Weird physics question - relativistic immobility

[KrazyHorse]

I can accelerate at 1G forever and my velocity in my own reference frame remains 0.

Your reference frame is invalid in the context of special relativity.

[KrazyHorse]

Is there any reason that you think that a beam of light's own reference frame is an invalid one, siro? What is the velocity of this beam of light in its own reference frame? What is the velocity of all other objects in the universe in this frame?

[Sirotnikov]

I can accelerate at 1G forever and my velocity in my own reference frame remains 0.

Yes, but you'd still feel the effect of acceleration (= Force), even if your velocity is 0.

The key observation that leads to special relativity is that if you are moving at the speed of light relative to one reference frame, you are moving at the speed of light relative to all reference frames.

which is what 'regardless of frame of reference' meant to say.

[KrazyHorse]

Come on, kuci: what does having data arranged in isolatitudes have to do with spherical harmonics and thus the CMB? This is largely a computational question...

[Sirotnikov]

I've yet to study general relativity. How does acceleration being relative settle with acceleration being compared to an action of a force?

In the twins paradox, a twin speeding through space at the speed of light and then changing direction and returning to earth, would feel the effect of acceleration, even though in his frame of reference his velocity was 0, and therefore technically have an acceleration of 0.

[Sirotnikov]

Is there any reason that you think that a beam of light's own reference frame is an invalid one, siro?

Haven't thought about it well enough?

Huge C / C++ projects caused me to skip a third of my physics classes.

[Sirotnikov]

If this thread helps me pass my approaching physics exam, this would be the first time poly hasn't been a bad influence on my studies.

[Ben Kenobi]

bonus points to any amateur astro people who can, without looking it up, figure out why the isolatitude part is really important.

4 dimensions, time + xyz?

I've had to do some spherical projections, real pain in the ass.

[Ben Kenobi]

"Accelerate to near the speed of light" implicitly is "relative to the Earth".

Uh, no. c is a constant.

Say if I'm driving towards you at 0.5 c and another vehicle is driving towards me at 0.5, the light sent from him appears to travel at c.

[Ben Kenobi]

How does acceleration being relative settle with acceleration being compared to an action of a force?

The acceleration doesn't change. The mass changes. At velocities closer to c, the relativistic mass increases exponentially. This is why you need greater force to maintain constant acceleration. Technically, you would need greater force to move any object as the velocity increases, but the relativistic mass term is so small that it's the same as F= ma.

[Kuciwalker]

Come on, kuci: what does having data arranged in isolatitudes have to do with spherical harmonics and thus the CMB? This is largely a computational question...

I'm not an astro person I don't know what "hierarchical equal area isolatitude" means and you said not to look itup

/just looked up HEALpix

Spherical harmonics are, IIRC, just the equations for standing waves on a sphere.

Honstly, I'm not sure. Is it that the isolatitude bit means the pixels (at sufficient resolution) correspond to the wavelength of any standing waves?

[Kuciwalker]

Uh, no. c is a constant.

Say if I'm driving towards you at 0.5 c and another vehicle is driving towards me at 0.5, the light sent from him appears to travel at c.

Dude, I know more physics than you do. Stop embarrassing yourself. Your response doesn't even make sense in context.

[Kuciwalker]

In special relativity, acceleration is not relative. In general relativity it is

I know. That wasn't relevant to the specific point at hand, though.

[KrazyHorse]

I've yet to study general relativity. How does acceleration being relative settle with acceleration being compared to an action of a force?

Gravitation is not a force in the sense you're thinking of it in GR.

Acceleration is relative to the local curvature of spacetime

[KrazyHorse]

Honstly, I'm not sure. Is it that the isolatitude bit means the pixels (at sufficient resolution) correspond to the wavelength of any standing waves?

Isolatitude means what it sounds like: that lines of latitude run through large numbers of (the centers) of pixels.

In other words, I'll have a bunch of pixels centered at latitude a, then a bunch at latitude b, etc. etc.

If I just tesselated the sphere without thinking too hard then there's no reason that I'd end up with this arrangement. I'd end up with one at latitude a, one at latitude b etc.

Why is the behaviour of isolatitude tesselations nice in the context of spherical harmonics?