https://www.quora.com/Is-time-the-same-as-gravity-according-to-Einstein
Newtonian
gravity is about how fast clocks are ticking. Simply put, the stronger
the Newtonian gravitation potential, the slower clocks tick there.
Other
parts of spacetime curvature also contribute, of course, but only very
little, or else the speeds involved must be very high. For instance,
when light (which can be thought of as a stream of “ultrarelativistic”
particles, moving at or near the vacuum speed of light) is deflected by
gravity, it is deflected in equal parts by time and space curvature;
hence, the deflection angle is twice what you would get using Newtonian
physics alone.
But
apart from extreme cases, “time curvature” and (Newtonian) gravity are
pretty close to being the same thing under normal, everyday
circumstances.
https://www.quora.com/How-did-Einstein-imagining-riding-a-beam-of-light-lead-him-to-the-theory-of-relativity-Is-there-a-secret-to-imagining-riding-at-the-speed-of-light-What-happens-if-I-keep-imagining-riding-at-the-speed-of-light
So,
imagining that you could travel along beside a light beam, matching its
speed, leads to an impossible situation. Therefore, it must be
impossible to travel at that speed.
The
problem is that that stationary sinusoidal field configuration contains
magnetic field with non-zero curl, and Maxwell’s equations explicitly
forbid that.
That’s all there is to it - a proof by contradiction.
https://www.quora.com/The-universe-is-expanding-faster-than-light-so-time-is-going-backward-Is-it-possible-that-the-future-of-the-universe-is-its-past
The
fact that distant parts of the universe recede from us faster than the
speed of light is a completely different animal. These regions of the
universe are said to be "causally disconnected" from ours, hidden behind
an "apparent horizon" precisely because relative to us, they're
receding faster than light... but in their own local vicinity, nothing
moves faster than light either. So causality is protected, and there are
no journeys into the past either.
So no, no matter how poetically appealing it sounds, the future of the universe is NOT its past.
https://www.quora.com/Is-the-speed-of-light-the-fastest-possible-speed-for-any-type-of-object-or-is-it-possible-for-something-to-travel-faster
Yes
I think we agree that clocks can slow down relative to other clocks.
And of course if we measure a second somewhere, whatever we measure as a
second will be a local second. All the answer says is that a local
second in one frame can last longer than a local second in another,
which is correct.
https://www.quora.com/How-do-we-know-that-we-are-not-hurtling-through-space-at-near-light-speed we are traveling at exactly light speed. (if you think in terms of 4 dimensional space-time, instead of just 3 dimensional space).
Nothing
with rest mass can move at the speed of light through space, but in 4
dimensional spacetime you are always moving because time stands still
for no one.
Even if you are standing still, you are moving at the speed of light in 4 dimensional space time!
It’s
that you and the other guy are just disagreeing about what counts as
stationary. Each of you has a clock and that clock measures time in that
rest frame. A rest frame is one that’s moving only in the future time
direction.
https://www.quora.com/If-time-slows-down-at-high-speeds-high-speeds-relative-to-what
And the straightest path, i.e. shortest distance, is the path of
greatest proper time. So you have to keep in mind two kinds of time. One
is coordinate time, which is just a label we can put on events, the
same way we put a longitude and latitude on them. The other is physical
time which is duration along a path, the way we talk about the distance
between points depending on the roads we take.
https://www.quora.com/Whats-so-challenging-about-accepting-that-time-can-move-at-different-speeds-and-how-can-we-explain-it-without-all-the-complex-math
it [relativity] just uses a tool for managing passing time in which we treat time as a dimension of space....We
account for entropy through statistics … this produces an asymmetry in
the time axis that does not usually exist in the space ones....psychological arrow of time points in the direction of increasing entropy. That doesn’t conflict with general relativity at all.
https://www.quora.com/According-to-general-relativity-theres-no-such-a-thing-as-time-On-the-other-hand-entropy-seems-to-be-a-timeline-so-how-do-both-concepts-get-unified
A
photon does have infinite speed from a certain point of view. That
would be its own view. Since ZERO time elapses no matter the distance it
covers you could say that is infinite speed. However since the distance
it travels in the direction it is headed is only two dimensional it has
covered no distance at all.... So speed is just the wrong scale to consider here - you need to consider energy or momentum.
