Originally posted by robbebopThat's not ex nihilo, and in that process all quantum numbers must be conserved. A simple example is beta decay in a nucleus. Two new particles are produced, but overall the charge, spin, baryon and fermion numbers are all conserved.
if there is enough energy, matter can exist "out of nothing"
The best guess in theoretical physics I know of at the moment is that an inflationary era generated all the free energy in the universe. But one can insist on the necessity of a creator god based on the principle of sufficient reason, which roughly speaking states that every effect must have a cause. This is the basis for many theists claim that there must be a creator God. However, our understanding of physics is that processes are either allowed or ruled out depending on conservation laws but are not deterministic, so a radioactive atom may or may not decay in a time equal to its half life - we can state it's fifty fifty, but beyond that there's no rhyme or reason. What physics does is impose rules where otherwise anything could happen. So, there is no reason to suppose the principle of sufficient reason exists at anything beyond a stochastic level within the universe and not at all outside it. We have no empirical justification for claiming the laws of physics that we know work in domains outside the universe or that there are any analogous rules in such domains whatsoever. So I'd regard the principle of sufficient reason as a conspiracy of stochastic systems and valid only at a macroscopic level within this universe. Without a strong principle of sufficient reason arguments for the logical necessity of a creator seems less compelling.
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Originally posted by DeepThoughtBut can particels exist out of purely energy? Beta-decay is not out of energy, is it?
That's not ex nihilo, and in that process all quantum numbers must be conserved. A simple example is beta decay in a nucleus. Two new particles are produced, but overall the charge, spin, baryon and fermion numbers are all conserved.
Originally posted by robbebopWhat do you mean by "purely energy". In physics we often treat energy as a real thing that actually exists, but really it's a theoretical construct. It's usefulness in our theories is due to the way it is a conserved quantity. However there is no direct way of measuring it. One measures things like position, speed and mass and puts them into a theoretical formula to calculate an energy.
But can particels exist out of purely energy? Beta-decay is not out of energy, is it?
Now, in Quantum Field Theories there is no potential energy. There is only kinetic and mass energy (or more precisely there is only four momentum). This energy is always associated with a specific particle. So there is no such thing as "pure energy". What there are are gauge connections, photons and so forth, and you may regard bosons as being "pure energy", I don't think that this is right, they are particles and the energy is associated with a particle. However, if this is what you had in mind then yes, a photon with an energy of more than about 1 MeV can spontaneously "decay" into a positron electron pair provided there is another charged particle present to dump momentum into. So the only real difference is that in the case of beta decay the particle decaying is a fermion whereas for positron electron production it's a boson.
You might also be talking about vacuum fluctuations. These do not produce lasting particles, and there is no initial energy required to make it happen or final energy carried away.
Originally posted by DeepThoughtYes I was talking about those (but I didn't know the correct term in English 😳 ) , but now I see I am wrong. Thank you for your explanations.
You might also be talking about vacuum fluctuations. These do not produce lasting particles, and there is no initial energy required to make it happen or final energy carried away.
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Originally posted by DeepThoughtI think it more correct to say the big bang CONVERTED energy, transformed a previous source of energy rather than generating it directly. That makes it more sane, conservation of mass and energy wise.
That's not ex nihilo, and in that process all quantum numbers must be conserved. A simple example is beta decay in a nucleus. Two new particles are produced, but overall the charge, spin, baryon and fermion numbers are all conserved.
The best guess in theoretical physics I know of at the moment is that an inflationary era generated all the fr ...[text shortened]... sufficient reason arguments for the logical necessity of a creator seems less compelling.
I am thinking of the multi-universe hypothesis that says a parent universe generated a black hole that became the big bang that caused our universe to be born, the other side of the black hole or a white hole here, black hole there.