He clarified however that, “I am not an atheist”, preferring to call himself an agnostic, or a “religious nonbeliever.” Einstein also stated he did not believe in life after death, adding “one life is enough for me.” He was closely involved in his lifetime with several humanist groups.

Max Born FRS, FRSE (German pronunciation: [ˈmaks ˈbɔʁn] (listen); 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 1930s. Born won the 1954 Nobel Prize in Physics for his “fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function”.

It’s true that Einstein had a famous quote about how, “God does not play dice with the Universe.” But arguing against a fundamental randomness inherent to quantum mechanics — which is what the context of that quote was about — is arguing about how to interpret quantum mechanics, not an argument against quantum mechanics itself.

In fact, the nature of Einstein’s argument was that there might be more to the Universe than we can presently observe, and if we could understand the rules we have not yet uncovered, perhaps what appears to be randomness to us here might reveal a deeper, non-random truth. Although this position has not yielded useful results, explorations of the fundamentals of quantum physics continues to be an active area of research, successfully ruling out a number of interpretations involving “hidden variables” present in the Universe.

The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic, weak and strong interactions — excluding gravity) in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.

In theoretical physics, quantum nonlocality refers to the phenomenon by which the measurement statistics of a multipartite quantum system do not admit an interpretation in terms of a local realistic theory. Quantum nonlocality has been experimentally verified under different physical assumptions. Any physical theory that aims at superseding or replacing quantum theory should account for such experiments and therefore cannot fulfill local realism; quantum nonlocality is a property of the universe that is independent of our description of nature.

The field of quantum gravity is actively developing, and theorists are exploring a variety of approaches to the problem of quantum gravity, the most popular being M-theory and loop quantum gravity. All of these approaches aim to describe the quantum behavior of the gravitational field. This does not necessarily include unifying all fundamental interactions into a single mathematical framework. However, many approaches to quantum gravity, such as string theory, try to develop a framework that describes all fundamental forces. Such a theory is often referred to as a theory of everything. Others, such as loop quantum gravity, make no such attempt; instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces.

One of the difficulties of formulating a quantum gravity theory is that direct observation of quantum gravitational effects is thought to only appear at length scales near the Planck scale, around 10⁻³⁵ meters, a scale far smaller, and hence only accessible with far higher energies, than those currently available in high energy particle accelerators. Therefore, physicists lack experimental data which could distinguish between the competing theories which have been proposed.

Thought experiment approaches have been suggested as a testing tool for quantum gravity theories. In the field of quantum gravity there are several open questions - e.g., it is not known how spin of elementary particles sources gravity, and thought experiments could provide a pathway to explore possible resolutions to these questions, even in the absence of lab experiments or physical observations.

A theory of everything (TOE or TOE/ToE), final theory, ultimate theory, unified field theory or master theory is a hypothetical, singular, all-encompassing, coherent theoretical framework of physics that fully explains and links together all aspects of the universe. Finding a theory of everything is one of the major unsolved problems in physics.

Since the 1950s, it has been conjectured that quantum fluctuations of the spacetime metric might make the familiar notion of distance inapplicable below the Planck length. This is sometimes expressed by saying that “spacetime becomes a foam at the Planck scale”. It is possible that the Planck length is the shortest physically measurable distance, since any attempt to investigate the possible existence of shorter distances, by performing higher-energy collisions, would result in black hole production. Higher-energy collisions, rather than splitting matter into finer pieces, would simply produce bigger black holes.

In computing, an abstraction layer or abstraction level is a way of hiding the working details of a subsystem. Examples of software models that use layers of abstraction include the OSI model for network protocols, OpenGL, and other graphics libraries, which allow the separation of concerns to facilitate interoperability and platform independence.

John Archibald Wheeler (July 9, 1911 – April 13, 2008) was an American theoretical physicist. He was largely responsible for reviving interest in general relativity in the United States after World War II. Wheeler also worked with Niels Bohr in explaining the basic principles behind nuclear fission. Together with Gregory Breit, Wheeler developed the concept of the Breit–Wheeler process. He is best known for popularizing the term “black hole,” as to objects with gravitational collapse already predicted during the early 20th century, for inventing the terms “quantum foam”, “neutron moderator”, “wormhole” and “it from bit”, and for hypothesizing the “one-electron universe”. Stephen Hawking referred to him as the “hero of the black hole story”.

”It’s almost like the spacetime is a geometrical representation of the entanglement,” says Van Raamsdonk. “Take away all the entanglement and then you just eliminate the spacetime.” Engelhardt agrees. “Entanglement between quantum systems is important for the existence and emergence of spacetime,” she says. The duality suggested that the spacetime of our physical universe might simply be an emergent property of some underlying, entangled part of nature.

Van Raamsdonk credits the AdS/CFT correspondence for making physicists question the very nature of spacetime. If spacetime emerges from the degree and nature of entanglement in a lower-dimensional quantum system, it means that the quantum system is more “real” than the spacetime we live in, in much the same way that a 2-D postcard is more real than the 3-D hologram it creates. “That [space itself and the geometry of space] should have something to do with quantum mechanics is just really shocking,” he says.

