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seen Apr 9 at 4:57

I am a physicist,


Mar
24
comment Rigid body collision, 3 circles in contact
But let me think more about it.
Mar
24
comment Rigid body collision, 3 circles in contact
But in that case the balls are already in contact, it is not what I meant by "simultaneous" collision. It is a more complex interaction that can be "simplified" into a "simultaneous" collision. If you are going to simulate such configurations I guess you cannot use a "non-simultaneous" approach.
Mar
6
comment Where is the atmospheric pressure equal to zero?
"any points in the same horizontal line should have the same pressure" is only valid within the same medium if you do not cross any interfaces
Mar
6
comment How do we demonstrate that all spectral colors exist in nature?
I mean whatever is the minimum amount of detail that can be observed with the better spectrometer. That is, the frequency difference that corresponds to two adjacent pixels in a spectrum (but I do not know how much that amount currently is).
Mar
6
comment Where is the atmospheric pressure equal to zero?
I would not call "atmospheric" the pressure at A. It is not in contact with the atmosphere and as DavePhd said, you can approximate it as being a vacuum (that is why you assume is zero).
Mar
5
comment Are particles solid?
Danu, dot get angry, I will erase my earlier comment on your answer, I was drunk. Deal?
Mar
5
comment Are particles solid?
I mean "if". I corrected it thanks. What I meant is that if space itself is made of "units", or quanta, so that there could be nothing smaller than these units.
Mar
5
comment Intuition behind Faraday's Law?
Unfortunately, in many cases, understanding the physics implies understanding the math. In many cases you cannot make things simpler (but it might be that someone comes up with an intuitive explanation that doesn't requires to understand the math. I just cannot figure it out)
Mar
5
comment Intuition behind Faraday's Law?
it is not that obvious, at least to me. You would rather need to use the Maxwell–Faraday equation, which is a generalization of Faraday's law. You can get more details (if you can follow the math) at the link you origianally provided: en.wikipedia.org/wiki/…
Mar
5
comment Intuition behind Faraday's Law?
I might have misinterpreted your question. You are right that Faradys law can be explained (if you know maxwell' equations) by the fact that a changing magnetic field produces an electric force. But you could not derive that from basic principles at Faraday's time. The fact that a changing magnetic field does generate an electric force is an experimental observation (new at that time), it doesn't have to be so.
Aug
15
comment A thought experiment on vision and curved spacetime
no, the lines will look straight, it is just that the grid will not look like made of squares but of some other trapezoidal shape (if the curvature is large enough for this to be perceived. The answer to the other issue will take longer and there are different ways to do it. You should ask that as a separate question.
Apr
22
comment Robot controling pouring process from a bottle
it is a very complex problem involving turbulence, unless you can make the robot to start pouring slow enough at the beginning (but it might not help). My suggestion, is unless your thesis requires to use fluid mechanics, use some easier algorithm based of feedback instead, it will be simpler and closer to what a human do.
Apr
17
comment Paradox with Gauss' law when space is uniformly charged everywhere
thanks, now I've got it!
Apr
17
comment Paradox with Gauss' law when space is uniformly charged everywhere
I agree with you that it is "physically" impossible, or at least dependent on the physical process. But mathematically, you do not need to build anything, it reduces to a mathematical problem: give a space, a metric, some second order equations, and the problem should be either well defined or not. Apparently Newton's law does not define a well posed mathematical problem for the case of homogeneous density and infinite space.
Apr
17
comment Is Newtonian gravity consistent with an infinite universe?
@Chris thanks for the attempt, I'll answer my doubts below your answer.
Apr
15
comment What happens at the interface between two universes with opposite thermodynamic arrows of time?
assume the two universes are disconnected for most of their history, and become connected at some point in the middle for a finite amount of time (trough a wormhole?). It doesn't matter if you name it a single universe or two, what matters is that the thermodynamic arrow of time is in the opposite direction between them, at least when they are not connected
Apr
14
comment What happens at the interface between two universes with opposite thermodynamic arrows of time?
Thanks! I'll read it!
Apr
13
comment Is Newtonian gravity consistent with an infinite universe?
The best I could bet from the redirected question is this quote: "However, the mass can't be negative and the energy density is positive. This would force a violation of the translational symmetry in a uniform Newtonian Universe". It still doesn't give a satisfactory answer. For instance: how is that symmetry broken if we assume that there is no noise nor small density fluctuations in the system? How can you choose then the absolute "origin" that will break the symmetry? Still doesn't make sense to me.
Apr
11
comment Is Newtonian gravity consistent with an infinite universe?
Thanks, I'll try to find that, in the meantime is there any reference that you can give me? I would be very happy to accept your answer if that seems to be the mistake in my argument!
Apr
11
comment Is Newtonian gravity consistent with an infinite universe?
@Ben, I already mentioned homogeneity (I know the system is unstable). What I am not sure to understand and you could have a good point is that sums are not associative (and why are they not? I am not sure to understand that). But I am not sure on what part you apply that argument.