooling) now, meaning that all the matter in it was closer together -- and the radiation in it was hotter -- in the past. If you go back to a sufficiently early time, you'll find that the density was high enough and the temperature was hot enough that you couldn't even form neutral atoms without them immediately being blasted apart! When the Universe cooled through that phase, that's when neutral atoms formed for the first time, and where the cosmic microwave background comes from.

Image credit: Pearson / Addison Wesley, retrieved from Jill Bechtold.

At that time, the Universe was made out of about 92% hydrogen atoms and 8% helium atoms by number (or about 75-76% hydrogen and 24-25% helium by mass), with trace amounts of lithium and beryllium, but not much else. But you might wonder how it got to have exactly that ratio? After all, it didn't have to be that way; if the Universe was hot and dense enough to undergo nuclear fusion early on, why did it only fuse atoms up to helium, and why didn't more of the Universe become helium than it did?

To find the answer, we need to go way back in time. Not just to the first few hundred thousand years of the Universe, when it was making the first atoms, nor even to the first years, days, or hours. No, we need to go back to when the temperatures were so high, when the Universe was so hot, that not only could atomic nuclei not form (for they'd be immediately be blasted apart), but to a time when the Universe was so hot that the Universe was filled with nearly equal amount of matter-and-antimatter, when it was just a fraction of a second old!

Image credit: James Schombert of the University of Oregon.

It was once so hot that the Universe was filled with nearly equal amount of matter and antimatter: protons and antiprotons, neutrons and antineutrons, electrons and positrons, neutrinos and antineutrinos, and of course photons (which are their own antiparticle), among others. (They're not exactly equal; see here for more on that.) When the Universe is hot -- and by hot, I mean above the temperature needed to spontaneously create a matter/antimatter pair from two typical photons -- you get huge amounts of that form of matter and antimatter. They get spontaneously created from photons just as quickly as they find one another and annihilate back into photons. But as the Universe cools, those matter/antimatter pairs begin to annihilate faster, and it becomes more difficult to find photons energetic enough to make them. Eventually, it cools enough that all the exotic particles go away, and all the antiprotons and antineutrons annihilate with protons and neutrons, leaving only a small asymmetry of matter (in the form of protons and neutrons) over antimatter, bathed in a sea of radiation.

Image credit: me, background by Christoph Schaefer.

At this point, when the Universe is a fraction of a second old, there are roughly equal amounts of protons and neutrons: about a 50/50 split. These protons and neutrons will eventually become the atoms in our Universe, but they've got a lot to go through first. On the other hand, electrons (and positrons) are much lighter, so they still exist in huge numbers (and at great energies) for a while longer.

Image credit: Addison-Wesley, retrieved from J. Imamura / U. of Oregon.

It's still hot enough that protons and neutrons can convert into one another very easily: a proton can combine with an electron to make a neutron and (an electron) neutrino, while a neutron can combine with (an electron) neutrino to make a proton and an electron. While there aren't that many protons and neutrons in the Universe at this time, electrons and neutrinos outnumber them by around a billion-to-one. This is why, early on, there's about a 50/50 split of protons and neutrons.

Neutrons, as you'll remember, are slightly heavier than protons: by about 0.2%. As the Universe cools (and the excess positrons annihilate away), it becomes rarer and rarer to find a proton-electron pair with enough energy to create a neutron, while it's still relatively easy for a neutron-neutrino pair to create a proton-electron pair. This converts a substantial fraction of neutrons into protons during the first one-to-three seconds of the Universe. By time these interactions have become insignificant, the proton-to-neutron ratio has changed from about 50/50 to 85/15!

Image credit: Smith, Christel J. et al. Phys.Rev. D81 (2010) 065027.

Now, these protons and neutrons are abundant, hot, and dense enough that they can fuse together into heavier elements, and believe me, they'd love to. But photons -- particles of radiation -- outnumber protons-and-neutrons by more than a billion to one, so for minutes of the Universe expanding and cooling, it's still energetic enough that every time a proton and neutron fuse together to form deuterium, the first stepping-stone in nuclear fusion, a high-enough energy photon immediately comes along and blasts them apart! This is known as the deuterium bottleneck, as deuterium is relatively fragile, and its fragility prevents further nuclear reactions from occurring.

Image credit: me, modified from Lawrence Berkeley Labs.

In the meantime, while the minutes tick by, something else is going on. A free proton is stable, so nothing happens to them, but a free neutron is unstable; it will decay into a proton, electron, and an (electron) antineutrino with a half-life of about ten minutes. By time the Universe has cooled enough that the created deuterium wouldn't be immediately be blasted back apart, more than three minutes have gone by, further changing the 85%-proton/15%-neutron split to nearly 88% protons and just a hair over 12% neutrons.

Image credit: Ronaldo E. de Souza.

Finally, with deuterium forming, nuclear fusion can proceed, and it proceeds extremely rapidly! Through a couple of different fusion chains, the Universe is still hot and dense enough that pretty much every neutron around wind up combining with one other neutron and two protons to form helium-4, an isotope of helium that's much more energetically stable than deuterium, tritium, or helium-3!

Images taken from LBL, stitched together by me.

By time this happens, though, the Universe is nearly four minutes old, and is far too diffuse and cold to undergo the next major step of fusion that happens in stars, which is to fuse three helium-4 atoms into carbon-12; that process will have to wait tens of millions of years until the Universe's first stars form!

But these nuclei are stable, and there will also be a trace amount of helium-3 (which tritium will also decay into, eventually), deuterium (hydrogen-2), and very small amounts of lithium (and probably even smaller amounts of beryllium) formed by very rare fusion reactions.

Image credit: NASA, WMAP Science Team and Gary Steigman.

But the overwhelming majority of neutrons -- 99.9%+ of them -- wind up locked up in helium-4 nuclei. If the matter in the Universe contained just a hair over 12% neutrons and just a hair under 88% protons just prior to nucleosynthesis (the fusion into heavier elements), that means that all of those neutrons and and equal amount (just over 12% of the Universe) of protons winds up becoming helium-4: a total of 24-to-25% of the mass, leaving 75-to-76% of the Universe as protons, or hydrogen nuclei.

Image credit: Ned Wright, via his excellent Cosmology tutorial at UCLA.

So that's why, by mass, we say 75-76% was hydrogen and 24-25% was helium. But each helium nucleus is around four times the mass of a hydrogen nucleus, which means that, by number of atoms, the Universe is around 92% hydrogen and 8% helium.

This primordial, unprocessed material has actually been detected observationally, and is one of the three cornerstones of the Big Bang, along with Hubble expansion and the cosmic microwave background. And that's where all the elements in the Universe started from! Everything you are, everything you know, and every material object you've ever interacted with came from this primordial sea of protons and neutrons, and was once a mere collections of hydrogen and helium atoms. And then the Universe happened...

Image credit: NASA / JPL-Caltech / Spitzer / IRAC / N. Flagley and the MIPSGAL team.

and here it all is! And that's where -- if you go way, way back -- all the atoms came from.

esiegel Fri, 07/05/2013 - 09:11

Tags

Big Bang

Physics

abundance

Fusion

Yet another nice article. I like the way the illustrations break up the text and make it easy reading.

Something that doesn't feature in the standard description is that you can "melt" hadrons in a "quark-gluon plasma", see http://physicsworld.com/cws/article/print/2009/sep/01/of-gluons-atoms-a…. I think this might turn out to be important for baryon and lepton asymmetry myself, wherein positrons are actually more like protons than electrons are. That's another one for another day!

Rad! I'm always curious as to why and how there was "small amounts of lithium" in the very early stages on the universe, but I think I grok the random fusion chain now. If it is something else, please tell me.

Also, Ethan, relevant to this post: a friend and very talented musician/artist Kim Boekbinder AKA The Impossible Girl just released a new space-themed album, called "The Sky is Calling"!!

Youtube for the first music video from the album, for the song "Stellar Alchemist" here: http://www.youtube.com/watch?v=ENJKo5jqjUw&feature=youtu.be
You and readers will appreciate it I'm sure.

Excuse me for thinking, but what if time is more than a marker of passage, what if it is the fundamental particle, intertwined with space, what if it is time that exploded creating the big bang? Excuse me for thinking.

You will need to actually specify what the hell you're on about, Tony. Because what you wrote just there was meaningless garbage.

What if you reversed the osmosis of the dilithium crystals and injected red matter to cause a time skip in a bagel?

xcuse my garbage.

No.

Wow, what is your definition of time. Why does time slow down near a large mass such as a black hole, why does time stop at the speed of light, the twins scenario. Why should time vary at all. It does, but why? What is time? Explain it to me. Why is the arrow of time what it is? I know you must know, not just speculation.

wow, If time stopped so would the universe instantly disappear. The Universe and time began at the same instant, so, maybe time is a something, maybe it's the power behind inflation. the basic wave function of all functions, that permeates all of space and matter. When people have experience NDE they say that time essentially stopped they couldn't tell if they had been gone for a second or a much longer time, so if this is true than time is a property of this universe alone, barring other universes that may exist, and this is also essentially speculation by Physicists, though I believe this may well be. So, science begins with imagination, and a desire to know.

