In physics, spacetime is any mathematical model that fuses the three dimensions of space and the one dimension of time into The before-after relationship observed for timelike-separated events remains unchanged They are connected by a string which is capable of only a limited amount of stretching before breaking. Understanding gravity—warps and ripples in space and time .. ripple will stretch one arm of the L-shaped structure before stretching the other. The reason is that space and time aren't quite independent. And this relationship bends and twists based on how heavy stuff is. . sit idle in space — it bends spacetime around it, like a metal ball tugging on stretched fabric.
General relativityin addition, provides an explanation of how gravitational fields can slow the passage of time for an object as seen by an observer outside the field. In ordinary space, a position is specified by three numbers, known as dimensions.
Einstein's Theory of General Relativity: A Simplified Explanation
In the Cartesian coordinate systemthese are called x, y, and z. A position in spacetime is called an event, and requires four numbers to be specified: Spacetime is thus four dimensional. An event is something that happens instantaneously at a single point in spacetime, represented by a set of coordinates x, y, z and t. The word "event" used in relativity should not be confused with the use of the word "event" in normal conversation, where it might refer to an "event" as something such as a concert, sporting event, or a battle.Space and Time into a single Continuum
These are not mathematical "events" in the way the word is used in relativity, because they have finite durations and extents. Unlike the analogies used to explain events, such as firecrackers or lightning bolts, mathematical events have zero duration and represent a single point in spacetime.
The path of a particle through spacetime can be considered to be a succession of events. The series of events can be linked together to form a line which represents a particle's progress through spacetime. That line is called the particle's world line.
It was only with the advent of sensitive scientific measurements in the mids, such as the Fizeau experiment and the Michelson—Morley experimentthat puzzling discrepancies began to be noted between observation versus predictions based on the implicit assumption of Euclidean space.
Each location in spacetime is marked by four numbers defined by a frame of reference: The 'observer' synchronizes the clocks according to their own reference frame. In special relativity, an observer will, in most cases, mean a frame of reference from which a set of objects or events are being measured. This usage differs significantly from the ordinary English meaning of the term.
Reference frames are inherently nonlocal constructs, and according to this usage of the term, it does not make sense to speak of an observer as having a location. Any specific location within the lattice is not important.
The latticework of clocks is used to determine the time and position of events taking place within the whole frame. Four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.
Understanding gravity—warps and ripples in space and time - Curious
Gravitational lensing can allow scientists to see some pretty cool things, but until recently, what they spotted around the lens has remained fairly static. However, since the light traveling around the lens takes a different path, each traveling over a different amount of time, scientists were able to observe a supernova occur four different times as it was magnified by a massive galaxy.
In another interesting observation, NASA's Kepler telescope spotted a dead star, known as a white dwarf, orbiting a red dwarf in a binary system. Although the white dwarf is more massive, it has a far smaller radius than its companion. Changes in the orbit of Mercury: The orbit of Mercury is shifting very gradually over time, due to the curvature of space-time around the massive sun.
In a few billion years, it could even collide with Earth.
How Warp Speed Works
Frame-dragging of space-time around rotating bodies: The spin of a heavy object, such as Earth, should twist and distort the space-time around it. The precisely calibrated satellite caused the axes of gyroscopes inside to drift very slightly over time, a result that coincided with Einstein's theory. GP-B confirmed two of the most profound predictions of Einstein's universe, having far-reaching implications across astrophysics research.
The electromagnetic radiation of an object is stretched out slightly inside a gravitational field. Think of the sound waves that emanate from a siren on an emergency vehicle; as the vehicle moves toward an observer, sound waves are compressed, but as it moves away, they are stretched out, or redshifted.
Known as the Doppler Effect, the same phenomena occurs with waves of light at all frequencies. Intwo physicists, Robert Pound and Glen Rebka, shot gamma-rays of radioactive iron up the side of a tower at Harvard University and found them to be minutely less than their natural frequency due to distortions caused by gravity.
Understanding gravity—warps and ripples in space and time
Violent events, such as the collision of two black holes, are thought to be able to create ripples in space-time known as gravitational waves. It is thought that such waves are embedded in the cosmic microwave background. However, further research revealed that their data was contaminated by dust in the line of sight.
LIGO spotted the first confirmed gravitational wave on September 14, The pair of instruments, based out of Louisiana and Washington, had recently been upgraded, and were in the process of being calibrated before they went online. The first detection was so large that, according to LIGO spokesperson Gabriela Gonzalez, it took the team several months of analyzation to convince themselves that it was a real signal and not a glitch.
A second signal was spotted on December 26 of the same year, and a third candidate was mentioned along with it. While the first two signals are almost definitively astrophysical—Gonzalez said there was less than one part in a million of them being something else—the third candidate has only an 85 percent probability of being a gravitational wave. Together, the two firm detections provide evidence for pairs of black holes spiraling inward and colliding.