171–180 of 245 posts
Lorentz transformations are never going to length-contract the underlying fabric of space/spacetime. Relativistic length contractions contract moving objects, not the underlying spacetime.
In fact it's a strange and basic misunderstanding to have.
Now about the string theory / quantum gravity furore, after decades of work by arguably extremely bright people its pretty clear that Nature in the current juncture is not giving us enough clues to proceed. This should not be stressful - Nature is not a Hollywood production studio that needs to churn gee-wow "experiences" every season. But Sayre's law applies rather well [1] "In any dispute the intensity of feeling is inversely proportional to the value of the issues at stake.". What is at stake here is the ego of a few individuals that assumed otherwise (i.e., that a post-Einstein revolution is imminent) and the (relatively minor in the scheme of things) research funding of this particular niche of physics.
Theoretical physics is not the only domain bouncing regularly between "hypes" and "winters", as the recent Nobel prize for Physics clearly demonstrates.
Sabine is often right, but I think she's wrong here about Lorentz invariance being a problem, or at least a problem in the way she's saying. Lorentz transformations are never going to length-contract the underlying fabric of space/spacetime. Relativistic length contractions contract moving objects, not the underlying spacetime. In fact it's a strange and basic misunderstanding to have.
Sabine is often right, but I think she's wrong here about Lorentz invariance being a problem, or at least a problem in the way she's saying. Lorentz transformations are never going to length-contract the underlying fabric of space/spacetime. Relativistic length contractions contract moving objects, not the underlying spacetime. In fact it's a strange and basic misunderstanding to have.
Sabine is often right, but I think she's wrong here about Lorentz invariance being a problem, or at least a problem in the way she's saying. Lorentz transformations are never going to length-contract the underlying fabric of space/spacetime. Relativistic length contractions contract moving objects, not the underlying spacetime. In fact it's a strange and basic misunderstanding to have.
Depending on your reference coordinate system, space is transformed. That is the entire point of relativity theory. You might be misunderstanding things here.
The fundamental reason for this is simple. Humans are prone to cognitive dissonance. Meaning, we do absurd things to avoid painful thoughts. And anything that questions our sense of identity, is a painful thought. So if my self-image is, "I've advanced our understanding of the fundamental nature of reality," then the idea that my contributions weren't useful becomes painful. So we avoid thinking it, challenge people…
There’s a lot of prestige and grant money that comes with insisting climate change is true.
There’s a lot of political power that gets ceded to the people in charge if we “just accept that we’re in a crisis and us elite are the only ones that can stop it”.
I believe climate change is real and human caused, but many of the claims and doomsday speak feel like self interested humans following their incentives beyond the scientific truth
If LQG turns out to be unworkable, we're back at string theory as the only renomalizable description of quantum gravity. Quantum gravity research amounts to one professor per university faculty on average. Even in the worst case this would not be the crisis of unmet expectations it is made out to be... QG researchers are very brave because they are risking everything on the possibility that existing data constrains q…
I think you mean, we're back at "we're not sure if string theory is a viable theory of anything real".
Quantized gravity is not necessarily the right answer, and an insistence on this fundamental assumption might be the origin of these difficulties, eg. see Oppenheim's semi-classical gravity.
Sabine is often right, but I think she's wrong here about Lorentz invariance being a problem, or at least a problem in the way she's saying. Lorentz transformations are never going to length-contract the underlying fabric of space/spacetime. Relativistic length contractions contract moving objects, not the underlying spacetime. In fact it's a strange and basic misunderstanding to have.
Sabine is correct. All objects in a spacetime are anchored to that spacetime, so if spacetime has a minimum length, then length contraction of moving objects has a detectable lower limit, thus violating Lorentz invariance.
it's true that a sufficiently fast moving object would be length contracted so much that it started interacting with the minimal LQG length, which would violate Lorentz invariance. Depending on how big the LQG loops are, that could be a fanstastically high speed that isn't achievable in the universe though.
If you want to reply to https://news.ycombinator.com/item?id=41811140 or say something Sabine-adjacent, please do it here. (This is so https://news.ycombinator.com/item?id=41808143 doesn't get too offtopic)
she said some outlandish stuff in one video - I don't remember which. I refuse to watch any more of her videos.
Earlier quoted context omitted.
Sabine is correct. All objects in a spacetime are anchored to that spacetime, so if spacetime has a minimum length, then length contraction of moving objects has a detectable lower limit, thus violating Lorentz invariance.
She seems to be talking about spacetime itself being Lorentz contracted though. it's true that a sufficiently fast moving object would be length contracted so much that it started interacting with the minimal LQG length, which would violate Lorentz invariance. Depending on how big the LQG loops are, that could be a fanstastically high speed that isn't achievable in the universe though.
I assume the paper she and Brian Keating are talking about were very explicit in how they tested this property and how Lorentz invariance was expected to be violated, so you could check the paper for specifics.