When people have experience NDE

they are experiencing a chemical imbalance in the brain, nothing more - certainly nothing indicative of any deep notions about the universe.

Everyone experiences an NDE.

It's called "life".

"If time stopped so would the universe instantly disappear."

If time stopped, how is there an instant for something to disappear in?

The ancient Greeks had this problem, Zeno's paradox it is called.

Most people know of it but know that it is a fallacious reasoning problem, even if they don't know why.

You're still at the "Well, how DOES the arrow catch up to the tortoise?!?!".

"Why does time slow down near a large mass such as a black hole"

It doesn't. For the thing in that situation, time moves just as fast as it always did.

Maybe Ethan can explain this at some time.

wow, time does dilate relative to other objects who are not near the massive object.

Tony Rotz: You're confusing the physics notion of subjective time -- the relative timing of events may differ for different observers -- with the psychological notion of time perception. This is what your brain does, creating a cohesive narrative and giving you a sense of how much time passes. And just like everything else our brain does on our behalf, this involves a lot of fudging, filling in blanks, and outright lies.

There have been experiments done on NDEs and the perception that time slows down. While people in the experiments claimed that time slowed down and they could see everything in complete detail, their measured ability to recall those details correctly was no better than normal. Events that occurred too quickly to be perceived normally were also not perceived during the experiment.

In short, it truly is only the *perception* of time that changes. Not actual time, and not any other form of perception. The brain just fills in a bunch of details because it decided that event took much longer than it really did, and therefore you should have been able to see a lot more than you normally would. So what you get is a seemingly self-consistent picture (cus that's what your brain does) that falls apart when put to the test.

Gleaning physical insight from this psychological quirk is like believing that the moving-image optical illusions Ethan posted a week or two back means the images are REALLY moving.

Oh and by the way this is expected -- as Wow hinted, the changes in time are only visible *relative* to something else. No matter how "fast" or "slow" time is going relative to somewhere else, you will always observe time locally to be going at the same rate (think about it).

The chance of you comprehending a response is zero, Tony.

wow, why don't you use your real name, if your going to insult someone instead of hiding behind a wow. What's wrong with you? This blog shouldn't be used for insults, grow up. Your hatred is showing.

I'll stay off this blog rather than cause your hatred to grow. good bye.

Uh, what the hell? No hate, dude, just completely sick and tired of meaningless drivel.

Tony, why do I have to use my real name? It is no more me than my pseudonym. Giving it to you will give you no more info than a fake one and you can find nothing else out about me from it.

If someone measures 50 grams 20 times, they still get 1Kg even if the mass of a standard kilogram changes. If the yardstick is half as long, but everything around it is also half as long... This is why it's called relativity. ;)

It's a scaling problem. Does that explain it? This is related to the term 'dimensionless constants'. Like if the universe octupled in volume but the reactions as related to the size of an object stayed the same, we would not be able to tell that everything became twice as far away. For extra fun, read up on something called 'doubly special relativity' and all the issues involved in a maximum frequency/velocity/density and Planck units. It's not like we can actually test to see what happens when a photon has a wavelength approaching the Planck length unit. It would take more energy than we can even imagine being applied by human technology.

@Helyx, great lyrics and videoclip indeed. I already bookmarked it :)

Anyway, I made a Dutch translation of this article:

http://www.astroblogs.nl/2013/07/15/nucleosynthese-en-de-oerknal/

love the pics on this web page excuse me for being a geek but its awesome.

SCIANCE RULES!!!!!!!!!!!!!!!

everything is fine but you unlike every other major site in the world has missed the most important point, how did protons, neutrons, electrons, quarks came into existence FROM NOTHING? the big bang was just a massive explosion that only had light, where did all these constituents come from?

There's a thread for that

http://scienceblogs.com/startswithabang/2011/02/02/can-you-get-somethin…

odd that you complained well after that thread was started about how no site had such a thread...

So the question is: if a site had such a conversation, would you ever have bothered to read it?

I think the answer is an emphatic "no".

Every going day, the number of thinking brains is increasing; this is pushing us (humans) of understanding more and more. Now a days, more than 6 billion thinking brains making a strong power to explore whether by NASA rockets or even by seating, drinking a cup of tea, thinking scientifically in it.
Human found that it’s a rounding ball, not a flat earth, visited the moon, well, voyjar has did a good job far away of home, in the same time scientists are working home making diamond in the labs,
The point I'm trying to clear is that everyone has the rights to think and to share, not has the rights only but HAS TO THINK AND SHARE, so please respect everyone's point.
Wish you all the best, hamed from Saudi hamedalshahrani@yahoo.com

Wow...Wow, it's people like you that slow down the progress of humanity. Just reading the comments above between you and Tony was the most frustrating aspect of my day. What do you get out of being so arrogantly pompous? I agree, what Tony was saying may not align with what science currently tells us, but it's an interesting thought and you attack it as if you know all the answers to the universe. Who knows what we might discover in another 100 years - the way we understand and interpret the universe is constantly changing as we discover more incredible things. I'm not saying your argument was invalid or incorrect, you seem to be very intelligent; I'm just saying that it makes you look incredibly weak by instantly shutting down a fellow thinker who is just trying to have an intellectual "outside of the box" conversation.

I'm sure you will respond with some sort of arrogant remark - well so be it - it was just hard to read this thread without trying to teach you a little bit of decency.

John Schmit, that is well said. I had the exact same reaction from reading this thread.

If the universe is expanding why the earth's distance to the sun is still the same? If the universe started from nothing or from tiny particle how did it grow?

@mario de vera #35: Because (1) the Earth and Sun are bound together gravitationally, and (2) the expansion rate is so tiny as to be unmeasurable on Solar System scales!

The expansion rate, today, is 67 km/s per megaparsec. That is, two galaxies one megaparsec apart would be separating at 67 km/s. Two galaxies ten megaparsecs apart would be separating at 670 km/s. And so on.

The Earth and Sun are 150 million km apart (on average). That's five TRILLIONTHS of a megaparsec (4.86e-12 Mpc). So the cosmic expansion is trying to separate the Earth and Sun at a rate of 0.32 billionths of a km/s (0.32 microns/second). The Sun's gravity is such that escape velocity at the position of Earth's orbit is 30 km/s, or ten billion times faster than the cosmic expansion rate. To paraphrase an old song, "Gravity, gravity will keep us together..."

It isn't just Wow's comments to Tony, but also to Big Sooka, that make me agree with IMHO and John's sentiments re pompous arrogance. The amusing thing is that Wow is hiding behind the theories we accept today that have been cleverly woven together by others, not by Wow. Judging from the attitude to others, I wouldn't even suggest Wow is intelligent. All that has come from Wow's input here is regurgitation gleaned by memorising detail. Not even one attempt at an imaginative original thought. Like what initiates particle/antiparticle creation? Why is the speed of light limited ? Is the cosmological principle valid ? Hide behind the shoulders of giants then, Wow.

@ian b #37: Wow has an excruciatingly harsh response to non-scientific comments. However, his responses are quite on target technically. If you are having a _scientific_ discussion, then you are best served by sticking with known science.

If you want to have an idly speculative discussion, then by all means wander off into non-scientific speculations.

Smart people, Stupid questions... (Not to offend anyone, we all have stupid questions.)

If the universe started from a single point, and that it is expanding, how is it possible for two galaxies to collide (eg: milky way and andromeda collision)?

Because space is moving, but the things are moving in that space.

Hi
You write:"By time this happens, though, the Universe is nearly four minutes old, and is far too diffuse and cold to undergo the next major step of fusion that happens in stars, which is to fuse three helium-4 atoms into carbon-12; that process will have to wait tens of millions of years until the Universe’s first stars form!"

I present my hypothesis: carbon production :)
7Li(p,y)8Be*(a,y)12C*
Link:https://scontent-vie1-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/12243382_108…
Lithium-proton reaction channels:
Link:https://scontent-vie1-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/12310578_109…
This hypothesis explains: 2H, 6Li, 7Be, n, Nucleosynthesis.
Regards nyemi

Write it up and present to a peer reviewed paper where your ideas will be discussed and viewed by those able to critique it without them worrying about wasting time on a crank site or vanity blog. When it gets past peer review, let us know.

Ok :).
Thank you, your reply.
Physics: "that which is not forbidden is mandatory".

Regards nyemi

Why on earth do you claim that? Obviously, the answers you got did not manage to make any impression on your knowledge.

That which is not forbidden is possible.

Regards, the genus homo sapiens sapiens.

Link:http://arxiv.org/abs/1602.07298

Yeah, still says fuck all about how you come to the assertion "that which is not forbidden is mandatory”.

Quite why you think it was relevant is probably from the same lack of intelligence as caused the claim in the first place.

Perhaps someone here can help me, because it is an extremely arduous task to find the answer on Google.

