As far as I can tell, physics does not presently posit an absolute state of nothingness before the Big Bang. It posits the quantum vacuum which may be pictured as a sort of fizzy effervescent soup underlying all things. This vacuum may have always been, or maybe it came about from something else. But for physics this vacuum is about as "nothing" as it gets. Here's a brief summary of the concept:
"In 1973, Edward Tryon, then at Columbia University, proposed a pioneering idea of how to apply quantum mechanics to the beginning of the Universe. Tryon suggested that quantum fuzziness does not only occur when measuring positions and velocities, but also applies to measurements of energy and time. In the world of the very small, it is possible to violate the law of conservation of energy for very short times, Tryon proposed, even if the net energy of the Universe is zero.
This is not as crazy as it seems. Think of a billiard ball lying quietly on the ground. If it is not moving, it has no kinetic energy. If we measure gravitational potential energy from the ground up, it also has no potential energy. The ball rests at a zero-energy state. Now turn the ball into an electron. According to Heisenberg’s uncertainty principle, we cannot localize an electron and tell its velocity simultaneously. The fuzziness inherent in the electron prohibits that.
Thus, in quantum mechanics, there is no zero-energy state. There is only the lowest possible energy state of a system, its ground state. Now, if there is an inherent uncertainty in the energy of a system, then the energy of the ground state can fluctuate. If we call this ground state a quantum vacuum, it follows that the quantum vacuum always has some structure to it. There is no such thing as a true vacuum in the sense of complete emptiness. Quantum mechanics forbids nothingness.
If there are energy fluctuations in a quantum vacuum, very interesting things can happen. For example, the E = mc2 relation tells us that energy and matter are interconvertible. A vacuum energy fluctuation can be converted into particles of matter. Sounds weird? Maybe, but it happens all the time. These particles are called virtual particles, living a fleeting existence before plunging back into the ever-busy quantum vacuum.
Tryon extrapolated the idea of quantum fluctuations to the Universe as a whole. He reasoned that if all that existed was a quantum vacuum, a bubble-like energy fluctuation out of this vacuum could have given rise to the Universe. Tryon proposed that the whole Universe is the result of a vacuum fluctuation, originating from what we could call quantum nothingness.
Tryon’s proposal falls into the category of universes with a beginning, but created out of nothing. However, nothingness here, as well as in all the other examples of quantum-created universes that followed Tryon’s inspiring idea, must be understood in terms of quantum mechanical nothingness, and not from an absolute nothingness that translates to complete emptiness. In physics you simply cannot get something out of nothing. Creation ex nihilo is not the way of nature."---- https://bigthink.com/13-8/universe-quantum-fluctuation/
"In 1973, Edward Tryon, then at Columbia University, proposed a pioneering idea of how to apply quantum mechanics to the beginning of the Universe. Tryon suggested that quantum fuzziness does not only occur when measuring positions and velocities, but also applies to measurements of energy and time. In the world of the very small, it is possible to violate the law of conservation of energy for very short times, Tryon proposed, even if the net energy of the Universe is zero.
This is not as crazy as it seems. Think of a billiard ball lying quietly on the ground. If it is not moving, it has no kinetic energy. If we measure gravitational potential energy from the ground up, it also has no potential energy. The ball rests at a zero-energy state. Now turn the ball into an electron. According to Heisenberg’s uncertainty principle, we cannot localize an electron and tell its velocity simultaneously. The fuzziness inherent in the electron prohibits that.
Thus, in quantum mechanics, there is no zero-energy state. There is only the lowest possible energy state of a system, its ground state. Now, if there is an inherent uncertainty in the energy of a system, then the energy of the ground state can fluctuate. If we call this ground state a quantum vacuum, it follows that the quantum vacuum always has some structure to it. There is no such thing as a true vacuum in the sense of complete emptiness. Quantum mechanics forbids nothingness.
If there are energy fluctuations in a quantum vacuum, very interesting things can happen. For example, the E = mc2 relation tells us that energy and matter are interconvertible. A vacuum energy fluctuation can be converted into particles of matter. Sounds weird? Maybe, but it happens all the time. These particles are called virtual particles, living a fleeting existence before plunging back into the ever-busy quantum vacuum.
Tryon extrapolated the idea of quantum fluctuations to the Universe as a whole. He reasoned that if all that existed was a quantum vacuum, a bubble-like energy fluctuation out of this vacuum could have given rise to the Universe. Tryon proposed that the whole Universe is the result of a vacuum fluctuation, originating from what we could call quantum nothingness.
Tryon’s proposal falls into the category of universes with a beginning, but created out of nothing. However, nothingness here, as well as in all the other examples of quantum-created universes that followed Tryon’s inspiring idea, must be understood in terms of quantum mechanical nothingness, and not from an absolute nothingness that translates to complete emptiness. In physics you simply cannot get something out of nothing. Creation ex nihilo is not the way of nature."---- https://bigthink.com/13-8/universe-quantum-fluctuation/