What i meant is that space-time is abstract. In relativity, we make extensive use of metric tensors. A tensor is a generalization of a vector to higher dimensions. Vectors have both magnitude and direction. In QFT spinors are used instead of tensors.
In general relativity, metric spaces...
Shadows and light spots can go faster than light but they can't carry physical information. This is confirmed by many experiments, including the spot of a laser which is pointed at the surface of the moon.
This can also be confirmed using logic. Distance and direction are abstract and...
Where is the valid experimental argumentation for space-time, time travel etc?
First of all velocity is a vector and a vector has both magnitude and direction but distance & direction are both abstract (non-physical).
Then you understand that gravity has nothing to do with the curvature...
Causality says that every effect must have a cause (e.g, energy is needed to do work). What we have (and what we are of course) is a proof that causality is never violated.
Like i said, the velocity 4-vector is not a physical velocity. I guess we just have to agree to disagree.
You are wrong. What the guy said is that space-time is a mathematical construct and he's definitely not wrong about that. There's no time axis, it's abstract (non-physical).
Do you...
It's possible to define a 4-vector in special relativity but it's not a physical velocity:
g_{\mu\nu}\eta^{\mu}\eta_{\mu} = \gamma^2 c^2 (1-\frac{v^2}{c^2}) = c^2
If you don't believe in time travel then why are you are arguing with me?
Particle physics says that there are only...
And he almost surely understands it better than you. Relativity does not allow motion in space-time. Why not? Because time is an abstract invariant.
It remains to be seen whether time travel is possible, as you say it is.
How can you say that something is possible if the physical...
Sorry and we could care less about you write. What he writes is not only logical but is also supported by evidence from real life. 4-velocity is not even a physical velocity so why do we call it velocity.
There is no evidence for the physical existence of spacetime and definitely not for...
Few physicists know the complex math of general relativity. What is meant with time-travel? Does this mean that we can run the movie backwards? Can we go back to the stone age?
Anyway, here is a very good argument against time travel.
http://mb-soft.com/public/time.html
Time travel...
What is the difference between v = \frac{dt}{dt} and v = \frac{dt}{d\tau}?
Proper time is time measured when the clock is at rest relative to the observer.
d\tau = \frac{dt}{\gamma}
or
d\tau = dt\sqrt{1-[\frac{v(t)}{c}]^{2}}
He writes that tau is also an invariant evolution...
I'm also working on a theory to combine gravity with magnetism.
I think that the CMBR is not the redshifted photons from the big bang. It's the electromagnetic fields of the quantum vacuum (the ground state of the quantum vaccum). If the sun is charged it really solves the puzzle.
Few physicists know relativity and AFAIK relativity does not allow for time travel. Motion in space-time is itself impossible (by definition). If you are serious about this, then i really doubt the correctness of the theory.
By far the majority of physicists consider time travel as pseudoscience. There just isn't any experimental evidence that it happens.
Relativity does not allow motion is space-time. It allows motion in space. Time is just the abstract inverse of change. Change (or motion) is primary, time is...
Once we postulate the physical existence of a time axis, motion immediately becomes an impossibility.
http://arxiv.org/PS_cache/gr-qc/pdf/0503/0503097.pdf [Broken]
General relativity did not past all tests. Dark matter has never been detected or produced experimentally. Another problem with GR is infinite space-time curvature and the rapid expansion of space (from a singularity). Could you please tell us where all this energy is coming from?
Sean M...
Newton's first law states that a body at rest will remain at rest and a body in motion will continue in motion with constant speed in a straight line, as long as no unbalanced force acts on it.
So does that mean that motion is acausal? Do bodies stay in motion for no reason at all? If a...
GR did not pass all tests. Also these tests were indirect tests. Physics is not math. Math does not explain physical phenomena.
Science rests on it's philosophical foundations. The philosophy of space-time goes back Gottfried Leibniz, not to Popper. Leibniz rejected the physical existence of...
I agree with sd01g. Space-time is an abstract mathematical construct. It's not physical.
Time dilation & time travel is also impossible. Time is an abstract invariant by definition. Time doesn't really slow down. It's the clocks (including our internal clock - the heart) which slow down due...
I also think that the real question is what causes our abstract spacetime to curve in the first place. The problem with time expanding is that time is an abstract invariant by definition. Since time is abstract, it's physically meaningless. The real focus here is motion, not time.
Einstein's equations allow the possibility of time dilation and time travel, which is a contradiction because time is an invariant by definition. There is no dynamics in the time axis, otherwise nothing could move and we get a block universe.
General relativity allows movement in space, not...
I think that the real difference between quantum mechanics and general relativity is that quantum mechanics is not only abstract but also deals with the interactions of absolute particles.
Also quantum mechanics rejects the existence of physical space, existing seperately from absolute...
It is philosophical. The philosophy of space-time goes back to Gottfried Leibniz. Can physical space exist separately from matter? If the answer is no then the relative is abstract and depends on the absolute.
If space is the absence of mass-energy (which are absolute), then how do we know it exists physically (with no observer)? Also is it possible that time does not dilate (isn't time invariant by definition?) but the clocks slow down due to energy conservation principles at work?
I am totally...
From the complex point of view, the porpuse is to investigate in more general terms the character of transforms for which the mapping function w = u(x,y) + i\nu(x,y) is analytic.
Since w = f(z) is analytic, substituting into the jacobian determinant, we get
J \left ( \frac{u,\nu}{x,y}...
There is another one by John Pain. There is not much you need to know except sound (or mechanical waves) and electromagnetic waves.
PS: And of course partial differential equations.