This is a stupid question but I don't know anything about fusion:
How is it possible for X energy to create X+Y energy in output? Doesn't that violate some fundamental law of physics?
How is it possible for X energy to create X+Y energy in output? Doesn't that violate some fundamental law of physics?
2.01410177811 u + 3.01604928 u = 5.03015105811 u
4.002602 u + 1.008 u = 5.010602 u
5.03015105811 u - 5.010602 u = 0.01954905811 u
Thank you.
These heaver-than-iron elements are created in a very interesting and exotic process. When a large enough star dies it explodes in a supernova, and a huge amount of energy and neutrons are released in a very short period of time. This supernova generates enough energy and neutron material that small amounts of heavier elements like gold, platinum, etc. are created through exotic nuclear fusion reactions, even though these heavy fusion reactions are energy-absorbing.
It's interesting to think when you're wearing jewelry made from gold or platinum, all of those atoms in your jewelry were created during the death of a star.
The conversion is also very slow. And expensive. To make it this way it would cost a Quadrillion dollars an ounce.
https://www.scientificamerican.com/article/fact-or-fiction-l...
Once you get past the enormous energy costs to do this you have a secondary problem, all the gold produced this way is radioactive and it beta decays to.. Mercury.
The wikipedia page is pretty good, as always: https://en.wikipedia.org/wiki/Nucleosynthesis
Almost everything with mass of 90 or above comes predominantly from neutron star mergers, basically.
I'd be interested to know if we're in an element rich vein of the wider universe or if all the good stuff is more or less evenly distributed?
>Some whole galaxies have average metallicities only 1/10 of the Sun's. Some new stars in our galaxy have more metals in them than the original solar nebula that birthed the Sun and the planets did. So the amount of "metals" like oxygen and carbon can vary by a few orders of magnitude from star to star, depending upon it's age and history.
https://www.reddit.com/r/askscience/comments/9tujxn/are_the_...
I have no idea, though, but I'm pretty sure I watched a video about this.
That kind of expansion rate has to rival any explosion imaginable.
"Stars are made of quarks"
https://static.wikia.nocookie.net/memoryalpha/images/d/d9/Qu...
star stuff = sternzeug. stern stoff = star fabric
https://www.ling.upenn.edu/~beatrice/110/docs/uncleftish_beh...
“The nitrogen in our DNA,
the calcium in our teeth,
the iron in our blood,
the carbon in our apple pies
were made in the interiors of collapsing stars.
We are made of star stuff”.
– Carl Sagan We have calcium in our bones,
iron in our veins,
carbon in our souls,
and nitrogen in our brains.
93 percent stardust,
with souls made of flames,
we are all just stars
that have people names"
Nikita GillBut not because “you are like a drop in the ocean,” but because “you are like an ocean in a drop.”
The idea of soul can be objectionable when it is based on an immortal being or on a vitalist life-force (like “anima” of the Latin). But it seems fine when it is based on the psyche (like the “Psuche” of the Greek).
I embrace taboo words like soul because they 1. are common 2. are useful for referring to things that seem pretty important (like avoiding soulless companies or products or buildings) and 3. are challenging to my normal (scientific) understanding of the world.
Still, I’d be more comfortable if the poem referred to the “carbon of our souls” rather than “carbon in our souls.” Hmm…
I think it might be an allusion to alchemy. Basically, the alchemists believed that ash (what was left after burning something) was the soul of all things...And-- this is where my complete lack of understanding about science shows-- I'm pretty sure Ash has lots of carbon? It's, you know, poetic. Many have claimed that poems are the "language of paradox" so it's okay for it to be a little non-literal. My interpretation of it, though, is that the soul is something impure that you must burn away, or maybe that the soul is polluted by our own words and behavior. It's definitely not meant to be scientifically accurate.
carbon's oxides are all gaseous at standard temperature and pressure
little carbon, then, not none
You and I are complicated but we're made of elements Like a box of paints that are mixed to make every shade They either combine to make a chemical compound or stand alone as they are
- They Might Be Giants
13.5 billion years seems like the time required to create a star, have the star die and blow up, have all that material settle and create a new star, then the planets are formed, than enough time on one of those planets needs to pass for life to form, then complicated life.
