Nothing comes from nothing

The idea that "nothing comes from nothing", as articulated by Parmenides, first appears in Aristotle's Physics:

τί δ᾽ ἄν μιν καὶ χρέος ὦρσεν ὕστερον ἢ πρόσθεν, τοῦ μηδενὸς ἀρξάμενον, φῦν; οὕτως ἢ πάμπαν πελέναι χρεών ἐστιν ἢ οὐχί.
[1]

The above, in a translation based on the John Burnet translation,[2] appears as follows:

 Yet why would it be created later rather than sooner, if it came from nothing; so, it must either be created altogether or not [created at all].

The Roman poet and philosopher Lucretius expressed this principle in his first book of De Rerum Natura (On the Nature of Things)

But by observing Nature and her laws. And this will lay
The warp out for us—her first principle: that nothing's brought
Forth by any supernatural power out of naught.
For certainly all men are in the clutches of a dread—
Beholding many things take place in heaven overhead
Or here on earth whose causes they can't fathom, they assign
The explanation for these happenings to powers divine.
Nothing can be made from nothing—once we see that's so,
Already we are on the way to what we want to know.[3]

He then continues on discussing how matter is required to make matter and that objects cannot spring forth without reasonable cause.

For if things were created out of nothing, any breed
Could be born from any other; nothing would require a seed.
People could pop out of the sea, the scaly tribes arise
Out of the earth, and winged birds could hatch right from the skies.
Born willy-nilly, every animal, both wild and tame,
Would inhabit cultivated land and wilderness the same.
The same tree would not always grow the same fruit—what might bear
An apple one time, might, the next, produce a quince or pear.
Since there would be no generating particles, then neither
Would certain things arise from only a certain kind of mother.
But since in fact each species rises from specific seeds,
Each thing springs from the source that has the matter that it needs,
The primary particles, and comes into the boundaries
Of light, and that's the reason every thing cannot give rise
To every other thing, because there is a separate power
In distinct things.[4]

The law of conservation of energy states that the total energy of an isolated system cannot change. The zero-energy universe states that the amount of energy in the universe minus the amount of gravity is exactly zero. That is the only kind of universe that could come from nothing, assuming such a zero-energy universe already is nothing.[5] Such a universe would need to be flat, a state which does not contradict current observations that the universe is flat with a 0.5% margin of error.[6]

Some physicists—such as Lawrence Krauss, Stephen Hawking, and Michio Kaku—define or defined 'nothing' as an unstable quantum vacuum that contains no particles.[7][8][9] This is different from the philosophical conception of nothing, which has no inherent properties and is not governed by physical laws.

Quantum mechanics proposes that pairs of virtual particles are being created from quantum fluctuations in this "empty" space all the time. If these pairs do not mutually annihilate right away, they could be detected as real particles, for example if one falls into a black hole and its opposite is emitted as Hawking radiation.

Alexander Vilenkin defines "nothing" as a universe of zero size: It is closer to nothing as one can get, but still not nothing.

• Antimetabole
• Empedocles
• Ex nihilo
• Melissus of Samos
• Principle of sufficient reason
• Problem of the creator of God
• Spontaneous symmetry breaking
• Vacuum energy

• Lucretius. (2007). The Nature of Things. Trans. A. E. Stallings. New York: Penguin Classics.

• Lucretius' De Rerum Natura, translated by William Ellery at the Internet Classics Archive