Although string theory and loop quantum gravity both suggest that spacetime is emergent, the kind of emergence is different in the two theories. String theory suggests that spacetime (or at least space) emerges from the behavior of a seemingly unrelated system, in the form of entanglement.

Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attempt to develop a quantum theory of gravity based directly on Einstein's geometric formulation rather than the treatment of gravity as a force.

In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity.

The quantum Zeno effect (also known as the Turing paradox) is a feature of quantum-mechanical systems allowing a particle's time evolution to be slowed down by measuring it frequently enough with respect to some chosen measurement setting.

Sometimes this effect is interpreted as “a system cannot change while you are watching it”. One can “freeze” the evolution of the system by measuring it frequently enough in its known initial state.

The initial singularity is a singularity predicted by some models of the Big Bang theory to have existed before the Big Bang and thought to have contained all the energy and spacetime of the Universe. The instant immediately following the initial singularity is part of the Planck epoch, the earliest period of time in the history of our universe.

In physical cosmology, the baryon asymmetry problem, also known as the matter asymmetry problem or the matter–antimatter asymmetry problem, is the observed imbalance in baryonic matter (the type of matter experienced in everyday life) and antibaryonic matter in the observable universe. Neither the standard model of particle physics, nor the theory of general relativity provides a known explanation for why this should be so, and it is a natural assumption that the universe is neutral with all conserved charges. The Big Bang should have produced equal amounts of matter and antimatter. Since this does not seem to have been the case, it is likely some physical laws must have acted differently or did not exist for matter and antimatter. Several competing hypotheses exist to explain the imbalance of matter and antimatter that resulted in baryogenesis. However, there is as of yet no consensus theory to explain the phenomenon, which has been described as “one of the great mysteries in physics”.

The implication of CPT symmetry is that a “mirror-image” of our universe — with all objects having their positions reflected through an arbitrary point (corresponding to a parity inversion), all momenta reversed (corresponding to a time inversion) and with all matter replaced by antimatter (corresponding to a charge inversion) — would evolve under exactly our physical laws. The CPT transformation turns our universe into its “mirror image” and vice versa. CPT symmetry is recognized to be a fundamental property of physical laws.

The state of the universe, as it is, does not violate the CPT symmetry, because the Big Bang could be considered as a double sided event, both classically and quantum mechanically, consisting of a universe-antiuniverse pair. This means that this universe is the charge (C), parity (P) and time (T) image of the anti-universe. This pair emerged from the Big Bang epochs not directly into a hot, radiation-dominated era. The antiuniverse would flow back in time from the Big Bang, becoming bigger as it does so, and would be also dominated by antimatter. Its spatial properties are inverted if compared to those in our universe, a situation analogous to creating electron–positron pairs in a vacuum. This model, devised by physicists from the Perimeter Institute for Theoretical Physics in Canada, proposes that temperature fluctuations in the cosmic microwave background (CMB) are due to the quantum-mechanical nature of space-time near the Big Bang singularity. This means that a point in the future of our universe and a point in the distant past of the antiuniverse would provide fixed classical points, while all possible quantum-based permutations would exist in between. Quantum uncertainty causes the universe and antiuniverse to not be exact mirror images of each other.

However, it provides a natural and straightforward explanation for dark matter. Such a universe-antiuniverse pair would produce large numbers of superheavy neutrinos, also known as sterile neutrinos.

Vacuum energy is an underlying background energy that exists in space throughout the entire Universe. The vacuum energy is a special case of zero-point energy that relates to the quantum vacuum.

Quantum foam or spacetime foam is a theoretical quantum fluctuation of spacetime on very small scales due to quantum mechanics. The theory predicts that at these small scales, particles of matter and antimatter are constantly created and destroyed. These subatomic objects are called virtual particles. The idea was devised by John Wheeler in 1955.

A virtual particle is a theoretical transient particle that exhibits some of the characteristics of an ordinary particle, while having its existence limited by the uncertainty principle. The concept of virtual particles arises in the perturbation theory of quantum field theory where interactions between ordinary particles are described in terms of exchanges of virtual particles. A process involving virtual particles can be described by a schematic representation known as a Feynman diagram, in which virtual particles are represented by internal lines.

Virtual particles do not necessarily carry the same mass as the corresponding real particle, although they always conserve energy and momentum. The closer its characteristics come to those of ordinary particles, the longer the virtual particle exists. They are important in the physics of many processes, including particle scattering and Casimir forces. In quantum field theory, forces—such as the electromagnetic repulsion or attraction between two charges—can be thought of as due to the exchange of virtual photons between the charges. Virtual photons are the exchange particle for the electromagnetic interaction.