Stars fuse hydrogen into etc. etc. and dies once most of its hydrogen is depleted. Some stars supernova, thereby creating a nebula. More stars are born from this and the whole process starts over.

My question is, since most of the hydrogen was fused in the first star, where does all the hydrogen come from to fuel the next generation of stars?

Any help would be appreciated.

a supernova does not necessarily create new stars unless it is in a giant nebula itself, like the eagle nebula, in which case it is just adding to the elements in the cloud, a lone star like ours that supernovas just blows its cloud into space, like the crab nebula

@Andre #51: What you described for a star's lifetime applies fairly well to the Sun and other light-weight stars. The heaviest stars, the ones which produce supernovae and heavy elements, don't burn "most of [their] hydrogen." Rather, what we believe happens is that in their dense cores the hydrogen all burns to helium, then to carbon and oxygen, then to silicon, and so on up to iron. Since the temperature and pressure both get lower as you move out from the core, what we expect is that there will be "layers" (probably somewhat mixed) where different kinds of fusion are occurring. The outer envelope of the star (with a significant part of the star's mass) is likely to still be mostly hydrogen by the time the star explodes.

At the same time, when a supernova does happen and spreads heavy elements out into the nearby environment, that material is going to be mixed together with the mostly hydrogen and helium which is already there.

"75-76% of the Universe is hydrogen, 24-25% is helium." 101%?! What about the other elements?

Usually, this is explained as this Universe is ~74% hydrogen, ~24% helium, and ~2% all the other elements.

“75-76% of the Universe is hydrogen, 24-25% is helium.” 101%?! What about the other elements?

You've modified the text. It would be best to go back to the beginning and note the words "at that time."

Why the World Will Run Out of Helium

esiegel — Wed, 12 Dec 2012 17:30:07 +0000

Why the World Will Run Out of Helium

"I have this one little saying, when things get too heavy just call me helium, the lightest known gas to man." -Jimi Hendrix

Hendrix, as I told you once before, was almost right. We know of helium, conventionally, as the lighter-than-air gas that we fill balloons, blimps and zeppelins with in order to quickly and easily "defy gravity" here on Earth.

Image credit: Jonathan Trappe.

At least defying gravity is what it appears to do. But what's really going on is that helium is simply a very low-density gas. Our atmosphere, a mix of mostly Nitrogen (N₂) and Oxygen (O₂) gases, has an average molecular weight of 29. With a molecular weight of four, Helium is bested only by pure Hydrogen (H₂) gas (with a molecular weight of 2) in the low-density department.

And just as a stone sinks in the ocean or olive oil floats atop a glass of water, the principle of buoyancy ensures that the least dense materials will eventually -- once the effects of mixing are negligible (which they are, for atmospheric gases, over long enough times) -- find themselves layered atop the progressively more dense materials.

Image credit: Retrieved from Ms J's Chemistry Class.

This is true for solids (such as in the interior of the Earth, where the core is denser than the mantle, which is denser than the crust, which is denser than the oceans and so on), liquids (as shown above), and gases as well. For a gas giant like Jupiter, because it's so massive (many hundreds of times the mass of Earth), it's gravitational well is tremendous, and even the lightest of its atmospheric gases stay bound to the planet itself. On the other extreme end, the Moon and asteroids are far too low in mass to hold on to any of their atmospheric gases, and even the heaviest gas will be expelled from the planet thanks to the intense radiation coming from our Sun.

Image credit: retrieved from http://clowder.net/hop/railroad/asteroids.html.

The Earth's atmosphere is today mostly composed of Nitrogen (78%), Oxygen (21%), with trace amounts of other gases. However, if we could go back to when the Solar System was first forming, we'd discover that every planet would have had an atmosphere loaded up with the two most common elements in the Universe: Hydrogen and Helium.

Image credit: NASA.

The vast majority of the Hydrogen and Helium would have been confined to the Earth's atmosphere, and quickly would have risen to the uppermost layers. Other atoms -- Carbon, Nitrogen, and Oxygen -- would have bonded with Hydrogen (which is reactive) and not with Helium (which isn't) to produce methane, ammonia and water/water vapor. While the pure hydrogen gas and the helium would have been kicked off the planet relatively quickly by the Sun, the remaining gases would have stuck around for much longer, eventually leaving behind only the heaviest components of our atmosphere.

Image credit: G. H. Rieke of University of Arizona, originally from DHS international.

Now, it's no problem to "make" hydrogen, we've got oceans full of material that's 2/3 hydrogen. But what about Helium?

From the birth of the Solar System, there's practically no Helium left on Earth. (To be more precise, Helium composes 0.00052% of the Earth's atmosphere by volume.) But there is plenty of Helium here on Earth, and it has nothing to do with Helium anyplace else in the rest of the Universe.

Image credit: Rich Olson of http://nothinglabs.blogspot.com/.

These are some radioactive samples of Uranium and Thorium, two of the rarest elements found in nature. The most common isotopes -- Uranium-238 and Thorium-232 -- are radioactive, and will undergo a decay chain over timescales of billions of years.

Billions of years. In other words, a timescale comparable to the age of the Earth. Elements with much shorter lifetimes have all decayed away; that's why Uranium (or maybe Plutonium) is the heaviest naturally occurring element here on Earth; while many others were certainly around immediately following the supernova explosion that triggered the formation of our Solar System, everything with shorter lifetimes is completely gone by now. But when Uranium-238 and Thorium-232 decay, they do so in a very particular and important fashion.

Image credit: Nuclear Physics Laboratory, University of Cyprus.

They undergo a process known as alpha decay, where heavy elements emit an alpha particle, eventually leading to the creation of a more stable nucleus. But the "alpha particle" is actually the nucleus of a Helium atom! It will very quickly (in a matter of microseconds) pick up a couple of electrons and become a neutral helium atom, and since Helium atoms don't react with anything, all they'll do is attempt to rise up to the top of the atmosphere.

Which they can only do if they can find the atmosphere! Most of the Uranium and Thorium in the world exists deep underground, so wherever there's a Uranium or Thorium deposit in the Earth's crust that's been there for a long time (like, hundreds of millions of years), you're bound to find a large deposit of Helium gas, too. Luckily (perhaps) for Earth, the largest one in the world sits squarely underground near the middle of the United States.

Image credit: Helium Plants & Pipelines (Bureau of Land Management).

But we don't replenish this Helium! We mine it, but once we mine what's there, it will take either hundreds of millions of years to make more, or we need to find a new source of Helium, such as through mastering terrestrial nuclear fusion or perhaps mining the Moon.

In the meantime, we should be aware that every time we fill a Helium balloon, we're taking something that it took the entire natural history of the Earth to create and basically banishing it from our planet.

Image credit: Let's Party Ltd.

Helium is a rare and unique element, with some amazing scientific properties. It doesn't become a liquid until it's cooled to a temperature of 4 Kelvin, and it becomes a superfluid with some fantastic, frictionless properties when it's maybe half that temperature.

Helium is also used to supercool the world's most powerful particle accelerators (such as the LHC), and is instrumental in the creation of the most powerful magnetic fields ever achieved on Earth.

As long as we don't conserve and recycle our Helium, we are dooming mankind to a future shortage of Helium, and each balloon we fill with it (or inhale, for you teenagers) means that much less Helium for future generations here on Earth. We only discovered this element less than 150 years ago, and the U.S. National Helium Reserve is expected to be empty by 2018, with the remainder of the Helium supply completely privatized.

I'm not here to scare you into not using Helium balloons or to convince you that we need government regulation of Helium production or consumption; I'm simply telling you where Helium comes from, and why we're going to run out of it if we keep doing things the way we're doing them. I've done my part by telling you the science behind our Helium; the rest is up to you.

esiegel Wed, 12/12/2012 - 12:30

Tags

This is crazy! I had no idea we were using up our helium reserves... why does the human race overall not concern themselves with our mass consumption problem?

I read things about helium and how the price is way out of whack to where it should be. In other words, ridiculously expensive. The question is, why isn't it? Heck, I have a small tank in my basement I bought for a party for twenty bucks. I guess I'll save it til 2018, then eBay!

And just as a stone sinks in the ocean or olive oil floats atop a glass of water, the principle of buoyancy ensures that the least dense materials will eventually — once the effects of mixing are negligible (which they are, for atmospheric gases, over long enough times) — find themselves layered atop the progressively more dense materials.

So, how did an unreactive gas like CFC, 4+ times heavier than air, manage to get up high enough into the upper atmosphere in the 1990s to create the scarifying ozone layer holes in the polar regions?

Alan

1: CFCs are a catalyst. That means it is still there to do its thing again

2: Heavier gasses are still available up there, just in very small amounts. 10% at 1km, 1% at 2km, .1% at 3km, etc. still leaves some at 50km.

3: "Long enough timescales". You quoted it but didn't consider it.

4: The statement is about LIGHTER molecules and atoms. Not heavier ones. CFCs in the stratosphere aren't going to leave. He will.

