We can't move through the vacuum of space faster than the speed of light, confirmed Jason Cassibry, associate professor of aerospace engineering at the University of Alabama's Propulsion Research Center in Huntsville. But no object actually moves through the Universe faster than the speed of light. The Universe is expanding, but the expansion does not have a speed; it has a speed per unit of distance, which is equivalent to a frequency or to an inverse time. One of the most surprising facts about the Universe is that if you do the conversions and take the inverse of the expansion rate, you can calculate the time it will take you to get out.
Travel and communication at a higher speed than light (also in FTL, superluminal or supercausal) are the conjectural propagation of matter or information at a higher speed than the speed of light (c). The special theory of relativity implies that only particles with mass at rest zero (i.e. e. There have been hypotheses about particles whose speed exceeds that of light (tachyon), but their existence would violate causality and involve time travel.
The scientific consensus is that they do not exist. The apparent or effective FTL, on the other hand, depends on the hypothesis that unusually distorted regions of space-time could allow matter to reach distant locations in less time than light in normal space-time (without distortion). Starting in the 21st century, according to current scientific theories, matter is required to travel at a lower speed than the speed of light (also STL or subluminal) with respect to the locally distorted space-time region. General relativity does not rule out apparent FTL; however, any apparent physical plausibility of the FTL is currently speculative.
Examples of apparent FTL proposals are the Albierre thruster, Krasnikov tubes, traversable wormholes, and the construction of quantum tunnels. Neither of these phenomena violates special relativity or creates causation problems, and therefore neither qualifies as FTL as described here. In the following examples, it may appear that certain influences travel faster than light, but they do not transmit energy or information faster than light, so they do not violate special relativity. For a terrestrial observer, objects in the sky complete a revolution around the Earth in one day.
Proxima Centauri, the closest star outside the Solar System, is about four and a half years away. In this frame of reference, in which Proxima Centauri is perceived to move on a circular trajectory with a radius of four light-years, it could be described as having a velocity many times greater than c, since the speed of the edge of an object moving in a circle is a product of the radius and angular velocity. It is also possible, in a geostatic view, for objects such as comets to vary their velocity from subluminal to superluminal and vice versa simply because the distance from Earth varies. Comets can have orbits that take them to more than 1000 AU.
The circumference of a circle with a radius of 1000 AU is greater than a light day. In other words, a comet at that distance is superluminal in a geostatic framework and therefore not inertial. If a laser beam passes through a distant object, the laser light point can be made to easily move across the object at a speed greater than c. Similarly, a shadow cast on a distant object can be made to move across the object faster than c.
In neither case does light travel from the source to the object faster than c, nor does any information travel faster than light. The speed at which two moving objects in a single frame of reference approach is called mutual or closing velocity. This can approach twice the speed of light, as in the case of two particles traveling at a speed close to that of light in opposite directions with respect to the frame of reference. Imagine two rapidly moving particles approaching each other from opposite sides of a collider type particle accelerator.
The closing speed would be the speed at which the distance between the two particles decreases. From the point of view of an observer at rest with respect to the accelerator, this speed will be slightly less than twice the speed of light. Special relativity doesn't prohibit it. It tells us that it is incorrect to use Galilean relativity to calculate the speed of one of the particles, as would be measured by an observer traveling with the other particle.
In other words, special relativity provides the correct formula for adding velocity to calculate said relative velocity. If a spacecraft travels at high speed to a planet within one light-year (measured in the Earth's resting frame) from Earth, the time needed to reach that planet could be less than one year as measured by the traveler's clock (although it will always be more than one year as measured by a terrestrial clock). The value obtained by dividing the distance traveled, determined in the framework of the Earth, by the time spent, measured by the traveler's clock, is known as adequate speed or adequate speed. There is no limit to the value of an adequate velocity, since an adequate velocity does not represent a velocity measured in a single inertial frame.
A light signal that left the Earth at the same time that the traveler always arrived at the destination before the traveler. The phase velocity of an electromagnetic wave, when traveling through a medium, can routinely exceed c, the vacuum speed of light. For example, this occurs in most glasses at X-ray frequencies. However, the phase velocity of a wave corresponds to the speed of propagation of a theoretical single-frequency component (purely monochrome) of the wave at that frequency.
Such a wave component must have an infinite extension and a constant amplitude (otherwise, it is not truly monochromatic) and therefore cannot transmit any information. Therefore, a phase velocity greater than c does not involve the propagation of signals with a velocity greater than c. Certain quantum mechanical phenomena, such as quantum entanglement, may give the superficial impression of allowing information to communicate faster than light. According to the non-communication theorem, these phenomena do not allow true communication; they only allow two observers in different places to view the same system simultaneously, with no way of controlling what either of them sees.
The collapse of the wave function can be seen as an epiphenomenon of quantum decoherence, which in turn is nothing more than an effect of the underlying local temporal evolution of the wave function of a system and of its entire environment. Since the underlying behavior does not violate local causality or allow FTL communication, it follows that neither does the additional effect of the collapse of the wave function, whether real or apparent. The EPR paradox refers to a famous thought experiment by Albert Einstein, Boris Podolsky and Nathan Rosen that Alain Aspect performed experimentally for the first time in 1981 and 1982 in the Aspect experiment. In this experiment, measuring the state of one of the quantum systems of an entangled pair apparently instantly forces the other system (which may be distant) to be measured in the complementary state.
However, information cannot be transmitted in this way; the answer to whether or not the measurement actually affects the other quantum system depends on the interpretation of quantum mechanics to which one subscribes. Special relativity postulates that the speed of light in a vacuum is invariant in inertial frames. In other words, it will be the same from any frame of reference that moves at a constant speed. The equations do not specify any particular value for the speed of light, which is an experimentally determined quantity for a fixed unit of length.
Since 1983, the SI unit of length (the meter) has been defined using the speed of light. Gerald Cleaver and Richard Obussy, a professor and student at Baylor University, theorized that manipulating the extra-spatial dimensions of string theory around a spaceship with an extremely large amount of energy would create a bubble that could cause the ship to travel faster than the speed of light. But in this case, the mass that represents the structure of space cannot be seen or detected directly, it does not become less dense as the Universe expands and simply provides a “stage” for raisins, or galaxies, to inhabit. Since you cannot travel faster than light, it could be concluded that a human can never travel farther from Earth than 40 light years away if the traveler is active between the ages of 20 and 60.
In other words, most of us understand the basic concept of special relativity, the “nothing can move faster than light” part, but we don't realize that the real Universe cannot be precisely described with special relativity alone. But space itself is expanding, and that explains the vast majority of the redshift we see. Albierre's distortion engine would work by creating a flat space-time bubble around the spacecraft and curving space-time around that bubble to reduce distances. If you're standing at point A and can travel one meter per second, it would take you 10 seconds to get to point B.
General relativity also recognizes that any means of travel faster than light could also be used to travel through time. In the Isaac Asimov Foundation series, humanity can travel from one planet to another, from one star to another, or across the universe using thrusters. If they then returned to Earth, the traveler would arrive on Earth thousands of years in the future. However, that doesn't mean that galaxies actually move through the Universe at faster speeds than light; the properties of the structure of space itself are constantly changing.
It is not because raisins move relative to the mass in which they are embedded, nor because individual galaxies move through the structure of space. However, let's suppose that you could somehow compress the space between you and point B so that the interval is now just one meter. Rather, it's due to the fact that mass itself, like the structure of space itself, is expanding, and the raisins (or galaxies) are ready to travel. .
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