You raise an interesting question though: what is the earlier point of time where the heavy elements were abundant enough for life (as we know it) to form? Just because we started existing at +13.5 billion years, it doesn't mean carbon based life couldn't have formed much earlier.
Therefore, life could have developed in a few tens to few hundreds of millions of years after the big bang. That's still true even if we assume that heavier elements are created mainly when neutron stars collide and not by super/hypernovas as we theorized before LIGO/Virgo observatories.
Consequently, we likely are not a "progenitor" civilization in the universe if we only consider planets formation. We might not see anyone out there either because there's a great filter for intelligent life to emerge (so the bottleneck is in our past) or because few/no civilizations get to have an impact on their host stars (the filter is in our future) that would allow us to see them.
That being said, I wasn't aware of how LIGO changed the understanding of how heavier elements are usually formed, guessing it changed the expected neutron star prevalence? Do you have any additional reading on that?
Regarding the second point have a look at https://www.ligo.org/science/Publication-GW170817Kilonova/in... . That isn't my field of specialization, so I am not sure about recent publications. At the time though this was a big deal as kilonovas seem to be the primary source of heavy nuclei in the universe. That particular event crested between 1/100th to 1/1000th solar masses worth of heavy ( heavier than iron) nuclei. This is a greater rate than supernovas estimations.
It's not about the prevalence, but about the light curves observed during the event AT 2017gfo. They indicate significant heavy metal ejection but, what's interesting, also production.
> mergers of neutron stars contribute to rapid neutron capture (r-process) nucleosynthesis
These two articles cite the relevant papers:
https://en.wikipedia.org/wiki/GW170817#Scientific_importance
https://en.wikipedia.org/wiki/Nucleosynthesis#Neutron_star_c...
Maybe for a main sequence star, but there other processes that involve nucleosynthesis.
Iron will not happily fuse further because this NEEDS energy and where would that energy come from?
"heavier than iron" elements are produced when a star explodes because that collapse produces enormous amounts of energy.
During the collapse, the outer edge of the star is accelerated to something like 20% of the speed of light, that is an ENORMOUS amount of energy slamming down on the core.
Lastly, neutron starts don't produce energy, they are the incompressible remnants of a dead star.
He does an excellent job explaining things and put it to me like this.
Elements to the Left of Iron can undergo fusion and release energy, Elements to the right can undergo fission and release energy.
Iron IS the line because it needs energy to do either of these.
All elements want to find stability, and Iron is that Element because it needs energy for either fission or fusion.
So yes, Iron is the dividing line and this is what makes it so stable.
Edit: forgot to link the chart when referencing left or right..
(Yes I know it's technically mesons at the scale we're talking about but it doesn't rhyme so there)
-- Yeah there are a few alternative designs, but nothing that seems to do the division. https://en.wikipedia.org/wiki/Alternative_periodic_tables
And really, i guess everything is physics if you get specific enough.
>all the atoms in our universe/galaxy/solar system with a mass up to that of iron are formed in the core of stars
Roughly 90% of the helium atoms in the universe were created via Big Bang nucleosynthesis.
all is a strong word
for example: the nuclear fusion experiment in the article, that would have produced a few atoms heaver that hydrogen
(not to mention all the nuclear bombs that had a fusion stage)
So think about two stars killing each other to make your jewelry.
https://www.energy.gov/sites/default/files/styles/full_artic...
Which I'm going to watch, because even though everything I hear about this company gives me insane Theranos vibes... Well, if they pull it off... They might light a bulb with fusion in my lifetime.
(And I though I had seen a similar segment on "Answer with Joe", but I can't find it.)
None of those would be opposable source, of course - there won't be any until they open a plant, publish data, etc...
In the meantime, I see a hype cycle brewing, and it makes me a bit uncomfortable - but, we'll see.