This
isn’t a trick - it’s always the case that you can turn infinite scales
into finite scales and vice versa. The math behind it is called
“conformal transformation.” The physicist Roger Penrose has a way of
drawing a picture of the entire infinite universe on a finite piece of
paper. It’s called a Penrose diagram,...So
you can think of “speed” as a conformal transformation of an
energy/momentum scale. Speed is like the “on diagram” distance in a
Penrose diagram - it “runs out” within the finite page. And speed “runs
out” at c.
- There's proper velocity, which is a measure of how far the light moves for every second that passes for it.
- There's time dilation, which is a measure of how much the light advances into the future for every second that passes for it.
- There's rapidity, which is analogous to an angle; but it's an angle between space and time.
The only measure that's finite is classic velocity, the ratio of proper velocity to time dilation.
dτ is the time-like separation between two events (points
in spacetime identified by when and where they are). In the same way
that the collection of all points in space with the same dr forms a circle, the collection of all events in spacetime with the same dτ
forms a hyperbola.
This notion of proper time is an important one in Relativity, because it's an invariant quantity: no
matter what frame of reference you use (in effect, the choice of valid
coordinate systems), the separation between two events dτ
will always be the same. This is similar to how the distance between
two points is always the same no matter how much you spin around...The equation for proper time is dτ2=dt2‐(dr/c)2.
That use of a minus instead of a plus is what makes all the difference,
as that changes it from an equation of a circle to the equation of a
hyperbola. (The c in the equation is a spacetime conversion factor, saying in effect that there are 299,792,458 meters in a second.)...Any finite amount of “rotation” will fall short of a true diagonal, because the change in dr/c will always be slightly less than the change in dt; and infinite “rotation” will exactly reach that diagonal, where dr/c=dt....the ratio between them approaches a finite limit. That ratio is what we traditionally call speed: a change in distance (dr/c) over a change in time (dt).https://sciencefringeareas.quora.com/If-light-has-no-mass-then-the-speed-of-light-should-be-infinite-Why-does-light-have-finite-speed
Photons (and anything traveling at “c”) do not have a reference frame
*at all*. This is a consequence of the definition of the invariant speed
and of a rest reference frame. It is fairly simple.
- Anything that travels at the invariant speed “c” travels at that speed in ALL reference frames.
- A rest reference frame is one in which the object is at rest (traveling with 0 velocity) relative to itself.
- If
an object travels at the invariant speed “c” then in must travel at
that speed in ALL reference frames, including its own rest reference
frame.
the concept of time for an object traveling at light speed becomes
meaningless. This is because, according to relativity, as an object's
velocity approaches the speed of light, time dilation increases without
bound. At light speed, the equations that describe time dilation lead to
undefined results, indicating that the passage of time cannot be
defined for such an object.
Light
has mass in the sense that it contains a quantity of energy, but it is
not referred to as mass when it travels freely at c. If that energy is
absorbed by matter, it then shows up as additional mass. Whenever energy
is bound up in things that collectively travel at less than c, all of
that energy becomes classed as mass, but if you break the object up and
turn it entirely into electromagnetic radiation that shoots off in
multiple directions at c, none of that energy is called mass.
https://www.quora.com/Why-do-scientists-state-that-once-the-speed-of-light-is-reached-the-time-stops-Is-it-a-true-fact-or-just-a-theory
You’
never see ‘your’ time slow down. ‘You’ always see things as if ‘you’
are at rest. Other things are always moving relative to (stationary)
‘you’....I
meant from the POV of an observer, who was overseeing both events
simultaneously. They'd see light in both frames (of reference) travel at
c, and the events in each frame would be observed to pass more slowly
than if observing a,stationary frame.
