6 ms·

Can someone explain to me why fusion energy isn't violating the laws of physics?

by xutopia 8y ago

ianferrel 8y ago
Which laws do you think it violates? Are you asking where the energy comes from?
simonebrunozzi 8y ago
The Sun emanates energy using fusion. Why should it violate the laws of physics?
turbinerneiter 8y ago
E=m*c^2 Fusion is simply a reaction in which a higher amount of the mass of the involved matter is transformed to energy.
mikeyouse 8y ago
Think of it like rubbing two sticks together to start a fire -- You need to put enough energy into a system to maintain the subsequent high-energy reaction. In a fusion reaction, we're supplying the fuel (Deuterium/Tritium/Helium instead of wood) and the spark (electromagnetic/laser instead of fire) to provide enough energy for the fuel to sustain an ongoing energetic reaction. The primary difference is instead of the fuel disassembling due to the reaction (carbon chains in the wood combining with oxygen to form heat, CO2, ash and H2O), in a fusion reaction the energy is used to combine two molecules (usually two isotopes of hydrogen combining to make a single helium atom with excess energy/heat).
- gpderetta 8y ago
  https://en.m.wikipedia.org/wiki/Activation_energy https://en.m.wikipedia.org/wiki/Activation_energy
i_am_proteus 8y ago
Two light things[+] are fused[++] into one heavy thing[+] The total mass of the (new) heavy thing is a little bit less than the total mass of the (original) two light things. There is some missing mass! That missing mass is converted into energy in the process. The oft-quoted formula is: E = m * c^2 ('E' is the energy, 'm' is that missing mass, 'c' is the speed of light[+++]) This happens naturally in the sun (and other stars). It happens artificially in hydrogen bombs. Making it happen artificially in ways that let people harness the energy (and aren't just explosions) is the hard part, which is why the article is interesting. +atomic nuclei, typically isotopes of hydrogen and helium ++hence "fusion" +++in a vacuum
- jimmcslim 8y ago
  Probably dumb question... and one I probably knew the answer to at some stage... why does the equation showing the conversion from mass to energy involve the constant of the speed of light?
  - maxxxxx 8y ago
    E=mc2. The amount of energy in mass is determined by the speed of light. Not sure if I am phrasing this correctly...
    - mikekchar 8y ago
      I wonder if it would be more understandable to say that m = E/c2. In other words what we think of as mass is really just a measure of energy bound up in particles. There is a relationship between mass and the speed of light that people may or may not know about. As you accelerate a particle towards the speed of light, the mass actually increases. Since the mass increases, it's harder to accelerate, which means that you need more energy to make it go faster. To get it to the speed of light you would need infinite energy and it would have infinite mass. We can also rewrite the equation as c = sqrt(E/m). In other words, the speed of light is determined from the ratio of energy to mass in the system. When looked at from this perspective, it's not really that surprising that the ratio of energy to mass is a constant. What's kind of surprising is that this constant is the speed of light. Even just trying to figure out how the units might work is a bit mind bending -- m/s = sqrt(g/J) I think this is where you start to understand that the concept of space, time, energy and mass are all intertwined. We kind of think of them as separate things because from our macro perspective, that's how they look. Under the hood, though, they are all intricately bound together. The consequences of special relativity (where this equation came from) is that space, time, and mass are functions of energy, which is both super cool and super confusing :-)
  - epicureanideal 8y ago
    I don't think there's any "first principles" or philosophical/logical explanation for this... it's just an empirically determined fact, I think...
empath75 8y ago
It’s releasing energy contained within the mass of atomic nuclei
cookingrobot 8y ago
I used to be confused about how both fission and fusion can release energy. It turns out elements lighter than Iron release energy when they combine (fusion), and elements heavier than Iron release it when they split (fission). So for any element, it only releases energy as it gets closer to becoming Iron. https://en.wikipedia.org/wiki/Iron_peak https://en.wikipedia.org/wiki/Iron_peak
- Roboprog 8y ago
  There’s a certain amount of irony (iron-y?) that heavy fissionable materials are formed when fusion stalls: the core of a large star is turned into iron, fusion “goes out”, then the star collapses and goes supernova. Heavier elements are formed in the “bounce” when the outer layers of the star crush down the suddenly cold(er) core, converting the kinetic energy into reactions that absorb energy by fusing heavy elements. Or something along that line, anyway.
noetic_techy 8y ago
Do you think the sun violates the laws of physics? Fusion is a well known phenomena. https://en.wikipedia.org/wiki/Nuclear_fusion https://en.wikipedia.org/wiki/Nuclear_fusion
leephillips 8y ago
It doesn't; it only violates the laws of economics: https://progressive.org/op-eds/let-cut-our-losses-on-fusion-energy-180313/ https://progressive.org/op-eds/let-cut-our-losses-on-fusion-...
adrianmonk 8y ago
Not a physicist, but as I recall it's because the relevant curve describing energy states doesn't slope just one direction. It goes up and then down again: http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.html#c2 http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.htm... This means when talking about tiny nuclei (hydrogen and helium), moving to a bigger nucleus (fusion) takes you to lower energy (more stable) state and releases energy. But when you're talking huge nuclei, it's the opposite, and moving to a smaller nucleus takes you to a lower energy state and releases energy.

