So special relativity says that relative distances locally can't be changing at a rate greater than c? Does this mean that, in a fundamental sense, recessional vs. approaching velocities have nothing to do with it? Does this leave open the possibility, if there were just the right spacetime...
Doesn't "dark energy" or the scale-factor expansion of the universe change the whole ball game regarding whether "faster than light" travel is possible, at least in terms of recessional velocities?
Hear me out: I understand that if we disregarded scale-factor expansion, then a rocket could...
Consider a far-away galaxy that is considered to be currently receding from Earth at 2x the speed of light. (With this 2x c recession velocity, we are speaking of the Vnow, the imputed relative velocity of the galaxy compared to Earth now, not the velocity of the galaxy relative to Earth at the...
That was very helpful, PeterDonis! And I understand that, to truly understand this stuff, I would need to understand the math. But you did a pretty good job of creating the sort of metaphors I was looking for!
I just have one final question: from what I have seen of the "Mexican hat" graph...
But I still don't understand...wouldn't you want to use the decomposition when h is large? When you don't use the decomposition, are you just treating the energy of the Higgs field at that point as if it is H0 and just throwing away whatever h would be (in which case this would be most...
Thank you for your response! Although I don't think I really understood your post. It sounds to me like you are saying that, when energies from sources other than the Higgs field are very high, they dwarf the effect of the Higgs field by comparison and make the calculation of that minor...
Hi all,
I was reading about the history of the early universe today, and there were some things that I did not understand. In particular, I do not understand the concept of "spontaneous symmetry breaking." After reading the Mexican Hat analogy many times, here is my best understanding of it...
"If the entire universe were to accelerate rotationally, with you at the center of rotation, you would feel the effects the same as if your spaceship were spinning around. You and everything inside would be pushed to the walls by a “fictitious” force, and hence you would feel proper acceleration...
Ah, so it has to do with weight. Thanks for the explanations, it makes sense!
So, in the twin paradox experiment, the twins start out inertial, which relative motion between each other of 0 km/sec. When the experiment begins and one is on a non-firing rocket and the other is on a rocket that...
Earlier today I was reading through this entire thread:
https://www.physicsforums.com/threads/implications-of-the-statement-acceleration-is-not-relative.670653/
And I remained confused about one thing in particular. The original poster made a statement (bolded below) on page 1 that seemed...
Here's a thought-experiment that really has me stumped:
Imagine an Earth/moon system in isolation from the rest of the universe. No other matter or energy exists.
From the moon's vantage point, would it not be reasonable to conclude that the moon is stationary and not spinning, and that the...