https://www.quora.com/If-you-are-travelling-at-nearly-the-speed-of-light-how-fast-is-light-travelling-away-from-you
yes this is very much how “you” is defined as an “external observation.” Louis de Broglie’s Law of Phase Harmony was a critique of relativity from the perspective of quantum physics. de Broglie called the Law of Phase Harmony his “greatest discovery” and he has a Nobel Prize yet his “Law of Phase Harmony” is not taught in physics classes! Why? Well Bell’s Inequality that got the Nobel Prize and disproved Einstein is still misunderstood by other Nobel Prize physicists as Professor Jean Bricmont has detailed so well. Quantum physics professor Basil J. Hiley who had collaborated with David Bohm, who confirmed the Law of Phase Harmony, tried to explain to Nobel physicist Roger Penrose that indeed it is noncommutativity as nonlocality that is the secret of the foundation of reality in quantum biology. I have a paper on this secret - it’s based on listening as logical inference - NOT an external visual observation as the definition of the I or Self. see the academic journal “Cosmos and History” - peer-reviewed, open access Dec. 2024 issue for “noncommutativity music as biophysics” article. You can also read Nobel physicist Gerard ’t Hooft’s article “Light is Heavy” for a good start.
If
two objects in inertial frames are moving in relation to one another
and yet both measure light as traveling at the same speed, that means
that the relative movement of one MUST be causing distortions in space
and time (the components of speed) in the frame of the other. At the
speed of light, those distortions are so great that space is contracted
to 0 and time dilated to infinity. Something moving at the speed of
light carries the most possible distortion it can create in the
observer's frame while still having a meaningful existence.
https://www.quora.com/Whats-the-fundamental-reason-why-the-speed-of-light-cannot-be-broken-Why-does-the-universe-want-to-preserve-the-upper-barrier-on-speed-of-light-so-much-so-that-it-readily-slows-down-time-rather-than-see-the-speed-barrier-broken
light
is just one example of something that moves at this speed, and the
reason it does is because it has no mass. Gravity also moves at the same
speed. Anything with no mass must move at the special speed in the eyes of any observer.
https://www.quora.com/What-makes-the-speed-of-light-unique-in-terms-of-measurement-in-space-and-time-Are-there-other-methods-of-measuring-these-concepts
AI:
Noncommutativity can violate invariance
because it introduces a dependence on the order of operations,
which breaks symmetries like Lorentz invariance in physical theories.
In many standard theories, the order of operations does not matter,
meaning the result is the same regardless of the sequence (this is the
commutative property). However, in a noncommutative theory, this is not
true, leading to consequences like the violation of fundamental
symmetries, such as the conservation of energy-momentum, which is linked
to translational invariance
.....................
you (and your reference frame and clock) are always moving at the speed
of light through spacetime, and what you think of as stationary is
really moving in the time only direction....so
that now, *relative* to the former stationary state, you are moving
thru space too. But you’re moving less thru time, your clock runs slower
*relative* to a clock left in the frame we called stationary,
Galileo
illustrated the relativity of motion by noting that the motion of a
boat drifting down a placid river was undetectable below decks in the
boat.
https://www.quora.com/Can-you-explain-simply-why-time-slows-as-you-move-faster
proper
time may imply a different amount of time measured along some
space-time path — which is one of the deepest answers to the so-called
twin paradox — but it says nothing about the rate of passage, as it is
called.
https://sciencephysicsmath.quora.com/In-simple-terms-why-does-time-slow-down-as-you-travel-closer-to-the-speed-of-light
More importantly, Pythagoras’s theorem is different in space-time. In normal space, we can say C2=A2+B2
and it then follows that the shortest distance between two points is a
straight line. In space-time, the equivalent equation (using only one
spatial dimension for simplicity) is s2=x2−(ct)2
and the minus sign has serious counter-intuitive consequences, such as a
straight path between two points actually maximising the proper time
(i.e. the time as would be experienced, or measured, on such a path).
What
this means is that any irregular (non-straight) path for one twin —
whether it is a simple turnaround or a series of random accelerations
and decelerations — will mean that the proper time for that path will be
less than the one for something travelling at a steady constant
velocity (i.e. a straight world-line in space-time). The other
explanations are simply special cases of this. ...
