I Gravity Wave Propagation: Negative Energy Pulse?

desertsoldier39
Messages
2
Reaction score
0
TL;DR Summary
First year Astronomy and planetary sciences student. Have some questions when looking at G-wave propagation and formation simulations.
At 0:51 in this simulation video there seems to be a brief moment upon merging that these singularities produce what appears to be negative gravitational "Spike?" that seems to bulge spacetime in an opposite metric compared to normal spacetime flatness. Is this a quirk of the simulation or is this a pulse of negative energy?

 
Physics news on Phys.org
I also have a second question above G-waves themselves. They appear to be propagating waves of contracting and expanding spacetime. When spacetime contracts at the leading edge of the wave and then expands, does the expansion revert back to normal spacetime flatness or is there a momentary expansion beyond that metric?
 
First, nomenclature: it is gravitational waves, not gravity waves. Gravity waves are things like waves on a water surface.

Second, you cannot really learn much about gravitational waves by watching simulations like this, which will always be some lower dimensional representation of the full simulation.

It is not clear to me what you would mean by ”opposite metric”. The metric of a spacetime is by construction Lorentzian everywhere.

In particular coordinate systems, gravitational waves may be described as space expanding and contracting (not spacetime, which is what it is - time is a part of it so it does not actually do anything). However, that is a coordinate dependent interpretation requiring you to make particular choices of coordinates and assign them the space and time labels.

desertsoldier39 said:
When spacetime contracts at the leading edge of the wave and then expands, does the expansion revert back to normal spacetime flatness or is there a momentary expansion beyond that metric?
This completely depends on the shape of the wave - as for any wave, gravitational waves are governed by the wave equation.
 
  • Like
Likes vanhees71
In this video I can see a person walking around lines of curvature on a sphere with an arrow strapped to his waist. His task is to keep the arrow pointed in the same direction How does he do this ? Does he use a reference point like the stars? (that only move very slowly) If that is how he keeps the arrow pointing in the same direction, is that equivalent to saying that he orients the arrow wrt the 3d space that the sphere is embedded in? So ,although one refers to intrinsic curvature...
So, to calculate a proper time of a worldline in SR using an inertial frame is quite easy. But I struggled a bit using a "rotating frame metric" and now I'm not sure whether I'll do it right. Couls someone point me in the right direction? "What have you tried?" Well, trying to help truly absolute layppl with some variation of a "Circular Twin Paradox" not using an inertial frame of reference for whatevere reason. I thought it would be a bit of a challenge so I made a derivation or...
I started reading a National Geographic article related to the Big Bang. It starts these statements: Gazing up at the stars at night, it’s easy to imagine that space goes on forever. But cosmologists know that the universe actually has limits. First, their best models indicate that space and time had a beginning, a subatomic point called a singularity. This point of intense heat and density rapidly ballooned outward. My first reaction was that this is a layman's approximation to...
Back
Top