Alan, the lower atmosphere is turbulent, gases get mixed regardless of density. Really high you up you get some density separation, but a better explanation is that the lighter the molecule, the higher it's thermal velocity. If you take a light atom at the top of the atmosphere like hydrogen or helium, there is a small probability that it will reach escape velocity and leave the Earth, while heavier atoms will fall back. This is helped by the solar wind.

Incidentally, we are very lucky that we have a cold layer at the tropopause which almost no water vapor can pass without condensing and falling down as rain. Water that gets above that point can dissociate by UV, and the hydrogen can escape. If more water reached higher into the atmosphere or more UV-radiation could pass lower, our oceans would have dried out by now.

What's that? Is it. Hmm. And what to do?
They say that earth could run out of Helium in 25 to 50 years.
They've said that about oil to; yet the known reserves keep increasing. Discovery.
Oh well, what do we do?

Ahh, first someone needs to set up a Helium Futures Market, trading Helium as a commodity like pork bellies or gold or oil.
But that may take a while.

In the meantime, go to your local cylinder gas company and buy a few cylinder of helium and stockpile the stuff.

I know, give your kid a cylinder of Helium as a stocking stuffer for Christmas. It's only $125 for a cylinder that can fill 175 9" balloons.

But don't fill any balloons. If the shortage is real and no new Helium is discovered; you'll be able to sell that cylinder of Helium in 20 years and pay for an ivy league college education!!

disclaimer #1: I am not sane (hmm that might be misconstrued)
disclaimer #2: no guarantee, warranty or representation, express or implied, is given as to the accuracy or completeness of the above Helium investment advise
disclaimer #3: Oh wait a minute; don't buy that Helium cylinder; it's a bad investment

"Most of the Uranium and Thorium in the world exists deep underground, so wherever there’s a Uranium... you’re bound to find a large deposit of Helium gas, too."

Look at this http://en.wikipedia.org/wiki/List_of_countries_by_uranium_reserves
I get it . No I don't get it.
Hmm? If you get it tell me.

Wait a minute. Look at that link Australia is loaded with Uranium.
And Nambia and Niger have more Uranium than the US. That's not right! Bring on the Helium wars!

Alan: In addition to the points Wow and Thomas made above, CFCs can be broken apart by UV photons. This results in free chlorine atoms, which are what do the damage to the ozone layer. The reactions are Cl + O3 -> ClO + O2 and ClO + O3 -> Cl + 2 * O2. Rinse and repeat. The chlorine atoms will eventually mix out of the stratosphere, but that takes decades, and in the meantime each chlorine atom can destroy hundreds if not thousands of ozone molecules.

O3 existing there because of the same UV light and that interception being why O3 is a necessary shield against UV damage to organisms (e.g. us).

I hate helium balloons.

They waste helium for frivolous purposes. They pollute the environment and kill animals for frivolous purposes.

So many of them float away -- either on accident when a little kid lets go of them, or even more released on purpose like in that image in the article -- and end up somewhere far away where a bird or other animal either eats them or gets tangled in the string and dies.

Stop using helium balloons!

I'm seeing a Bond Villain here. Hans Zeetwo? Dr. Noblegas? Monopolizing the world's helium and then waiting for it to become expensive/critical seems like a very bond villain thing to do. Frivolous, yes, but it might even raise some awareness.

On a more serious note, this may be part of a triple whammy coming this century. We are already starting to feel a pinch in medical radioisotopes, because not many places have realistic plans for replacing/building new research reactors. And at some point in the next few decades, the demand for rare earths for high-tech applications may outstrip what China is willing to export.

great stuff Ethan, this will be interesting. Are there are any thoughts on how much helium there might be on the moon?

eric: Rare-earths aren't that much of a problem. When China decided to limit exports, that only caused other mines that had closed because of China under-cutting their prices to re-open. There's a long-term issue with rare-earths, but the proximate issue is only a temporary pain.

Helium is also used as the 3rd-stage coolant for imaging equipment in hospitals, as that equipment has to be brought down to 4K for the superconducting magnets to do their stuff.

Liquid Nitrogen is used as the second stage. Standard refrigeration as the first.

The slightest little accidental addition of energy to the liquid helium sheath can cause a bubble, and that bubble causes a chain reaction as ALL the Helium boils off.

The equipment includes an emergency vent which lets out all the Helium if this happens in order to protect the equipment from exploding.

If you ever get a chance, make friends with somebody in Radiology and get them to give you the tour!

copernicus34 The talk about helium on the moon is He-3, an isotope that might be useful in fusion and that would them be worth the extremely high price of collecting it. .

It would be easier to gather up the helium that is found in our atmosphere. This is some orders of magnitude more expensive than today, but doable. We wouldn't get helium balloons, but we could have refrigeration like the one Vince describes, assuming some better recycling of the helium.

I actually had a similar thought but just the opposite. assuming we get fusion reactors working within the next decade or so we will be converting mass amounts of hydrogen into helium, every country every continent. we will be converting hydrogen from water to helium, which is of little industrial use. i imagined a day where we were worrying about the amount of helium we were releasing into the atmosphere and the effects that would have on the planet. while the helium may just evaporate off and leave us little worry we never get it back. regardless of the power source we find and how clever we think we are it's never renewable and we need to think of the long term results.

Helium can be distilled out of air with cryogenic equipment, so we will always be able to produce it for critical applications, it just won't be cheap enough for balloons anymore.

Also a lot of helium is produced as a byproduct of drilling for natural gas. The helium that comes from that is pretty much on a "use it or lose it" basis, we can't store it for later. This serves to make helium even cheaper than if we had to intentionally drill for the stuff.

@Thomas, thanks for the info. Yeh its kinda what i was thinking, awfully expensive (at least now) to try and acquire it on the moon. Are there any thoughts as to how much might be there though? I've yet to read anything pertaining to educated guesses on that.

Ethan, this is way off topic, but I can't find a way to contact you directly.

I've got an MP3 I want to send you of a song recorded by a local trio that I think you will like.

Where should I send it ?

Would it be possible to mix hydrogen with another gas to give it similar properties to helium whilst making it non-inflammable?

Mix it with Oxygen. It puts out fires then!

...You'd have water bombs instead of balloons - good one!
Seriously though we've got get this frivolous usage under control - they ain't making any more!

This isn't so much a "science" problem but rather one of economics... the allocation of a scarce resource.

In a free market the price of any scarce resource is directly proportional to it's scarcity. The more scarce, the more costly. As supplies of He dwindle the price rises and consumers will either pay more and lessen consumption (seeking substitutes) and/or suppliers will find or invent new economical ways to recover the decreasing marginal supplies.

A perfect example are petroleum resources. Not long ago we were hearing tales of "end of oil." Rising prices incented the development of new recovery technologies such as fracking that have pushed "the end" of recoverable oil supplies into the very distant future.

Sure, distortions occur but they are usually the result of policy rather than free-market dynamics.

The other place you find He is in Gas fields. Only in very small amounts but it is there. Qatar, one of the worlds major exporters of LNG, is one of the worlds main sources of Helium. In a few years they'll be the 2nd largest supplier in the world.
It is only cost effective because when making liquid natural gas the percentage of He is increased. When the price rises enough I suspect other gas companies will start extracting the He.

Glad the economists have it all worked out. Scarcity in one resource leads us to expend other, seemingly less scarce resources to recover more of it at greater cost. For instance, with fracking we can exchange relatively unpolluted fresh water, habitable property, wildlife habitate, and arable farmland for some more oil. We can do this indefinitely, for a definition of "we" and "indefinitely" that goes something like this:

"All humans who survive into the future will survive into the future with whatever standard of living people who survive into the future retain."

That this makes economics out to be a discipline that is as useful to anyone who gives a damn about humanity as the study of ballistics is to anyone who is concerned about gun violence. When triggers are pulled, bullets will fly. This is the "law" of bullets and triggers. When people want bullets to fly, but can't find any more triggers to pull, they will simply find something else to turn into a trigger, so that they continue to make the bullets fly. People who do not like the consequences will not like the consequences. Other people won't care. Some will be dead. Maybe many. Thus endeth the wisdom of whatsofuckingever it matters.

So is the helium just floating like a skin atop our atmosphere? Can we just scoop/skim it off and distill it?

I read somewhere the US govt is trying to sell off its helium dirt cheap, hadnt heard about the private part -- sounds like some conspiracy by helium vendor with big connections.. Maybe like debeers cornering tne diamond market, people will be swayed to give helium balloons as engagement presents instead of diamond ring

He man,

Nope, the helium does not just sit at the top of the atmosphere. The average velocity of helium atoms at temperatures ambient to the earth is greater than the earth's escape velocity. Therefore, the helium atoms escape from the earth's gravitational pull and wind up in space.

Does anyone actually mine helium? I thought it's a by product from natural gas production. If they do not go to the trouble extracting the helium from the natural gas, the helium is not going to stay in the ground. It would be released to the atmosphere when the natural gas is burnt.So, not filling a balloon with helium would not slow down (or speed up) the depletion of helium from the underground reservoirs. To have any effect, you need to slow down or speed up the extraction of natural gas.

