'Phys'
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Albert Einstein Institution
Albert Einstein
Albert Einstein ( pron.: / ˈ æ l b ər t ˈ aɪ n s t aɪ n / ; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen ) ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the general theory of relativity , one of the two pillars of modern physics (alongside quantum mechanics ). [ 2 ] [ 3 ] While best known for his mass–energy equivalence formula E = mc 2 (which has been dubbed "the world's most famous equation"), [ 4 ] he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect ". [ 5 ] The latter was pivotal in establishing quantum theory . Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field . This led to the development of his special theory of relativity .
The theory of relativity , or simply relativity , generally encompasses two theories of Albert Einstein : special relativity and general relativity . [ 1 ] (The word relativity can also be used in the context of an older theory, that of Galilean invariance .) Concepts introduced by the theories of relativity include: Measurements of various quantities are relative to the velocities of observers. In particular, space and time can dilate . Spacetime : space and time should be considered together and in relation to each other. The speed of light is nonetheless invariant, the same for all observers.
Theory of relativity
Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space —in the case of Earth from an altitude above the Kármán Line , (100 km). This article primarily addresses the process of controlled re entry of vehicles which are intended to reach the planetary surface intact, but the topic also includes uncontrolled (or minimally controlled) cases, such as the intentionally or circumstantially occurring, destructive deorbiting of satellites and the falling back to the planet of " space junk " due to orbital decay . Most objects entering the atmosphere are not released from rest just above it, but rather are entering at hypersonic speeds because they are on suborbital (e.g. ICBM reentry vehicles), orbital (e.g. the Space Shuttle ), or unbounded (e.g. meteors ) trajectories. Therefore, controlled atmospheric entry often requires special methods to protect against severe aerodynamic heating .
Atmospheric entry
Quark
A quark ( pron.: / ˈ k w ɔr k / or / ˈ k w ɑr k / ) is an elementary particle and a fundamental constituent of matter . Quarks combine to form composite particles called hadrons , the most stable of which are protons and neutrons , the components of atomic nuclei . [ 1 ] Due to a phenomenon known as color confinement , quarks are never directly observed or found in isolation; they can be found only within hadrons, such as baryons (of which protons and neutrons are examples), and mesons . [ 2 ] [ 3 ] For this reason, much of what is known about quarks has been drawn from observations of the hadrons themselves. There are six types of quarks, known as flavors : up , down , strange , charm , bottom , and top . [ 4 ] Up and down quarks have the lowest masses of all quarks. The heavier quarks rapidly change into up and down quarks through a process of particle decay : the transformation from a higher mass state to a lower mass state.Cosmology
Oceanography
Geology
Astronomy
Physics
Meteorology
Astronomy
Chemistry
Antigravity / Supergravity
Advanced Propulsion
Time Travel