His report of life there covers a wide range of topics, such as marriage in heaven ( where all angels are married ), children in heaven ( where they are raised by angel parents ), time and space in heaven ( there are none ), the after-death awakening process in the World of Spirits ( a place halfway between Heaven and Hell and where people first wake up after death ), the allowance of a free will choice between Heaven or Hell ( as opposed to being sent to either one by God ), the eternity of Hell ( one could leave but would never want to ), and that all angels or devils were once people on earth.

The single-photon annihilation of an electron-positron pair, + →, cannot occur in free space because it is impossible to conserve energy and momentum together in this process.

The reverse reaction ( in free space, without an atomic nucleus ) is also impossible for this reason.

Many agates are hollow, since deposition has not proceeded far enough to fill the cavity, and in such cases the last deposit commonly consists of drusy quartz, sometimes amethystine, having the apices of the crystals directed towards the free space so as to form a crystal-lined cavity or geode.

The ratio of the speed of the electromagnetic wave to the speed of light in free space is called the velocity factor, and depends on the electromagnetic properties of the conductor and the insulating materials surrounding it, and on their shape and size.

In large impacts, the expanding vapor cloud may rise to many times the scale height of the atmosphere, effectively expanding into free space.

At low pressure, there was enough space between the gas atoms that the ions could accelerate to high enough speeds that when they struck another atom they knocked electrons off of it, creating more positive ions and free electrons in a chain reaction.

The resulting free space, is commonly considered a security risk due to the existence of file recovery software.

: is a unit vector in the direction of r, p is the ( vector ) dipole moment, and ε < sub > 0 </ sub > is the permittivity of free space.

The formalism of diffraction can also describe the way in which waves of finite extent propagate in free space.

Beginning with Maxwell's equations in free space:

Telecommunications engineering focuses on the transmission of information across a channel such as a coax cable, optical fiber or free space.

Transmissions across free space require information to be encoded in a carrier wave to shift the information to a carrier frequency suitable for transmission, this is known as modulation.

According to Maxwell's equations, the speed of light in a vacuum is a universal constant, dependent only on the electrical permittivity and magnetic permeability of free space.

where is the charge density, which can ( and often does ) depend on time and position, is the permittivity of free space, is the permeability of free space, and is the current density vector, also a function of time and position.

Inside a linear material, Maxwell's equations change by switching the permeability and permittivity of free space with the permeability and permittivity of the linear material in question.

Maxwell's equations take the form of an electromagnetic wave in an area that is very far away from any charges or currents ( free space ) – that is, where and are zero.

There also exist planetary-mass objects that orbit brown dwarfs and other bodies that " float free " in space not bound to any star ; however, the term " planet " is not always applied to these objects.

Since the stored energy in the barrier is less than the energy stored in a barrier-free region of the same length due to destructive interference, the group delay for the energy to escape the barrier region is shorter than it would be in free space, which according to Winful is the explanation for apparently superluminal tunneling.

Some predictions of general relativity differ significantly from those of classical physics, especially concerning the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light.

The preferred inertial motions are related to the geometry of space and time: in the standard reference frames of classical mechanics, objects in free motion move along straight lines at constant speed.

A simplified version of this is embodied in Einstein's elevator experiment, illustrated in the figure on the right: for an observer in a small enclosed room, it is impossible to decide, by mapping the trajectory of bodies such as a dropped ball, whether the room is at rest in a gravitational field, or in free space aboard an accelerating rocket generating a force equal to gravity.

Being relatively heavy and positively charged, alpha particles tend to have a very short mean free path, and quickly lose kinetic energy within a short distance of their source.

" In fairness to an accused, if, after consultation with his defense counsel, he knowingly and intelligently determines that his best interest is served by an Alford-type guilty plea, he should be free to choose this path.

The use of Stokes's law in Nernst's case, as well as in Einstein and Smoluchowski, is not strictly applicable since it does not apply to the case where the radius of the sphere is small in comparison with the mean free path.

In Judaism all human beings are believed to have free will and can choose the path in life that they will take.

The difference between the avalanche diode ( which has a reverse breakdown above about 6. 2 V ) and the Zener is that the channel length of the former exceeds the mean free path of the electrons, so there are collisions between them on the way out.

0. 01 torr is one order of magnitude above high vacuum, where fluids are in the free molecular flow regime, i. e. the mean free path of molecules is comparable to the size of the equipment.

During his time at the archives, Steiner wrote Die Philosophie der Freiheit ( The Philosophy of Freedom or The Philosophy of Spiritual Activity — Steiner's preferred English title ) ( 1894 ), an exploration of epistemology and ethics that suggested a path upon which humans can become spiritually free beings.

At atmospheric pressure the mean free path of air is about 70 nm.

The steel has a permeability many times that of free space and the core thus serves to greatly reduce the magnetizing current and confine the flux to a path which closely couples the windings.

Surface sensitivity in AES arises from the fact that emitted electrons usually have energies ranging from 50 eV to 3 keV and at these values, electrons have a short mean free path in a solid.

The path integral Monte Carlo method is a numerical approach for determining the values of free energies, based on quantum dynamical principles.

An optical depth of 1 corresponds to a mean free path, which is the distance, on average that a photon travels before scattering from a dust grain.

In telecommunication, free-space path loss ( FSPL ) is the loss in signal strength of an electromagnetic wave that would result from a line-of-sight path through free space ( usually air ), with no obstacles nearby to cause reflection or diffraction.

In fact, since the electromagnetic signals travel at the speed of light, and since every path has a geometrical length possibly different from that of the other ones, there are different air travelling times ( consider that, in free space, the light takes 3 μs to cross a 1 km span ).

In the study of wireless communications, path loss can be represented by the path loss exponent, whose value is normally in the range of 2 to 4 ( where 2 is for propagation in free space, 4 is for relatively lossy environments and for the case of full specular reflection from the earth surface — the so-called flat-earth model ).

Radio and antenna engineers use the following simplified formula ( also known as the Friis transmission equation ) for the path loss between two isotropic antennas in free space:

Erhard's decision, as economics director for the British and American occupation zones, to lift many price controls in 1948, despite opposition from both the social democratic opposition and Allied authorities, and his consistent advocacy of free markets, helped set the Federal Republic on its phenomenal growth path.

where the second factor is the mean free path and the square root ( with Boltzmann's constant k ) is the mean velocity of the particles.

Travelers had pushed along the relatively easy path to Fort Laramie with their luxury items but discarded them before the difficult mountain crossing ahead and after discovering that many items could be purchased at the forts or located for free along the way.

First, there is scattering from the wire boundaries, whose effect will be very significant whenever the wire width is below the free electron mean free path of the bulk material.