I drill and process Helium for a living. You said "we mine it" that is incorrect. We drill for it, and it is generally found with Natural Gas in quantities less than 1%. The main reason why we are wasting helium is because it has been price controlled by the government, because during WW2 the government thought that dirigibles ie blimps were going to be the wave of the future for combat so they wanted to artificially control the price. It was classified a war time asset, why they haven't fixed it yet is just silly. Congress is currently working on rewriting a piece of legislation that will fix this and you will see the price of helium increase 20 fold. Whatever happens you can kiss your helium balloons good bye.

Another Republican disaster. Thanks, guys.

AC,

How is this a specifically Republican disaster. As Barton pointed out above, He is cheap because its price is kept artificially low due to its potentially military use during WWII. In case your education in history is deficient, there weren't many Republicans in the US government during that war. FDR was president, and certainly no Republican.

Though the two parties swapped places in the 60's or thereabouts, so your disassociation there is definitely not indicative of an error in AC's post.

I rather suspect it was a "strawman poe" where someone is attempting to get people to assert that this is what democrats "really think" and thereby neuter anyone who identifies as a democrat.

Wow,

My point was that I think we try to politicize things that aren't really political. I don't hold either Democrats or Republicans specifically responsible for the helium shortage. It's a bipartisan "F up".

Sean, my point was yours wasn't a rebuttal, and it was written to imply this is what it was.

It's a bipartisan F up because doing something on such a non-voter-issue could only go wrong and be noticed, since if it went OK, it wouldn't be noticed at all. Most of the people being voted are more interested in getting voted for again, hence Obama will not give all people in Gitmo that have not been found guilty as charged a pardon because he (well, his party) would be hammered in the pre-election smear campaigns for supporting terrorists.

I think they'd win more votes than they lose, but the other problem is that the politicians live in a bubble where they don't hear anything from the average Jenny Housecoat. So if the Washington pundits say it's not a vote winner, they will believe it.

oh no ! how can we survive without helium ??

For those folks who are planning on stockpiling that tank of helium left over from your last party; don't hold your breath. Helium, being an incredibly tiny, non-reactive molecule, seeps through just about any container you can put it in. Yes, even a steel tank. Over time, the helium will migrate through the steel, and your tank will go empty just like that sad, deflated balloon a week after the party. I have no idea how they hold it in the National Stockpile. Anyone care to enlighten us? (get it? en-LIGHTEN us?)

Every time a child has a birthday, a Higgs Boson dies

gregladen — Mon, 24 Sep 2012 12:35:04 +0000

Every time a child has a birthday, a Higgs Boson dies

Helium is rare. It is not produced in factories, and the places where it is found in the wild are unusual. When it gets lose, it tends to drift out into space. Simply put, it is a hard to find commodity with a limited availability. Helium is important in science. Big Science Projects like the Large Hadron Collider use Helium to cool magnets down to near absolute zero. Helium is also used in MRI machines, which have become an important part of medial research and diagnosis. Without a supply of Helium, a lot of important science projects would be in trouble.

From the BBC:

Prof Welton told BBC ... "We're not going to run out of helium tomorrow - but on the 30 to 50 year timescale we will have serious problems of having to shut things down if we don't do something in the mean time."

... "The reason that we can do MRI is we have very large, very cold magnets - and the reason we can have those is we have helium cooling them down.

"You're not going into an MRI scanner because you've got a sore toe - this is important stuff.

"When you see that we're literally just letting it float into the air, and then out into space inside those helium balloons, it's just hugely frustrating. It is absolutely the wrong use of helium."

For this reason, Welton and others as asking the question, should we be using Helium for uses such as making children's balloons float?

The balloon industry counters, noting that "Balloon Gas," which is what they call their product, is made of Helium recycled from medical uses and mixed with air, and that very little research grade Helium, if any, is lost to the process of engineering children's birthday parties. I suppose, though, that they could use hydrogen for the parties. It would make Chuckie Cheese a more...interesting...place.

Who says science doesn't have enough controversy!

gregladen Mon, 09/24/2012 - 08:35

Tags

Uncategorized

helium

http://www.washingtonpost.com/business/dwindling-helium-stockpile-has-c…

I wondered about that too. It seems to be remarkably inexpensive for such an important gas. Especially since we can't make it. Yet?

Someone had that idea at a rally in Armenia recently.

http://www.rawstory.com/rs/2012/05/04/exploding-hydrogen-balloons-at-ar…

We should totally switch to hydrogen for kid's balloons! What could go wrong? Just keep the candles at least 100 feet away.

Hydrogen is a perfectly good balloon gas and is used throughout most of the developing world - of course you have to take some precautions with the stuff and my bet is that there'll always be some moron who deliberately puts a light to a hydrogen balloon.

Even if party helium is recovered from medical facilities, helium is fairly easily purified to the level required by the big magnets - it's not as if the 'recycled' helium is not useful to science.

My personal favorite is to increase the number of fast breeder reactors to produce more helium and reprocess more power reactor fuel, but I doubt that'll be done. Nope - my bet is that we see helium supplies go down. Some clever person's got to think of a helium-free method of cooling low-temperature superconducting supermagnets.

@gwen: It's somewhat inexpensive because at the moment there's actually a huge amount being extracted. The stuff just oozes out of oil fields primarily in the USA. Helium is an alpha particle that picks up electrons so it's actually a product of nuclear decay; US oil fields just happen to have trapped an awful lot of the stuff. Anyway, what does come out during oil extraction simply has to be compressed and sold. There are no facilities to store huge amounts of helium for use in the distant future; since there is no hoarding, the current large supply keeps the gas somewhat affordable.

@MadScientist: I also had the initial thought that, in principle, it is easy to purify helium so that it can be reused in medical applications. (That it has a much lower boiling point than anything else is a major plus.) But it's not 100% effective (helium will slip out in places where other molecules won't, which is why one of its uses is as a leak detector), and if recycling costs more than using fresh gas, people will go for the fresh stuff.

why won't somebody think of the chipmunk voices

Isn't Helium is used to baloons to fly? Man I like it and think all the kids are.

@Eric: Yes, while the fresh stuff is cheaper, people will use that rather than recycled helium so I doubt many labs use recycled He. At some point in the future it will be economically viable to purify and recycle He. I think the biggest problems with the idea people have to raise the He prices are (1) if scientists pay that higher price then there's less money for research and (2) raising the prices does not address the future scarcity issue because we have no facilities for long-term storage of He extracted today and since He is essentially a byproduct of oil extraction, we can't really say "let's keep that He in the ground and tap it later".

Ohmygodno - hydrogen in toy balloons? If one were accidentally* ignited, it might, I dunno, knock over a leaf or something.

*Accidentally. Yeah, right. Kids with hydrogen-filled balloons and "accidental ignition".

I remember hoping as a kid that Helium would explode like Hydrogen (both low atomic number, both start with H, both in balloons) and I tried to make that happen. Turns out it's inert.

Weekend Diversion: Be Safe, Be Free!

esiegel — Sun, 19 Aug 2012 12:36:31 +0000

Weekend Diversion: Be Safe, Be Free!

“If you want total security, go to prison. There you're fed, clothed, given medical care and so on. The only thing lacking... is freedom.” -Dwight Eisenhower

One of the greatest feelings is the freedom to travel, whether by your own power or a mechanical motor, far faster than your own legs can take you. Kimya Dawson understands how delightful this is (and how much is missing when you can't have it), as you can likely tell from her song,

My Bike

I've always loved the feeling of biking, fast, along a deserted road, feeling the wind rush past me and seeing the world go by.

Image credit: Flickr user Hello Turkey Toe. And no, that's not me.

Many people (who have hair) also love the feel of the wind in their hair, but there's a trade-off for getting to experience that. Namely, in an accident, your head is completely unprotected from collisions with very solid objects such as cars or the pavement.

Image credit: German advertisement for "Initiative ProHelm".

For most of us, the tradeoff of wearing a helmet is well worth the reduction in fatalities and the severity of traumatic brain injury resulting from such accidents. I myself only began wearing a helmet after getting hit by a car while on my bicycle about a decade ago, but protecting my head is worth the discomfort, inconvenience and reduced field-of-view that comes with wearing a helmet.

But let's not kid ourselves; they are uncomfortable, inconvenient, sweaty and unsightly, even when worn by the best cyclists in the world.

Image credit: EPA / Gero Breloer; Stage 21 of the 2005 Tour de France.

I've seen a few attempts to make fashionable helmets, and while they've been amusing, I've yet to see something that I'd call a good option, just something that could perhaps be considered the least worst option.

Image credit: Jenn Hall of http://phillyrawrblog.blogspot.com/.

Because it's clearly smarter to be safe, I still hope everyone chooses to wear one. But I did wish there were better options than the currently existing helmets.

Apparently, someone else not only had the same idea, but went ahead and did something amazing about it.

Image credit: Hövding, Anna Haupt and Terese Alstin.

The woman shown, above, is wearing a bicycle helmet. Yes, yes she really is.

How's that?