The age discrepancy arises from the different space-time paths that
they take. When they meet at some given space-time location then they
will see the difference.
If
two people simply walked different paths to get to a common meeting
point, they could compare their routes and one might notice that they
had used more shoe leather. This is similar only insomuch as they become
aware when they meet, and not before. Neither has experienced time at a
faster or slower rate — merely a different amount of it........
The
complication is because the rotating twin’s constantly changing
inertial frame can be said to have a speed relative to the other twin. I
suspect that the ageing difference would be visible to them — good
question!...........
if
you count ticks of clocks, one at rest and the other three moving fast
in three perpendicular directions (as seen by the stationary clock),
together with one for each pair as above, and square those counts, you
obtain uniquely a quadratic form. It’s then an experimental fact that
this quadratic form counts the squares of clock ticks on all clocks. In
particular it makes no difference which clocks to use to measure it.
And
it’s nondegenerate. So the orthogonal complement of the clock is three
dimensional. It’s also an experimental fact that on the orthogonal
complement this quadratic form is negative definite, so it’s minus a
Pythagorean metric, and that this Euclidean space is in fact “space”, as
experienced by that clock.
That’s the essential physical content.
If you understand this much, the rest is working out the mathematical consequences of the model.
https://www.quora.com/Why-is-Einsteins-theory-of-relativity-considered-difficult-to-understand-even-for-physicists-Can-you-explain-why-it-may-not-make-sense-to-some-people
In
spacetime, two observers in different reference frames can no longer
agree on “now.” Neither can they agree on “when.” “Now” for one observer
might be the past for the other. Clocks do not tick at the same rate in
spacetime. The distance from one place to another and the time it takes
to get there is malleable. Straight lines are no longer straight and
gravity is a pseudo-force caused by curvature in the presence of matter.
There may be places in the universe where the passage of time no longer
has any meaning and the known laws of physics break down.
But
don’t get too comfortable with spacetime. Like all models, it has
limits. Some of the math used in Einstein’s theory break down under
extreme conditions like black holes or at the big bang. Solving that
conundrum and unifying Relativity with Quantum Mechanics is the next
holy grail of physics.
https://www.quora.com/What-is-spacetime-8
Relativity
says that there is a universal “now”, but it is impossible for me to
verify the conditions of now at another place without getting a signal
from there or to travel there. But both of them takes time and by the
time I get that information, time will pass and things change by the
time I verify them. I see the sun the way it was 8 minutes ago not the
way it is now.
Physical
processes happen all over the universe at a certain rate. There is such
a thing as psychological experience of time and it is the result of
remembering how things used to be and seeing the difference between that
and how they are now. “My room was organized and now it’s messy” gives
me the sensation of time passing.
But
to have a quantitative sensation of time we need time measuring devices
with an accurate rate. That can be moon cycles, seasons, sun dials,
hour glasses and clocks.
Spacetime
is a concept of imagining a tiny clock at every single point in space
that measures the local time at that particular point. But this is just a
model because obviously there is no clock at every single point in
space.
Special
relativity’s idealized spacetime model says that without mass all these
clock are and remain synchronized all the time. This is not true
because there is gravity everywhere and the clocks do get out of synch.
But general relativity deals with that.
https://www.quora.com/Why-is-spacetime-curved
“Time
curvature” affects the rate of clocks. As a general rule, in a
gravitational field, clocks tick slower than elsewhere. This effect is
primarily responsible for gravity. All other effects, including space
curvature, contribute only a tiny, tiny correction except in the
presence of extremely strong gravitational fields (surface of a neutron
star, immediate vicinity of a black hole.)
https://www.quora.com/What-is-space-curvature-as-opposed-to-time-curvature-really
- :
for something moving at the vacuum speed of light, spatial curvature
and time curvature contribute equally, doubling the effect of gravity on
their trajectories.
To wit: Time curvature affects clocks; space curvature changes geometry.
