"Why is there anything at all?" or "why is there something rather than nothing?" is a question about the reason for basic existence which has been raised or commented on by a range of philosophers and physicists, including Gottfried Wilhelm Leibniz, Ludwig Wittgenstein, and Martin Heidegger, who called it "the fundamental question of metaphysics".
Introductory points
There is something
No experiment could support the hypothesis 'There is nothing' because any observation obviously implies the existence of an observer.
Defining the question
The question is usually taken as concerning practical causality (rather than a moral reason for), and posed totally and comprehensively, rather than concerning the existence of anything specific, such as the universe or multiverse, the Big Bang, God, mathematical and physical laws, time or consciousness. It can be seen as an open metaphysical question, rather than a search for an exact answer.
On timescales
The question does not include the timing of when anything came to exist.
Some have suggested the possibility of an infinite regress, where, if an entity can't come from nothing and this concept is mutually exclusive from something, there must have always been something that caused the previous effect, with this causal chain (either deterministic or probabilistic) extending infinitely back in time.
Arguments against attempting to answer the question
The question is outside our experience
Philosopher Stephen Law has said the question may not need answering, as it is attempting to answer a question that is outside a spatio-temporal setting, from within a spatio-temporal setting. He compares the question to asking "what is north of the North Pole?"
Causation may not apply
The ancient Greek philosopher Aristotle argued that everything in the universe must have a cause, culminating in an ultimate uncaused cause. (See Four causes)
However David Hume argued that a cause may not be necessary in the case of the formation of the universe. Whilst we demand that everything have a cause because of our experience of the necessity of causes, the formation of the universe is outside our experience and may be subject to different rules.
The brute fact approach
In philosophy the brute fact approach proposes that some facts cannot be explained in terms of a deeper, more "fundamental" fact. It is in opposition to the principle of sufficient reason approach.
On this question Bertrand Russell took a brute fact position when he said, "I should say that the universe is just there, and that's all." Sean Carroll similarly concluded that "any attempt to account for the existence of something rather than nothing must ultimately bottom out in a set of brute facts; the universe simply is, without ultimate cause or explanation."
The question may be impossible to answer
Roy Sorensen has discussed that the question may have an impossible explanatory demand, if there are no existential premises.
Explanations
Something may exist necessarily
Philosopher Brian Leftow has argued that the question cannot have a causal explanation (as any cause must itself have a cause) or a contingent explanation (as the factors giving the contingency must pre-exist), and that if there is an answer it must be something that exists necessarily (i.e., something that just exists, rather than is caused).
Natural laws may necessarily exist, and may enable the emergence of matter
Philosopher of physics Dean Rickles has argued that numbers and mathematics (or their underlying laws) may necessarily exist. If we accept that mathematics is an extension of logic, as philosophers such as Bertrand Russell and Alfred North Whitehead did, then mathematical structures like numbers and shapes must be necessarily true propositions in all possible worlds.
Physicists such as Stephen Hawking and Lawrence Krauss have offered explanations (of at least the first particle coming into existence aspect of cosmogony) that rely on quantum mechanics, saying that in a quantum vacuum state, virtual particles and spacetime bubbles will spontaneously come into existence.
A necessary being bearing the reason for its existence within itself
Gottfried Wilhelm Leibniz attributed to God as being the necessary sufficient reason for everything that exists (see: Cosmological argument). He wrote:
"Why is there something rather than nothing? The sufficient reason... is found in a substance which... is a necessary being bearing the reason for its existence within itself."
A state of nothing may be impossible
The pre-Socratic philosopher Parmenides was one of the first Western thinkers to question the possibility of nothing, and commentary on this has continued. Some have argued that by definition, nothingness is the absence of any property or possibility, thus it would be a logical contradiction for something to be created from the lack of possibility of creation.
A state of nothing may be unstable
Nobel Laureate Frank Wilczek is credited with the aphorism that "nothing is unstable." Physicist Sean Carroll argues that this accounts merely for the existence of matter, but not the existence of quantum states, space-time, or the universe as a whole.