In 2005, two students at Lund University in Sweden, Anna Haupt and Terese Alstin, came up with an idea for a bicycle helmet for adults that was completely invisible, but that would protect you in the event of a crash. Over the past seven years, they researched and developed Hövding, the world's first bicycle helmet that only self-activates when a crash is imminent.

Image credit: Hövding / Anna Haupt and Terese Alstin.

This remarkable device -- the collar around the woman's neck -- is an inflatable airbag (which takes just 0.1 seconds to inflate completely) powered by a cold helium inflator that's one of the smallest on the market. But what's truly amazing is the sensors, which are accelerometers and gyros, that pick up the abnormal movements of a cyclist in the early stages of an accident. That was the part that took the longest to design and test, and to meet the EU's strict helmet safety standards. How do the sensors work? From the site itself:

When Hövding is switched on, the sensors are constantly monitoring the wearer's movements. A bicyclist's movement patterns are divided into two different categories:

Normal movements: All bicycling in the city and on main roads, as well as all the normal movements you make before, during and after a bicycle ride such as running up and down steps, locking your bicycle, braking suddenly, giving way, pumping the tyres, etc. are defined as normal movements. Normal movements won't cause Hövding to inflate.

Abnormal movements: The movement patterns of a bicyclist in an accident are defined as abnormal movements. In an accident, a bicyclist's movements are completely different from those seen in normal bicycling. That's why the airbag is only triggered by accidents*.

To be able to distinguish between these two categories of movements, we've spent the past few years gathering data on the movement patterns of a large number of bicyclists in everyday bicycling situations. We've also re-enacted all known types of bicycling accident and recorded the movement patterns of bicyclists in these accidents. We staged fatal bicycling accidents using crash test dummies, while other bicycling accidents were re-enacted by stunt riders, male and female. We put all these movement patterns into our database and have developed a unique, patent pending, mathematical method for distinguishing between normal and abnormal movements. This method combined with the sensors is Hövding's brain.

The sensor turns on simply by snapping it closed around your neck, and can be recharged via USB.

Image credit: Hövding / Anna Haupt and Terese Alstin.

They have a number of videos and films showcasing the different aspects of this product, including its fashionability. The safety of this helmet is perhaps the most impressive, but my favorite video showcasing this innovative (innoventive?) helmet is this one, below, by Focus Forward Films.

What a remarkable invention and development by Anna and Terese, and here's hoping that the price comes down (they're currently $600 apiece) and that everyone can enjoy one of these amazing devices! Thanks to Larry Fedoruk for discovering this, and hope you enjoy knowing this exists as much as I do!

esiegel Sun, 08/19/2012 - 08:36

Tags

I cycle, and I always wear a helmet. I wouldn't think of cycling without one. Putting it on is as automatic as putting on the seat belt on the very rare occasions I drive.

This is the second time I've heard of the inflatable bike helmet. This time, there's more detail. I'm put off slightly by the price. What does make me doubtful is the possibility that it might not actually work in an emergency - there's no way of telling (as also applies to the airbags in cars) that they're functioning properly.
it's obvious that seatbelts and rigid bicycle helmets are capable of functioning as designed by just looking at them.

Uncomfortable? You haven't found the right helmet brand. A properly fitted helmet is not uncomfortable at all. (Different brands have different shapes, kind of the way certain brands of shoes are wider or narrower.)

Sweaty? Good helmets have lots of ventilation. If you have no hair (like me), wear a bandana under it.

Inconvenient? Easy to lock to your bike.

Unsightly? I suppose, but to a regular biker they look pretty natural.

The airbag helmet looks like a good idea for urban riding, but would not be much good for off road riding where flying over the handle bars is less than rare. If that thing inflated over your head, you would have a hard time finishing the ride.

Very nice. My wife would buy one.

And with cost improvements, Anna and Teresa will soon work on the fully inflatable body suit; so if I go over the handle bars.

Now wait just a minute, I might slip on a banana peel or fall off a cliff; and I suspect a fully inflatable body suit would protect against drowning and hypothermia not just inconvenient impact.

Yes of course, eventually Kevlar, we do not want accidental puncture.

Well done Anna and Teresa; keep going!

And every octogenarian should have a fully inflatable body suit; the baby boomers are aging fast.

My octogenarian father has slipped down the stairs twice in the last year. He needs an invisible helmet now.
And I'd wear an invisible helmet when driving an SUV (You know rollover accidents and head injury.)

Anna and Teresa, your market is much bigger than bicycle helmets. Go girls go!!!

I cycle every single day and I never use a bike helmet. Neither does anyone else in this city. There are no rules forcing you to wear them and as a result, everybody uses their bicycle all the time.

I wear my cycle helmet when going offroad because you can fall off for a number of reasons. But your helmet won't help you much when a car runs over you.

I've been riding on and off for 50 years without a helmet, but am considering one now. Bradley Wiggins has come out in public in favour, which may decide many people on the subject.

Oh, and the helmet above with knobbly bits outside is plain dangerous - it's designed to break necks at any decent speed.

Almost no one in the Netherlands uses helmets when biking to or from work, for shopping or cycling recreationally (the only ones using them are sports cyclists and small children until about the age of 12). A big part of this comes from excellent infrastructure where bike lanes are separated from motorized traffic (it helps that virtually all car drivers will have bikes too so they know how cyclists behave). Every dozen years or so there's a smallish debate about mandatory helmets but politicians quickly realise that forcing 16 million people (virtually the entire country) to wear helmets is a sure vote loser.

Invest in proper segregated infrastructure and maintain bike road surfaces and deaths will fall much quicker than mandating helmets.

Having said that I would never dream of cycling outside the country without a helmet where people are often forced into highways and on the same lanes as cars.

There's a nice youtube channel of a dutchy detailing specific infrastructure to make biking safer. Here's some nice ones:
http://www.youtube.com/watch?feature=player_detailpage&list=UU67YlPrRvs…
http://www.youtube.com/watch?feature=player_detailpage&list=UU67YlPrRvs…

Of course this does require using taxes and investing those. We call this civilisation. Too bad many Americans seem to think it's called socialism.

Brilliant! I saw this yesterday and it's absolutely the first 'helmet' I'd actually choose to wear. Pity though it's not yet suitable for off-road riding, but I suspect they'll sort that out soon. If I had spare €400 though, I would certainly use it for daily trundling around Berlin.

This one is also nice, mostly because I live about 100 meters (to the left) of 1:51, just where there is a small jump in the video: http://www.youtube.com/watch?v=_R8kX499D_M

There is no evidence cycle helmets are effective. Find some good studies if you believe otherwise.

Mandating helmets reduces cycling as many cities have found.

Also, these things have a LOT of teething troubles.

Nice design from those girls, although a bit thick for during the summer, it might become more advanced and something like a neckless.

@Dave Hodgkinson,

"There is no evidence cycle helmets are effective.

Here is one:
http://forum.fok.nl/topic/559306/1/25

Look at the graph from his boardcomputer how he went from 34km/h to zero, and scroll down to see the helmet and his face, and where the helmet abosorbed the collision.

"Seven percent of the case patients (bicyclists with head injury) were wearing helmets at the time of their head injuries, as compared with 24 percent of the emergency room controls (bicyclists with non head injury same hospital).. In regression analyses to control for age, gender, income, education, cycling experience, and the severity of the accident, we found that riders with helmets had an 85 percent reduction in their risk of head injury... We conclude that bicycle safety helmets are highly effective in preventing head injury. Helmets are particularly important for children, since they suffer the majority of serious head injuries from bicycling accidents." (N Engl J. Med 1969;320:1361-7)

And guys use a prostate relief bicycle seat too. But only if you're satisfied with the evidence.

Awesome invention,

but a bit expensive for only city driving. Those crash test videos show a stationary bike getting hit. And from their description it comes that "usual" movements are considered normal. What I'm concerned with is their sensor detecting any off-road riding as a crash situation. Am curious about the G treshold of those sensors. Do a little jump with a bike and the helmet might pop-up, causing you to have spent 600$ on nothing. Am also interested if these are "one time use only" devices, or if they can be re-used once activated.

Problem. When you wear a helmet, drivers don't take as much care over you any more.

The number of accidents go up.

In the Netherlands, wearing a helmet for everyday cycling (commuting/relaxing) is pretty pointless. I only wear a helmet when I'm out on my racing bike/"road bike" and cycling at 30 to 40 km/h (like the guy Chelle linked to).

When I'm not in the Netherlands, I probably wouldn't even dare get on a bike, with or without helmet.
(What can I say, I'm spoiled by the seperated cycle lines / routes.)

Hm, so instead of wearing a helmet it just looks like you're wearing a posture collar.

I'm not a cyclist, but I don't think bike helmets are unfashionable for the same reason I don't think harnesses with gear dangling from them (and a helmet) are unfashionable on a rock-climber -- it's gear for a sport, worn in the pursuit of said sport. Shoulder pads/shin guards look ridiculous when you're not on the (whichever kind of) football field, you know?