2.01410177811 u = 3.34449439340696e-24 g deuterium
3.01604928 u = 5.008267217094e-24 g tritium
17.6 MeV = 7.832863e-19 kWh energy
Divide through, and you will see that you need 4.27 ug/kWh of deuterium, and 6.39 ug/kWh of tritium.
A random source [1] says that New York will use 50.6 TWh per year by 2027. That would require ~216 kg/yr of deuterium and ~323/yr kg of tritium.
This is all assuming 100% efficiency. A quick read suggests 50% efficiency might be practical, so double those quantities.
Also, i could easily have messed up that calculation somewhere, so please do check it!
[1] https://www.buildingcongress.com/advocacy-and-reports/report...
Tritium however is far more rare with only trace amounts of it being available within nature and barely more than a kg produced per year. Producing the 100s of kgs required per year still seems to be an unsolved problem, although my quick searching shows there's a couple viable solutions for it.
Though in practice enough will be lost that probably they'll still be somewhat net consumers-- just not nearly to the extent predicted by a simple thermodynamic model.
Still, even if fusion becomes a net producer of tritium, the whole tritium-is-hard-to-get problem will likely be a constraint that we'll be fighting as we ramp up use of fusion power in the future.
https://en.wikipedia.org/wiki/Tritium#Production
And there's not much of it:
> According to a 1996 report from Institute for Energy and Environmental Research on the US Department of Energy, only 225 kg (496 lb) of tritium had been produced in the United States from 1955 to 1996.[a] Since it continually decays into helium-3, the total amount remaining was about 75 kg (165 lb) at the time of the report.
Isn't that going to cause a serious problem if it requires 323Kg/yr of tritium just to power New York City?
[1] https://www.sciencedirect.com/topics/earth-and-planetary-sci...
I'm not sure how tokomaks are expected to work; do you just add lithium and expect the tritium to get where it needs to go to keep the reaction going, or do you actively remove gases from vessel, filter out the tritium, and re-use it as fuel?
Either way, I don't imagine it'd be too hard to recapture the stuff.
i.e. it's completely harmless unless you eat it.
They spent a few hours covered in dust on their coats, and did a bunch of subsurface skin damage which manifested as third degree burns. Sepsis, not radiation poisoning, generally killed them.
FWIW, tritium and a phosphor granule encapsulated in glass microspheres have been developed for self-illuminating runway paint, but again, no one really uses it because tritium is stupid expensive, and again, it' loses half its brightness in only a decade.
On the other hand, I've been told that Trijicon will replace their tritium gun sights for the lifetime of the original owner. I plan to live long enough to cost them money...
We'll all be using RDSs by then ;) ?
> ...I've been told that Trijicon will replace their tritium gun sights for the lifetime of the original owner.
I didn't know this, thanks.
> When I initially decided to write The Magic of Recluce in the late 1980s, I'd been writing science fiction exclusively... I conveyed a certain dismay about the lack of concern about economic, political, and technological infrastructures in various fantasies then being written and published in the field...
> I faced the very real problem of creating a magic system that was logical... Most fantasy epics have magic systems. Unfortunately, many of them, particularly those designed by beginning authors, aren't well thought out, or they're lifted whole from either traditional folklore or gaming systems and may not exactly apply to what the author has in mind.
> I began by thinking about some of the features and tropes of traditional fantasy. One aspect of both legend and folklore that stuck out was the use of "cold iron" to break faerie magic, even to burn the creatures of faerie, or to stand against sorcery. Why iron? Why not gold or silver or copper? Not surprisingly, I didn't find any answers in traditional folklore or even contemporary fantasy. Oh, there were more than a few examples, but no real explanations except the traditional ones along the lines of "that's just the way it works."
> For some reason, my mind went back to astronomy and astrophysics and the role that nuclear fusion has in creating a nova... Each of these fusion reactions creates a heavier element and releases energy... The proton-proton reaction that produces iron, however, is different, because it is an endothermic reaction...
> At the same time, the fact that metals such as copper or silver conducted heat and electrical energy suggested that they were certainly less than ideal for containing electrical energy. Gold and lead, while far heavier than iron, do not have iron's strength, and other metals are too rare and too hard to work, particularly in a low-tech society.