Physics relies on conservation laws, which govern how energy and information can change within a system. The conservation of energy states that the total amount of energy in a closed system (like the universe) must stay constant. In classical physics, information can be copied and deleted, but in quantum mechanics, the conservation of quantum information means that information cannot be created or destroyed. This is demonstrated by the no-cloning and no-deleting theorems. The no-hiding theorem further shows that the wave function, which contains all relevant information about a physical system, is conserved as it moves from one Hilbert space to another during unitary time evolution. The conservation of entropy in quantum systems also suggests that information is conserved, as quantum states and mixed states (a combination of quantum states) remain unchanged during unitary evolution.

A blockchain is a distributed ledger with growing lists of records (blocks) that are securely linked together via cryptographic hashes. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (generally represented as a Merkle tree, where data nodes are represented by leaves). The timestamp proves that the transaction data existed when the block was created. Since each block contains information about the previous block, they effectively form a chain (compare linked list data structure), with each additional block linking to the ones before it. Consequently, blockchain transactions are irreversible in that, once they are recorded, the data in any given block cannot be altered retroactively without altering all subsequent blocks.

In mathematics, the complex plane is the plane formed by the complex numbers, with a Cartesian coordinate system such that the x-axis, called the real axis, is formed by the real numbers, and the y-axis, called the imaginary axis, is formed by the imaginary numbers.

In the simple case n = 1, the group U(1) corresponds to the circle group, consisting of all complex numbers with absolute value 1, under multiplication. All the unitary groups contain copies of this group.

The modern theory of antimatter began in 1928, with a paper by Paul Dirac. Dirac realised that his relativistic version of the Schrödinger wave equation for electrons predicted the possibility of antielectrons. These were discovered by Carl D. Anderson in 1932 and named positrons from “positive electron”. Although Dirac did not himself use the term antimatter, its use follows on naturally enough from antielectrons, antiprotons, etc. A complete periodic table of antimatter was envisaged by Charles Janet in 1929.

The Feynman–Stueckelberg interpretation states that antimatter and antiparticles are regular particles traveling backward in time.

The anthropic principle, also known as the “observation selection effect”, is the hypothesis, first proposed in 1957 by Robert Dicke, that there is a restrictive lower bound on how statistically probable our observations of the universe are, because observations could only happen in a universe capable of developing intelligent life. Proponents of the anthropic principle argue that it explains why this universe has the age and the fundamental physical constants necessary to accommodate conscious life, since if either had been different, we would not have been around to make observations. Anthropic reasoning is often used to deal with the notion that the universe seems to be finely tuned for the existence of life.

The characterization of the universe as finely tuned suggests that the occurrence of life in the universe is very sensitive to the values of certain fundamental physical constants and that the observed values are, for some reason, improbable. If the values of any of certain free parameters in contemporary physical theories had differed only slightly from those observed, the evolution of the universe would have proceeded very differently and life as it is understood may not have been possible.

In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles.
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The anthropic principle is an argument about the reason the fine-structure constant has the value it does: stable matter, and therefore life and intelligent beings, could not exist if its value were very different. α needs to be between around 1/180 and 1/85 to have proton decay to be slow enough for life to be possible.

Intelligent design (ID) is a pseudoscientific argument for the existence of God, presented by its proponents as “an evidence-based scientific theory about life''s origins”. Proponents claim that “certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection.”

The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life compared to the apparently high a priori likelihood of its existence. As a 2015 article put it, “If life is so easy, someone from somewhere must have come calling by now.”

The Great Filter is one possible resolution of the Fermi paradox. It posits that in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there exists some particular barrier to development that makes detectable extraterrestrial life exceedingly rare.

Most of the alien civilizations that ever dotted our galaxy have probably killed themselves off already.

That's the takeaway of a new study, published Dec. 14 to the arXiv database, which used modern astronomy and statistical modeling to map the emergence and death of intelligent life in time and space across the Milky Way. Their results amount to a more precise 2020 update of a famous equation that Search for Extraterrestrial Intelligence founder Frank Drake wrote in 1961. The Drake equation, popularized by physicist Carl Sagan in his “Cosmos” miniseries, relied on a number of mystery variables — like the prevalence of planets in the universe, then an open question.

This new paper, authored by three Caltech physicists and one high school student, is much more practical. It says where and when life is most likely to occur in the Milky Way, and identifies the most important factor affecting its prevalence: intelligent creatures' tendency toward self-annihilation.

All known fermions, the particles that constitute ordinary matter, have a spin of ½. The spin number describes how many symmetrical facets a particle has in one full rotation; a spin of ½ means that the particle must be rotated by two full turns (through 720°) before it has the same configuration as when it started.

In quantum mechanics, the Pauli exclusion principle states that two or more identical particles with half-integer spins (i.e. fermions) cannot occupy the same quantum state within a quantum system simultaneously. This principle was formulated by Austrian physicist Wolfgang Pauli in 1925 for electrons, and later extended to all fermions with his spin–statistics theorem of 1940.

The new scrutiny picked up a background blur in the images that had escaped past researchers. In relatively soft collisions just barely breaking the proton open, most of the momentum was locked up in the usual three quarks: two ups and a down. But a small amount of momentum appeared to come from a “charm” quark and charm antiquark — colossal elementary particles that each outweigh the entire proton by more than one-third.