And think about this: When you reach your destination on your bike, you take your helmet off.

But you're still wearing your cycling shorts.

So,

why aren't you advocating for pedestrian and car helmets? Both have similar risk of head injury (actually the car drivers have a higher risk of serious head injury), and yet. You North Americans are obsessed with bike helmets instead of fostering a culture of cycling that would reduce the individual risk.

Michael, thanks for that awesome idea of promoting bicycle safety in order to reduce accidents rather than solely relying on helmets to save people when accidents occur! This is a revolutionary idea to us here in North America and will surely change everything about how bicycle safety is viewed.

I like it but I disagree with you about helmets. I mostly mtn bike and I think they look cool, but I gotta have the visor. Nutcase makes some nice ones for the city and I like Kali for MTB. I also motorcycle and as with MTB and now also skiing, I can't go without, like not wearing a seatbelt, I feel exposed.
I believe in personal choice, but I just cringe when I see others not wearing helmets. It takes so little to seriously damage your head even on a bike, fall just right on he gutter and you're out.
Also, I've been knocked out twice from head trauma, so I love helmets.

"It takes so little to seriously damage your head even on a bike, fall just right on he gutter and you’re out."

And you have to fall "just right on the gutter" and do so hard enough to kill yourself. These are not easy to arrange events.

Did you know there's enough energy in a four foot fall to kill you, if you "fall just right" and break your neck? That's right: if you're more than about 4' 8" tall, YOU CAN KILL YOURSELF FALLING OVER!

Pedestrians are more at risk than cyclists (in terms of real numbers) and drivers are more at risk in terms of numbers AND percentages of head injury.

Get them to wear a helmet too.

CB the foam shell with a thin plastic outer that is the bycicle helmet is only rated to protect your head in a 14 mph accident and since it can only disperse so much energy and that increases with the square of the speed, that falls to practically nothing very quickly.

Additionally, drivers will drive less carefully around a cyclist with a helment. Because they too believe that this is somehow proof against any collision and that death or serious injury is no longer a risk to a cyclist with some foam plastic on their head.

And injuries to cyclists increase when helmet use increases.

This innovative idea is really immpressive, but to make things more commercial we need products that could be cost-effective inorder to make them easily avialable for a common person.

Wow, I missed out on your comments here, but its clear that you mostly comment here just to disagree. And what a clever thing to say: "drivers will drive less carefully around a cyclist with a helmet.", that's just some lame talk coming from someone who doesn't like to put a pot on his/her head, if you have kids you'll hear excuses like that all the time. Everybody knows that a cyclist is fragile, helmet or no helmet.

"“drivers will drive less carefully around a cyclist with a helmet.”, that’s just some lame talk "

Nope, it's proven.

““drivers will drive less carefully around a cyclist with a helmet.”, that’s just some lame talk ”

Nope, it’s proven.

Fine, show the proof.

And when I have, you'll do what?

Ignore it ever happened? Say that the proof is wrong? Slate the source?

This is the mechanism:

http://en.wikipedia.org/wiki/Risk_compensation

And here is a survey:

http://www.bath.ac.uk/news/articles/releases/overtaking110906.html

for the measurements of this in fact.

> "And when I have, you’ll do what?

You haven't got the proof, because there is no proof.

I know the argument, and what they say is that when you 'have' to wear a helmet, than less people ride a bike, and with less cyclists around people take less notice of them, so it is not that “drivers will drive less carefully around a cyclist with a helmet.",that's it. No need to start whining about me to avoid the fact that your motivation is wrong, nice try though.

Oh dear. Do you feel silly now?

Wow,

Yes, it is proof. An average of 8.5 cm closer, on a total average of a 133 cm distance, also proves the dangers of our helmets, now let's trow them all away!

And no I don't feel silly, because there is this guy of a Dutch Cycling Union 'Theo Zeegers' who has been saying the things I wrote, it's a bunch of people that don't like to wear a helmet.

"Zeegers points to research by the Dutch traffic safety council which shows 60% of people would cycle less if helmets are made compulsory. And, he says, the public health institute RIVM calculates the cost to society of that would be much greater than the benefits brought by cycle helmets.

http://www.dutchnews.nl/news/archives/2012/02/helmets_make_cycling_less…

Hmmm.

Did I hear a WHOOSH of moving goaposts from you, chelle? I think I did.

" it’s a bunch of people that don’t like to wear a helmet."

Well, they don't like to wear a helmet because it's dangerous.

Is there something wrong with that? Or are you just pissed?

"Well, they don’t like to wear a helmet because it’s dangerous.

Now I know why you first wrote this before presenting your proof:

And when I have, you’ll do what?

Ignore it ever happened? Say that the proof is wrong? Slate the source?

Anyway I hope you'll never fall on your head when having an accident with your bike, I would miss you, take care.

What on earth are you pretending to be nice now? You're just being condescending.

"“Well, they don’t like to wear a helmet because it’s dangerous."

Now I know why you first wrote this before presenting your proof:"

See, this is an example of how you don't need any logical connection from one fact to whatever insane conclusion you wish to provide.

I note that you've ignore that evidence has been given of the statements.

And you've implied that they're wrong by claiming this is due to them not wanting to wear helmets. I.e. there was no other reason. When this is patently untrue.

Why?

God knows. Nobody knows why you get some insane little wasp thoughts in your head to come spewing out your mouth, but you do it.

Wow,

I said that the proof was correct, but that some people like to take this single fact as a claim for not having to wear a helmet, just like you say it is unsafe! while I say that their claim is mainly because they don't like wear it because of the burden.

When I draw a conclusion I also look at the bigger picture, your line of thinking is the same as with the safety-report of the LHC where it is said that single cosmic ray collisions don't cause any dangers, so it's all safe. While in reality you're only basing your conclusions on single events, you also need to look at the frequency & density numbers, and then the situation drastically changes.

"I said that the proof was correct"

What? In invisible ink? Funny how that would require this: "also proves the dangers of our helmets, now let’s trow them all away!" to be honest rather than sarcastic.

And stop with the histrionics, chelle.

You don't know that your sandwich bread is safe. but you have no ideological bone to pick with foodstuffs, so you don't pretend they really scare you.

The evidence that wearing a bicycle helmet is biase and unblinded survey with a "control" that included wearing a wig? Yeah. That's not evidence. That's actually pretty problematic, in fact.

Try reading the report, James.

I too decided that the Bath study was binworthy when I got to the bit about the wig - what's wrong with using a real woman as the subject?!

He may have a point, but I'd like to see the same study done with multiple cyclists (male, female, young, old - all with and without helmets), also constantly measuring their distance from the curb in the same way his system measured the distance from cars, and done in different countries.
How many of the close passes were due to narrowing of the road or other traffic effects?

I have another theory he could test: at work they gave me a fluoro jacket to wear when cycling. After a few days I noticed I was pushing the envelope more than usual, quite often chiding myself for taking silly risks. Maybe with helmets too there's an aspect of 'It's OK, I'm indestructible now'.

My helmet was the best investment in my life. I fell in a forest during my commute, head first on a pointy rock . I dislodged my elbow, I had a rib crushed and it was NOTHING compared to being probably dead after such a fall.
The helmet broke down but perfectly protected my head (I did not feel a thing)
I bought the same model and thanked the company - they rock.

I watched a friend go over his handlebars and land directly on his head when his front wheel came off at decent speed (due to improper use of the quick release). The energy absorbed by the crushed and broken foam would have been enough to crack his skull otherwise. Bicycle helmets save lives. Period.

To those flapping their arms and saying "Why don't we make drivers and pedestrians wear helmets too?": Regarding pedestrians, they're usually not travelling 20mph in a somewhat prone posture (i.e. head first). Meanwhile, drivers have an airbag, seatbelt, and car frame with crumple zones that absorb energy (just like the foam in a helmet).

I'm intrigued by the idea of inflatable garments for elderly people. Breaking a hip in a fall is a serious event. Perhaps augment the G sensors with ultrasonic sensors that activate when contact is about to be made at fast speed.

"The energy absorbed by the crushed and broken foam would have been enough to crack his skull otherwise."

Completel arrant made-up nonsense!

ABSOLUTELY untrue.

The standard allows for a fall of no more than four feet stationary on a bike or 12 miles per hour collision.

Any energy you assert would crush a skull would be barely intercepted by the foam of the helmet.

"binworthy when I got to the bit about the wig – what’s wrong with using a real woman as the subject"

What about some bloke wearing a wig to appear as possibly feminine makes the study binworthy? What's wrong about someone who is doing the test themselves who is a bloke NOT asking someone else to risk their safety and dressing up as feminine as possible to see what the gender effect would be?

No, you wish to bin the study for other reasons and are merely rationalising it.

"My helmet was the best investment in my life. I fell in a forest during my commute, head first on a pointy rock . I dislodged my elbow, I had a rib crushed"

So you're wearing a full-body helmet?

Yet more bollocks.

Why?

Why do you make up such rubbish all of you and even worse such obviously made up crap to boot?

