In astrophysics and cosmology, the anthropic principle is the philosophical consideration that observations of the physical Universe must be compatible with the conscious life that observes it.

: For an annotated list of textbooks and monographs, see physical cosmology.

In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 10 < sup > 78 </ sup > in volume, driven by a negative-pressure vacuum energy density.

Kepler described his new astronomy as " celestial physics ", as " an excursion into Aristotle's Metaphysics ", and as " a supplement to Aristotle's On the Heavens ", transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics.

In astrophysics and physical cosmology, Olbers ' paradox, named after the German astronomer Heinrich Wilhelm Olbers and also called the " dark night sky paradox ", is the argument that the darkness of the night sky conflicts with the assumption of an infinite and eternal static universe.

Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made ( particle physics ) to the behavior of the material Universe as a whole ( cosmology ).

One proposed timeline of the origin of space, from physical cosmology.

The modern era of physical cosmology began in 1917, when Albert Einstein first applied his general theory of relativity to model the structure and dynamics of the universe.

Also included are the predictions of cosmology, the results of the interpretation of quantum mechanics, the foundations of statistical mechanics, causality, determinism, and the nature of physical laws.

In physical cosmology, the term cosmos is often used in a technical way, referring to a particular space-time continuum within the ( postulated ) multiverse.

In physical cosmology, the cosmological constant ( usually denoted by the Greek capital letter lambda: Λ ) is equivalent to an energy density in otherwise empty space.

Hubble's law or Lemaître's law is the name for the astronomical observation in physical cosmology that: ( 1 ) all objects observed in deep space ( intergalactic space ) are found to have a doppler shift observable relative velocity to Earth, and to each other ; and ( 2 ) that this doppler-shift-measured velocity, of various galaxies receding from the Earth, is proportional to their distance from the Earth and all other interstellar bodies.

In physical cosmology, Big Bang nucleosynthesis ( or primordial nucleosynthesis, abbreviated BBN ) refers to the production of nuclei other than those of H-1 ( i. e. the normal, light isotope of hydrogen, whose nuclei consist of a single proton each ) during the early phases of the universe.

Modern cosmological ideas follow the development of the scientific discipline of physical cosmology.

The shape of the universe is a matter of debate in physical cosmology over the local and global geometry of the universe which considers both curvature and topology, though, strictly speaking, it goes beyond both.

Cosmologists normally work with a given space-like slice of spacetime called the comoving coordinates, the existence of a preferred set of which is possible and widely accepted in present-day physical cosmology.

Mount Meru (), also called Sumeru i. e. the " Excellent Meru " and Mahameru i. e. " Great Meru ", is a sacred mountain in Jain cosmology, Hindu as well as Buddhist cosmology and is considered to be the center of all the physical, metaphysical and spiritual universes.

It also forms the basis for the rigorous path integral formulation of quantum mechanics ( by the Feynman – Kac formula, a solution to the Schrödinger equation can be represented in terms of the Wiener process ) and the study of eternal inflation in physical cosmology.

In particle physics and physical cosmology, the Planck scale is an energy scale around 1. 22 × 10 < sup > 19 </ sup > GeV ( which corresponds by the mass – energy equivalence to the Planck mass 2. 17645 × 10 < sup >− 8 </ sup > kg ) at which quantum effects of gravity become strong.

In modern physical cosmology, the cosmological principle is the working assumption that observers on Earth do not occupy an unusual or privileged location within the universe as a whole, judged as observers of the physical phenomena produced by uniform and universal laws of physics.

In physical cosmology, first light refers to the light emitted from the first generation of hyperstars, formed less than a billion years after the big bang, which brought to an end cosmological dark ages.

The ultimate fate of the universe is a topic in physical cosmology.

Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed us to understand those laws.

Much of Kepler ’ s enthusiasm for the Copernican system stemmed from his theological convictions about the connection between the physical and the spiritual ; the universe itself was an image of God, with the Sun corresponding to the Father, the stellar sphere to the Son, and the intervening space between to the Holy Spirit.

" Galileo stated that the Copernican theory was not just a mathematical calculating tool, but a physical reality.

The Tychonic system ( or Tychonian system ) was a model of the solar system published by Tycho Brahe in the late 16th century which combined what he saw as the mathematical benefits of the Copernican system with the philosophical and " physical " benefits of the Ptolemaic system.

Riccioli then calculated the physical size that the stars they measured must have in order for them to both be as far away as was required in the Copernican theory to show no parallax, and have the sizes seen with the telescope.

The principle of relativity implies that the outcome of local experiments must be independent of the velocity of the apparatus, so the most important consequence of this principle is the Copernican idea that dimensionless physical values such as the fine-structure constant and electron-to-proton mass ratio must not depend on where in space or time we measure them.

The Copernican model of the solar system was regarded as a device to explain the observed positions of the planets rather than a physical description.

The Copernican revolution was arguably completed by Isaac Newton whose Philosophiae Naturalis Principia Mathematica ( 1687 ) provided a consistent physical explanation which showed that the planets are kept in their orbits by the familiar force of gravity.

It also reveals that the principle of linguistic relativity was so named because because Whorf saw that idea of his as having similar implications as Einstein's principle of physical relativity.

Avoidance of verbal and physical violence is also a part of this principle, although ahimsa recognizes self-defense when necessary, as a sign of a strong spirit.

Some proponents of the anthropic principle reason that it explains why the Universe has the age and the fundamental physical constants necessary to accommodate conscious life.

All versions of the principle have been accused of discouraging the search for a deeper physical understanding of the universe.

This principle has frequently been called the " Sapir – Whorf hypothesis ", after him and his mentor Edward Sapir, but Whorf called it the principle of linguistic relativity, because he saw the idea as having implications similar to Einstein's principle of physical relativity.

The Big Bang theory depends on two major assumptions: the universality of physical laws and the cosmological principle.

Most reconstructions of social communities by archaeologists rely on the principle that social interaction is conditioned by physical distance.

* Uncertainty in a physical variable as seen in for instance the uncertainty principle

The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 1821.

The principle of locality states that physical processes occurring at one place should have no immediate effect on the elements of reality at another location.

However, the principle of locality appeals powerfully to physical intuition, and Einstein, Podolsky and Rosen were unwilling to abandon it.

This could explain why all known fermions have baryon or lepton quantum numbers and provide a physical mechanism for the Pauli exclusion principle.

The physical principle of the guitar is therefore similar to the loudspeaker.

It appears to me, that the general conclusions established by Mesmer ’ s practice, with respect to the physical effects of the principle of imagination [...] are incomparably more curious than if he had actually demonstrated the existence of his boasted science " animal magnetism ": nor can I see any good reason why a physician, who admits the efficacy of the moral psychological agents employed by Mesmer, should, in the exercise of his profession, scruple to copy whatever processes are necessary for subjecting them to his command, any more than that he should hesitate about employing a new physical agent, such as electricity or galvanism.

However, the principle of special relativity generalizes the notion of inertial frame to include all physical laws, not simply Newton's first law.

The presence of fictitious forces indicates the physical laws are not the simplest laws available so, in terms of the special principle of relativity, a frame where fictitious forces are present is not an inertial frame:

For any inertial frame, the Coriolis force and the centrifugal force disappear, so application of the principle of special relativity would identify these frames where the forces disappear as sharing the same and the simplest physical laws, and hence rule that the rotating frame is not an inertial frame.

The process may involve causal relationships between intermediate events, but in any case the slippery slope schema depends for its soundness on the validity of some analogue for the physical principle of momentum.