> At this point, I had a starting point for my magic system. I couldn't say exactly what spurred this revelation, but to me it certainly made sense. Iron can absorb a great amount of heat. If you don't think so, stand on an iron plate barefoot in the blazing sun or in the chill of winter. Heat is a form of energy. In fantasy, magic is a form of energy. Therefore, iron can absorb magic and, by doing so, bind it.
https://www.lemodesittjr.com/the-books/saga-recluce/recluce-...
I always thought this is the interesting takeaway, both fusion and fission funnel their constituent matter towards iron, as the final stable state of matter. Far future civilizations will have a lot of iron on their hands.
The original atoms (exactly which atoms depends on the reactor, but let's assume it's deuterium and tritium) have a certain starting energy. When you fuse them together the resulting atom (helium-4, if you start with deuterium and tritium) moves it into a lower energy state.
Since the fused atom has lower energy than the input atoms, the fusion reaction releases the difference in energy, which you can then capture.
This is effectively what is happening with any energy generator.
The reason nuclear fusion is such a desirable goal is because it only takes a relatively small amount of mass to convert into a relatively large amount of useful energy, and the mass (the fuel) is relatively easy to obtain.
Like all energy generation, it's converting one type of energy into another, more convenient type, to do useful work. Like a hydroelectric dam converting the potential energy of water into more useful electrical energy. Energy is conserved when water spins a turbine, it's just that electrical energy is more useful for work than the potential energy of the water. Of course you can still use the potential (or kinetic) energy of the water directly, such as with a water mill. But the energy to work ratio is worse in that form (especially if the work to be done is far away from the watermill).
Whenever you build a fire you need to input some amount of energy to begin the chemical reaction that releases energy. In this instance we get not electrical energy, but energy in the form of infrared and visible light, to heat our home and light our way. Yet the total energy released by the fire far surpasses the energy you used to start the reaction, but because the wood's mass is consumed, energy is ultimately conserved. You have converted wood (not useful for heating your home) into infrared light (useful for heating your home).
Mass is energy at rest, hence equivalence with exception of massless particles like photons that have zero mass and non-zero energy. Also, photons travel with the speed of light in vacuum and cannot be found at rest in any frame of reference. Modern physics is fun, isn't it?
P.S. Neutrinos were thought to have zero mass as well, but according to the Standard model they have mass.
There's a threshold of energy required to attain this fusion reaction (otherwise there would be no light nuclei in the universe), and once the nuclei combine there's energy that is released, similar to how some chemical reactions can be exothermic in nature.
Same principle, different means.
The law you're referring to might be the conservation of energy, but that applies to non-nuclear reactions and is more accurately called the law of conservation of mass-energy. In this case the energy in times the mass at the start is still equal to the energy out times the mass at the end. For the energy to increase, the mass must decrease to produce the Y in your equation.
When fusion happens, two hydrogen atoms fuse together into one, losing a bit of mass in the process. The mass difference is converted into energy Y (using E=mc2).
In this case, Y was greater than X, so there was a net gain in useful energy.
In a sense it's no more mysterious (conservation of energy-wise) than adding the energy of a spark results in the energy of the wood fire.
i.e. energy is transformed, not created as you quite accurately write.
Fusion and fission are like that but for atoms instead of molecules.
But, O2 molecules, with their double bond, don’t take much energy to break apart. If they do, and then pair up with say a bunch of Hydrogen and Carbon atoms that were nearby in some long chain or something, they form bonds that are stronger - that take more energy to break - and you end up with some leftover energy. Water and CO2 molecules are an even lower energy configuration.
but the extra energy you get wasn’t exactly ‘in’ the oxygen bond though - any more than when you have a ball at the top of a hill it has potential energy ‘in’ it.
Energy in total is still conserved, but it makes engineering sense to compare the size of the starting fire to the total inferno created.
the "extra" comes from the mass
because matter is energy, you can use conversion energy to turn matter into its stored energy.