How big of a balloon do you need to get to 120,000 feet high?

rallain — Wed, 26 May 2010 15:41:08 +0000

How big of a balloon do you need to get to 120,000 feet high?

I am still thinking about the Red Bull Stratos Jump. Sorry, but there is just tons of great physics here. Next question - how big of a balloon would you need to get up to 120,000 feet?

I am not going into the buoyancy details of Archimedes Principle - I think that was covered fairly thoroughly with the MythBusters floating lead balloon. However, in short, here is a force diagram for a floating balloon.

For a floating balloon, the buoyancy force must equal the weight of the whole thing. It turns out that the buoyant force is equal to the weight of the gas (or fluid) the object displaces. I can write that as:

Here this depends on the density of the air the object is floating in, the volume of the object and the gravitational field (g). For the gravitational force (the weight), it is important to remember that this is for the balloon, the stuff in the balloon and the payload.

Red Bull Balloon

What about the balloon that will be used for the Stratos Jump? According to the Red Bull Stratos site, here are some details.

Made from polyethylene 0.002 cm thick.
Uses helium (not hydrogen)
At the highest altitude, the balloon will be roughly 80 meters in diameter
The capsule (payload) is made of fiberglass. They don't list the mass.

So, what makes this high altitude balloon different than a normal balloon? First, the density of the air decreases as you get higher. This means that your ability to create buoyancy force goes down (you need a bigger balloon). Now, I will estimate how high this Stratos balloon will go. Let me start with the assumption that the balloon is a sphere with a diameter d and the mass of everything is m. Also, I will assume the buoyancy from the actual payload is small enough to ignore. This means that the following must be true.

This says that the object will rise until its density is equal to the density of the air. At least I don't have to worry about the gravitational field changing with height (since that canceled). What is next? Well, I know the density as a function of altitude (I calculated this before). I also know the volume. I can estimate the mass of the capsule and the balloon material. The thing I really don't know is the mass of the helium. Maybe this is small and I can ignore it - but probably not. The one thing I know about the helium is that it is at the same temperature and pressure as the atmospheric air. If I treat both gases as ideal gases, then:

Here, n is the number density, or how many particles per cubic meter. If both gases act as ideal gases and are at the same temperature and pressure, then they must have the same number density. I can write this as:

I really just need the ratio of helium mass (per particle) to the air mass. Air is a little tricky since it is not one type of molecule. Let me assume the air is 20% O₂ and 80% N₂. This would give an average particle mass of the air as 9.57 x 10^-26 kg. The particle mass for helium is simple since it is just He, this is a mass of 6.65 x 10^-27 kg. Let me write the total mass as:

Here the m_s stands for "mass of stuff" where stuff is the payload, the jumper, the balloon material etc. Now I get:

Now I want to solve for the density of air. I get:

Just calculate the density of air and I can look up the altitude that gives that density. Now for the values (some of this stuff I am just making up).

Mass of jumper = 80 kg
mass of capsule = 150 kg
mass of balloon = 360 kg (using a density of polyethylene of 930 kg/m^3)
volume of object = 2.68 x 10⁵ m^3

If I put in these values, I get a density of 0.0024 kg/m^3. Running my density calculation again, I get that this corresponds to an altitude of 34 km (112,000 feet). What about my estimates? With that density, the mass of the helium would be 44 kg - not too large compared to the mass of the material of the balloon. This tells me that I really need to know the mass of the capsule. Still, not too far off from the 120,000 feet Red Bull projects.

rallain Wed, 05/26/2010 - 11:41

Tags

Oh, you gotta listen to the podcast of this story - not how big a baloon, but how many balloons....

If I recall correctly, the price of Helium is quite high nowadays, since the supply is fixed, and the demand increasing ...

@_Arthur,

Interesting. I didn't even consider the price of helium. But .... the whole stunt is expensive anyway.

Why are Brown Dwarfs so Dim?

esiegel — Thu, 17 Apr 2008 00:05:33 +0000

Why are Brown Dwarfs so Dim?

Ahh, stars. Giant furnaces of nuclear fusion. Doing the stuff our Sun does, burning hydrogen fuel into helium (among other things) and emitting lots of visible light and energy in the process.

But when we take a look at brown dwarfs, they aren't like normal (i.e., main sequence) stars like our Sun. Instead of burning hydrogen into helium for their fuel, brown dwarfs don't generate enough pressure to make that happen; they can only burn hydrogen into deuterium.

Let's go over what the differences here are. A hydrogen nucleus is just a proton, with a mass of 938.272 MeV/c². (I use these units of mass because they're easy to turn into energy -- just multiply by c² and you get energy -- from E = mc².) A deuteron is a nucleus with a proton and a neutron (with mass 939.566 MeV/c²), but because they're bound together, the total mass of a deuteron is just slightly less than the mass of two protons, 1875.613 MeV/c². So when two protons fuse together to make a deuterium nucleus, they release 0.931 MeV of energy. Hang on -- that isn't quite right. They also have to conserve quantum numbers, like charge and lepton number. So it also needs to produce a positron and a neutrino: but not to worry; the positron will annihilate with an electron in the star and actually give you an extra 0.511 MeV of energy, bringing our total up to 1.442 MeV of energy release per fusion reaction.

In most stars, this is the first step in a chain reaction, leading to the production of Helium-4, which has a total mass of 3727.38 MeV/c², meaning that for every 4 protons fused into Helium-4, we gain (when we include the two positrons that are produced, and annihilate with electrons to make more energy) 26.73 MeV of energy. So here's how you make Helium-4 from deuterium and protons:

So at the end of the day, when they spend the same amount of mass (let's assume 4 protons) to make energy, brown dwarfs only give off 11% of the energy of normal stars. Add to that the fact that because they're so low mass, their rate of fusion is lower, and that's why brown dwarfs are so dim! So how dim are they? Perhaps this artistic reconstruction will give you an idea...

So next time you go outside, thank your friendly neighborhood Sun for being as warm, bright, and especially as massive at it is; otherwise the world would be a cold, lonely place.

esiegel Wed, 04/16/2008 - 20:05

Tags

Do all Stars Eventually Explode?

esiegel — Mon, 07 Apr 2008 07:47:38 +0000

Do all Stars Eventually Explode?

What's going to happen to all the stars in the Universe as they get older? Well, just as nothing can live forever, stars can't live forever also. Why? Because they run on fuel: burning hydrogen into helium, for example. When they run out of fuel, something's gotta give. Barbara Ryden reminds us of an excellent and appropriate quote by Dylan Thomas:

Do not go gentle into that good night.
Rage, rage against the dying of the light.

But what exactly happens to the star depends very sensitively on what the mass of the star is.

If you've got a tiny little star, less than about 40% of the mass of our Sun, it burns hydrogen to helium, and doesn't have enough mass to burn helium any further. Our Sun will be able to burn helium into Carbon and Oxygen, and stars significantly more massive will be able to burn Carbon and Oxygen into Neon, Silicon, and even more massive stars will eventually burn those into Iron. Most stars that fall into this category, when they run out of fuel that they're able to burn, will expand into a giant star, and then contract into a white dwarf.

White dwarfs don't burn anything, and are only "white" because they emit light due to the energy released from contracting gravitationally. (For a size comparison, the radius of Earth is 6371 km.) When they're done shrinking after a few billion more years, they stop emitting light, and become known as black dwarfs. But the most massive stars with iron cores, about 8 times the mass of the Sun or more, go supernova. When they start to contract, the pressure on the iron core becomes so intense that it starts to fuse the protons and electrons found in the iron atoms into neutrons! This causes a tremendous release of energy, known as a supernova explosion:

If the star is even more massive, the supernova can become even more powerful, and is known as a hypernova. Perhaps the most massive stars, dozens or even a hundred times as massive as our Sun, will go hypernova.

But maybe not! Astronomers from Ireland have been tracking exploded stars with the Hubble Space Telescope. They've been trying to determine what the masses of stars were before they went supernova, by trying to identify which star it was that exploded. Based on their findings, they've found that some stars may be massive enough that they don't go supernova or hypernova, but instead, when they stop burning their fuel, collapse directly into a black hole! Now this is neat, because in theory it isn't the most massive stars that do this, since their radii will be large enough that they won't directly collapse into black holes, but some special mass range. Here's a diagram I've found to illustrate the different possible fates of stars, based on their starting mass:

Now, what I want to know is, will the most massive stars in our galaxy, Eta Carinae, the Pistol Star, and LBV 1806-20, go hypernova when they die, or collapse directly to black holes? It might depend on where they are relative to the Eddington Limit, but for all we're sure of at this point, it might as well depend on whether they've read their Dylan Thomas or not!

esiegel Mon, 04/07/2008 - 03:47

Tags

iam doing a speach in the class about stars.so i wount to know if star change coulers

Fake...

There's really no need to substitute the word fuse for 'BURN' it's off putting, not scientific and does not the reader, rather it confuses them more!

he did not say that iron is the last thing the star can bern becasue berning iron kills the star by not giving it any thing to bern off that why big star collapes on its self