# Monthly Archives: August 2011

## Voyage dans l’Espace-Temps

Comme il est de nature impossible de voyager dans le passé, il va falloir comprendre pourquoi… c’est à travers des morceaux tangibles de la réalité que ce principe de Paradoxe de voyager dans le passé, complique même l’aspect Read the rest of this entry

## Time Travel; Past-no, Future-YES

Time travel is part of the predicted consequences by Einstein Special and general relativities. Special relativity (SR, also known as the special theory of relativity or STR) is the physical theory of measurement in inertial frames of reference proposed in 1905 by Einstein after the considerable and independent contributions of Hendrik Lorentz, Henri Poincare (and others) in the paper “On the Electrodynamics of Moving Bodies”.

It generalizes Galileo’s principle of relativity that all uniform motion is relative and that there is no absolute and well-defined state of rest (no privileged reference frames) from mechanics to all the laws of physics, including both the laws of mechanics and of electrodynamics, whatever they may be. Special relativity incorporates the principle that the speed of light is the same for all inertial observers regardless of the state of motion of the source.

This theory has a wide range of consequences among them twice on space-time and that some which have been experimentally verified, including counter-intuitive ones such as length contraction, time dilation and relativity of simultaneity, contradicting the classical notion that the duration of the time interval between two events is equal for all observers. (On the other hand, it introduces the space-time interval, which is invariant.) Combined with other laws of physics, the two postulates of special relativity predict the equivalence of matter and energy, as expressed in the mass–energy equivalence formula E = mc2, where c is the speed of light in a vacuum. The predictions of special relativity agree well with Newtonian mechanics in their common realm of applicability, specifically in experiments in which all velocities are small compared with the speed of light. Special relativity reveals that c is not just the velocity of a certain phenomenon namely the propagation of electromagnetic radiation (light) but rather a fundamental feature of the way space and time are unified as space-time. One of the consequences of the theory is that it is impossible for any particle that has rest mass to be accelerated more or equal to the speed of light.

The theory was originally termed “special” because it applied the principle of relativity only to the special case of inertial reference frames, i.e. frames of reference in uniform relative motion with respect to each other. Einstein developed general relativity to apply the principle in the more general case, that is, to any frame so as to handle general coordinate transformations, and that theory includes the effects of gravity.

The term is currently used more generally to refer to any case in which gravitation is not significant. General relativity is then the generalization of special relativity to include gravitation that you can have some details on our Seleani Youtube videos. In general relativity, gravity is described to be represented by curvature of space-time while special relativity was restricted to flat space-time. Just as the curvature of the earth’s surface is not noticeable in everyday life, the curvature of space-time can be neglected on small scales, so that locally, special relativity is a valid approximation to general relativity. The presence of gravity becomes undetectable in a sufficiently small, free-falling laboratory.

General relativity was published by Albert Einstein in 1916. It is the current description of gravitation in modern physics. General relativity generalizes special relativity and Newton’s law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or space-time.

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. Examples of such differences include gravitational time dilation (which is the basic mean of Future time travel possibility against the impossibility of travelling to the past), gravitational lensing, the gravitational redshift of light, and the gravitational time delay (which shows that 2 different space-time places evolve differently through time). General relativity’s predictions have been confirmed in all observations and experiments to date. Although general relativity is not the only relativistic theory of gravity, it is the simplest theory that is consistent with experimental data. However, unanswered questions remain, the most fundamental being how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity that we help us to make time travel possible where quantum and lightening physics can play a very big role in cosmology for more space and Universe exploration. This will be our next videos to talk how these conceptual topics are very interesting in today technology and Business life…

Einstein’s theory has important astrophysical implications. For example, it implies the existence of black holes, regions of space in which space and time are distorted in such a way that nothing, not even light, can escape as an end-state for massive stars. There is ample evidence that such stellar black holes as well as more massive varieties of black hole are responsible for the intense radiation emitted by certain types of astronomical objects such as active galactic nuclei or micro quasars. The bending of light by gravity can lead to the phenomenon of gravitational lensing, where multiple images of the same distant astronomical object are visible in the sky. General relativity also predicts the existence of gravitational waves, which have since been measured indirectly; a direct measurement is the aim of projects such as LIGO and NASA/ESA Laser Interferometer Space Antenna. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe that Stephen hawking is leading on deep universe exploration and took the black hole as his main tasks to achieve before passing away of his present life…

So in short, time travel could be possible only for the Future reference to the law of physics, with a concept called wormhole which is a hypothetical topological feature of space-time that would be, fundamentally, a “shortcut” through space-time. For a simple visual explanation of a wormhole, consider space-time visualized as a two-dimensional (2D) surface. If this surface is folded along a third dimension, it allows one to picture a wormhole “bridge” from a spacetime A to another space-time B; much like a tunnel with two ends each in separate points in spacetime, or it can be also known as two connecting black holes.

To cross a wormholes; it could actually be possible if exotic matter with negative energy density could be used to stabilize them. (Many physicists such as Stephen Hawking, Kip Thorne, and others believe that the Casimir effect is evidence that negative energy densities are possible in nature). Physicists have also not found any natural process which would be predicted to form a wormhole naturally in the context of general relativity, although the quantum foam hypothesis is sometimes used to suggest that tiny wormholes might appear and disappear spontaneously at the Planck scale (10 exp-43 s), and stable versions of such wormholes have been suggested as dark matter candidates. It has also been proposed that if a tiny wormhole held open by a negative-mass cosmic string had appeared around the time of the Big Bang, it could have been inflated to macroscopic size by cosmic inflation……To be continued in www.seleani.com