Can someone explain to me why fusion energy isn't violating the laws of physics?

ianferrel 8y ago

Which laws do you think it violates? Are you asking where the energy comes from?

simonebrunozzi 8y ago

The Sun emanates energy using fusion. Why should it violate the laws of physics?

turbinerneiter 8y ago

E=m*c^2 Fusion is simply a reaction in which a higher amount of the mass of the involved matter is transformed to energy.

mikeyouse 8y ago

Think of it like rubbing two sticks together to start a fire -- You need to put enough energy into a system to maintain the subsequent high-energy reaction. In a fusion reaction, we're supplying the fuel (Deuterium/Tritium/Helium instead of wood) and the spark (electromagnetic/laser instead of fire) to provide enough energy for the fuel to sustain an ongoing energetic reaction. The primary difference is instead of the fuel disassembling due to the reaction (carbon chains in the wood combining with oxygen to form heat, CO2, ash and H2O), in a fusion reaction the energy is used to combine two molecules (usually two isotopes of hydrogen combining to make a single helium atom with excess energy/heat).

gpderetta 8y ago
https://en.m.wikipedia.org/wiki/Activation_energy https://en.m.wikipedia.org/wiki/Activation_energy

i_am_proteus 8y ago

Two light things[+] are fused[++] into one heavy thing[+] The total mass of the (new) heavy thing is a little bit less than the total mass of the (original) two light things. There is some missing mass! That missing mass is converted into energy in the process. The oft-quoted formula is: E = m * c^2 ('E' is the energy, 'm' is that missing mass, 'c' is the speed of light[+++]) This happens naturally in the sun (and other stars). It happens artificially in hydrogen bombs. Making it happen artificially in ways that let people harness the energy (and aren't just explosions) is the hard part, which is why the article is interesting. +atomic nuclei, typically isotopes of hydrogen and helium ++hence "fusion" +++in a vacuum

jimmcslim 8y ago
Probably dumb question... and one I probably knew the answer to at some stage... why does the equation showing the conversion from mass to energy involve the constant of the speed of light?
- maxxxxx 8y ago
  E=mc2. The amount of energy in mass is determined by the speed of light. Not sure if I am phrasing this correctly...
  - mikekchar 8y ago
    I wonder if it would be more understandable to say that m = E/c2. In other words what we think of as mass is really just a measure of energy bound up in particles. There is a relationship between mass and the speed of light that people may or may not know about. As you accelerate a particle towards the speed of light, the mass actually increases. Since the mass increases, it's harder to accelerate, which means that you need more energy to make it go faster. To get it to the speed of light you would need infinite energy and it would have infinite mass. We can also rewrite the equation as c = sqrt(E/m). In other words, the speed of light is determined from the ratio of energy to mass in the system. When looked at from this perspective, it's not really that surprising that the ratio of energy to mass is a constant. What's kind of surprising is that this constant is the speed of light. Even just trying to figure out how the units might work is a bit mind bending -- m/s = sqrt(g/J) I think this is where you start to understand that the concept of space, time, energy and mass are all intertwined. We kind of think of them as separate things because from our macro perspective, that's how they look. Under the hood, though, they are all intricately bound together. The consequences of special relativity (where this equation came from) is that space, time, and mass are functions of energy, which is both super cool and super confusing :-)
- epicureanideal 8y ago
  I don't think there's any "first principles" or philosophical/logical explanation for this... it's just an empirically determined fact, I think...

empath75 8y ago

It’s releasing energy contained within the mass of atomic nuclei

cookingrobot 8y ago

I used to be confused about how both fission and fusion can release energy. It turns out elements lighter than Iron release energy when they combine (fusion), and elements heavier than Iron release it when they split (fission). So for any element, it only releases energy as it gets closer to becoming Iron. https://en.wikipedia.org/wiki/Iron_peak https://en.wikipedia.org/wiki/Iron_peak

Roboprog 8y ago
There’s a certain amount of irony (iron-y?) that heavy fissionable materials are formed when fusion stalls: the core of a large star is turned into iron, fusion “goes out”, then the star collapses and goes supernova. Heavier elements are formed in the “bounce” when the outer layers of the star crush down the suddenly cold(er) core, converting the kinetic energy into reactions that absorb energy by fusing heavy elements. Or something along that line, anyway.

noetic_techy 8y ago

Do you think the sun violates the laws of physics? Fusion is a well known phenomena. https://en.wikipedia.org/wiki/Nuclear_fusion https://en.wikipedia.org/wiki/Nuclear_fusion

leephillips 8y ago

It doesn't; it only violates the laws of economics: https://progressive.org/op-eds/let-cut-our-losses-on-fusion-energy-180313/ https://progressive.org/op-eds/let-cut-our-losses-on-fusion-...

adrianmonk 8y ago

Not a physicist, but as I recall it's because the relevant curve describing energy states doesn't slope just one direction. It goes up and then down again: http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.html#c2 http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.htm... This means when talking about tiny nuclei (hydrogen and helium), moving to a bigger nucleus (fusion) takes you to lower energy (more stable) state and releases energy. But when you're talking huge nuclei, it's the opposite, and moving to a smaller nucleus takes you to a lower energy state and releases energy.