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... In particular, one would need to travel through space faster than the speed of light (which nobody can do) to avoid the singularity and end up in a different region. Thus, non-rotating black holes definitely seem to be excluded as passageways to distant lands. In the case of a rotating black hole, o ...
... In particular, one would need to travel through space faster than the speed of light (which nobody can do) to avoid the singularity and end up in a different region. Thus, non-rotating black holes definitely seem to be excluded as passageways to distant lands. In the case of a rotating black hole, o ...
PHYS3380_113015_bw - The University of Texas at Dallas
... are everywhere - quantum fluctuations. Normally, they are created as a particleantiparticle pair and they quickly annihilate each other. But near the horizon of a black hole, it's possible for one to fall in before the annihilation can happen, in which case the other one escapes as Hawking radiation ...
... are everywhere - quantum fluctuations. Normally, they are created as a particleantiparticle pair and they quickly annihilate each other. But near the horizon of a black hole, it's possible for one to fall in before the annihilation can happen, in which case the other one escapes as Hawking radiation ...
AN5
... the other hand photons have all-or-nothing interactions and only a small fraction will interact inside the sensitive volume of the counter. The size of that fraction depends on the energy of the photons. If the number of incident photons is large this does not matter; the incident flux can still be ...
... the other hand photons have all-or-nothing interactions and only a small fraction will interact inside the sensitive volume of the counter. The size of that fraction depends on the energy of the photons. If the number of incident photons is large this does not matter; the incident flux can still be ...
Thermodynamics
... at a higher temperature without the addition of energy. This is why it costs money to run an air conditioner. The Third Law states that the entropy of a pure crystal at absolute zero is zero. As explained above, entropy is sometimes called "waste energy," i.e., energy that is unable to do work, and ...
... at a higher temperature without the addition of energy. This is why it costs money to run an air conditioner. The Third Law states that the entropy of a pure crystal at absolute zero is zero. As explained above, entropy is sometimes called "waste energy," i.e., energy that is unable to do work, and ...
5.1 THERMAL QUANTITIES
... radiation. Other materials, such as concrete or mud however absorb the larger portion of short-wave radiation. The absorbed energy causes a rise in their temperature and this energy is emitted in the form of long-wave radiaticm. Glass is "opaque" to long-wave radiation and if it encloses the emitte ...
... radiation. Other materials, such as concrete or mud however absorb the larger portion of short-wave radiation. The absorbed energy causes a rise in their temperature and this energy is emitted in the form of long-wave radiaticm. Glass is "opaque" to long-wave radiation and if it encloses the emitte ...
Black body
A black body (also blackbody) is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a ""rough surface [that] reflects all incident rays completely and uniformly in all directions.""A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic radiation called black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition.A black body in thermal equilibrium has two notable properties:It is an ideal emitter: at every frequency, it emits as much energy as – or more energy than – any other body at the same temperature.It is a diffuse emitter: the energy is radiated isotropically, independent of direction.An approximate realization of a black surface is a hole in the wall of a large enclosure (see below). Any light entering the hole is reflected indefinitely or absorbed inside and is unlikely to re-emerge, making the hole a nearly perfect absorber. The radiation confined in such an enclosure may or may not be in thermal equilibrium, depending upon the nature of the walls and the other contents of the enclosure.Real materials emit energy at a fraction—called the emissivity—of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity of ε = 1.0. A source with lower emissivity independent of frequency often is referred to as a gray body.Construction of black bodies with emissivity as close to one as possible remains a topic of current interest.In astronomy, the radiation from stars and planets is sometimes characterized in terms of an effective temperature, the temperature of a black body that would emit the same total flux of electromagnetic energy.