Roberto Pavani's latest activity
-
Roberto Pavani reacted to Matterwave's post in the thread Undergrad Could future technology test what lies beyond the observable universe? with
Like.
Are you talking to me? Note this sentence in my post #25: Try your integral but this time use an actual cosmological constant. What... -
Roberto Pavani replied to the thread Undergrad Could future technology test what lies beyond the observable universe?.My fault. I didn't realize you meant a constant "cosmological constant".
-
Roberto Pavani replied to the thread Undergrad Could future technology test what lies beyond the observable universe?.Doesn't this requires that ## \int_{t_0}^{\infty}\frac{dt}{a(t)} ## to be finite ? Acceleration itself doesn't allow this. As an...
-
Roberto Pavani reacted to Jaime Rudas's post in the thread Undergrad Could future technology test what lies beyond the observable universe? with Like.
For the sake of clarity regarding terms: The particle horizon is the current distance to the farthest comoving object from which, in...
-
Roberto Pavani reacted to PeterDonis's post in the thread Graduate Can exact Lorentzian kinematics emerge from Euclidean space? with Like.
Proper time can't be a coordinate, because different observers that follow different worldlines between the same two events can have...
-
Roberto Pavani replied to the thread Graduate Can exact Lorentzian kinematics emerge from Euclidean space?.Strongly agree
-
Roberto Pavani replied to the thread Undergrad Problem in understanding how upwards acceleration works (General Relativity).Yes, we can Note: acceleration is ## \approx 9.81 \frac m { s^2 } ## because ## g \propto \frac 1 { R^2 } ##
-
Roberto Pavani replied to the thread Undergrad Problem in understanding how upwards acceleration works (General Relativity).V = 0 doesn't matter. Throw C upward: at the top ## v=0 ## for an instant, but C ir's still free-falling all the time (accelerometer =...
-
Roberto Pavani replied to the thread Undergrad Problem in understanding how upwards acceleration works (General Relativity).I never specified the height where the stones are, A can be on the ground, while B and C on the rooftop with C falling from there. In...
-
Roberto Pavani replied to the thread Undergrad Problem in understanding how upwards acceleration works (General Relativity).You have to specify the reference frame to define motion, that's the key. Here perhaps a too simple explanation: Three stones: A and B...
-
Roberto Pavani replied to the thread Graduate Can exact Lorentzian kinematics emerge from Euclidean space?.I think the two spaces have to be kept separate, like Fourier space vs the function space the transform acts on. Then you can set up a...
-
Roberto Pavani replied to the thread Graduate Can exact Lorentzian kinematics emerge from Euclidean space?.Only if you solve the problem of time, as PeterDonis pointed out, in R4 you have four spatial directions and no time. Some related...
-
Roberto Pavani replied to the thread Graduate Are mass, particles, and fields fundamental?.That's a good question. Within the Standard Model, fields are simply part of the starting assumptions of the theory; they are not...
-
Roberto Pavani reacted to renormalize's post in the thread Graduate Are mass, particles, and fields fundamental? with Like.
What is the "mass" that "makes", for example, the electromagnetic field? Please be specific.
-
Roberto Pavani replied to the thread Graduate Are mass, particles, and fields fundamental?.I don't think it is correct to say that particles and fields are made of mass. In the Standard Model, fields are the fundamental...