Is time a constant?

Question

Does actual time change as the speed of light is approached, or does only measured time change?

Im not sure if it only affects how fast the clocks tick or if it changes rate at which time is moved through

Answer 1

You seem to be having metaphysical difficulties with the idea of the relativity of time.

There is no such thing as actual, absolute time. There is only measured time. If I travel at near light speed to a star and back, the journey might only take me a few years. My twin at home might have grown old and died in the interim. There is no external timekeeper that can resolve our conflict over how long the trip took. We measured different times, and we were both right.

There are mathemetical quantities upon which we can agree (like the distance of the trip squared minus the time squared). So physicists focus their attention as much as possible on these quantities (Lorentz-invariant scalars) that CAN be absolutely measured in any reference frame. Unfortunately, time and distance separately (which form the backbone of our physical intuition and Newtonian mechanics) are not such invariant quantities.

Answer 2

What is time? We define it as the rotation of the earth in relation to the sun. So to answer your question is yes it would change as you get close to the speed of the light ... your watch wouldn't change, because it is based on a constant, but your relative position with the sun would be different and therfor by our limited standards you time would change but time would also not be relevant. You would still age just as fast as you do now. Space travelers that are in between solar systems that have no sun to reference time with ... still experience the same time ... they just most likely refer to it differently. The same would be true for a planet that spins faster or slower around the sun. Their days would be longer or shorter there by effecting time as we know it.

Answer 3

Both Newton and Galileo and most people up until the 20th century thought that time was the same for everyone everywhere. This is the basis for timelines, where time is a parameter. Our modern conception of time is based on Einstein's theory of relativity, in which rates of time run differently everywhere, and space and time are merged into spacetime, where we live on a world line rather than a timeline. Thus time is part of a coordinate, in this view. Physicists believe the entire Universe and therefore time itself began about 13.7 billion years ago in the big bang.

Einstein's 1905 special relativity challenged the notion of an absolute definition for times, and could only formulate a definition of synchronization for clocks that mark a linear flow of time:

If at the point A of space there is a clock ... If there is at the point B of space there is another clock in all respects resembling the one at A ... it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. ... We assume that ...
1. If the clock at B synchronizes with the clock at A, the clock at A synchronizes with the clock at B.
2. If the clock at A synchronizes with the clock at B, and also with the clock at C, the clocks at B and C also synchronize with each other.[17]

Stylized light cone to celebrate the centennial of Einstein's annus mirabilisIn 1875, Hendrik Lorentz (1853-1928) discovered the Lorentz transformation, upon which Einstein's theory of relativity, published in 1915, is based. The Lorentz transformation states that the speed of light is constant in all inertial frames, frames with a constant velocity. Velocity is defined by space and time:

Henri Poincaré (1854-1912) noted the importance of Lorentz' transformation and popularized it. In particular, the railroad car description can be found in Science and Hypothesis,[18] which was published before Einstein's articles of 1905.

Einstein showed that if the speed of light is not changing between reference frames, space and time must be so that the moving observer will measure the same speed of light as the stationary one. Time in a moving reference frame is shown to run more slowly than in a stationary one.

Moving objects therefore experience a slower passage of time. This is known as time dilation.

One may ask which reference frame is really the moving one, since observers in both would "feel" as if they were standing still and assume the other frame is the one in motion. This gives rise to such paradoxes as the Twin paradox.

That paradox can be resolved using Einstein's General theory of relativity, which uses Riemannian geometry, geometry in accelerated, noninertial reference frames. Employing the metric tensor which describes Minkowski space.

Einstein developed a geometric solution to Lorentz's transformation that preserves Maxwell's equations. His field equations give an exact relationship between the measurements of space and time in a given region of spacetime and the energy density of that region.

Einstein's equations predict that time should be altered by the presence of gravitational fields.

Time runs slower the stronger the gravitational field, and hence acceleration, is. The predictions of time dilation are confirmed by particle acceleration experiments and cosmic ray evidence, where moving particles decay slower than their less energetic counterparts. Gravitational time dilation gives rise to the phenomenon of gravitational redshift and delays in signal travel time near massive objects such as the sun. The Global Positioning System must also adjust signals to account for this effect.

Einstein's theory was motivated by the assumption that every point in the universe can be treated as a 'center', and that correspondingly, physics must act the same in all reference frames. His simple and elegant theory shows that time is relative to an inertial frame. In an inertial frame, Newton's first law holds; it has its own local geometry, and therefore its own measurements of space and time; there is no 'universal clock'. An act of synchronization must be performed between two systems, at the least.

Dr. H

Answer 4

I think here on earth it is very constant ,as NASA spends millions to check and cross check the time between the satellite stations.

Answer 5

as einstein said, time is relative, its possible to bend time, travel through time,

he said you can travel so fast around the universe, youd come back younger than your twin sister.

Answer 6

What? the speed of light has no influence on time itself.Do u get headaches alot cause it wouldn't suprise me.

Answer 7

here's a better question, if all matter in the universe stopped moving, would time stop?

Answer 8

time is relative. not a constant

Answer 9

no one knows, there are only theories