Recent content by Alfredo Tifi

Thank you all for your thoughtful rebuttals, which eventually convicted me of the non-contradictory nature of a small velocity for the tiniest body or even at rest (zero velocity) unless the body is not completely converted and disappears, together with the hypothetical contradiction. I have...

Replying to Ibix and Dale. You should consider this as a "gedankenexperiment", as was the one of Einstein. Then, what is strange, or paradoxical, is what concerns the remaining energy-mass, which is "slow". Let's take another, simpler, case. The body has a dynamite charge which explodes sending...

After emitting two photons (or any other kind of energy) in the direction of motion and in the opposite direction, the velocity of the body (a big charged and unstable particle) remains unchanged, while the kinetic energy decreases. This entails a decrement of the rest mass, or of the inertia of...

I didn't consider the perspective of starting with a cloud of static particles. This is interesting and better because rotation will ensue from a static random configuration. But it is evident that orbital plus spin angular momenta would give a zero sum. In our Solar System everything is...

The probability of nonzero AM should be much less as much bigger was the Angular Momentum. That is we should have a zero-peaked distribution of probability if we could prepare a "canonical ensemble" of equally randomly prepared clouds. But, I don't think we can talk of probability if momentum...

A possibility is that, together with many other articles that have been translated from English in that magazine issues, also Liuzzo's one was originally in English and, as often occurs, badly translated (without her checking!) I want to try to ask to the redaction, on the behalf of the...

Thank you anurlunda; I enjoyed the "potatoids" and the protoplasm formation. I'm very happy to learn so many forms of dissipative mechanisms in the dense protoplanetary disk and angular moment transferring. All the article confirm that the total angular moment is exactly conserved, even though...

I suppose that the principle of conservation of angular momentum holds also for a cloud of particles weekly interacting at low pressure, density and temperature. And it should be still applicable when the particles or the atoms would start condensing and forming fusion products or simply solid...

This is an extract from Liuzzo’s article “L’ombra del buco nero e la foto del secolo”, published on Magazine Micromega, 4/2019. I copied it from the ebook I’ve bought today. It is not available online. She is speaking about the famous photo... “L’immagine ci dà inoltre un’altra informazione...

Problem Statement: It is possible to describe synchrotron radiation as caused by a loss of electrical charge of relativistic particles that are moving in a magnetic field? Relevant Equations: E = mc2 An Italian expert of black hole M87 (Elisabetta Liuzzo) explains that the expected axial...

Thank you Ibix and Dale. Absolute circularly accelerated motion here is specular to relative uniform motion (in a qualitative Galileian sense of having or not having a velocity, that is just a matter of reference systems, not of invariance). If the reference system O' associated with the probe...

I refer to the second paragraph of 1916's book, "Die Grundlage der allgemeinen Relativitätstheorie", translated here. First issue There are two distant stellar bodies, with unchanging shapes: S₁ (spherical) and S₂ (ellipsoidal), made of the same amount and kind of matter. Their centres of mass...

No. From the answers, I gather the convincement that what happens in the apparatus only depends on how the apparatus has been prepared and what is running in. It is not influenced by human knowledge. And this is pretty fine because it confirms a realism principle about Nature. Knowledge is...

Thank you Janus. I really appreciated your perfectly convincing arguments. So now two options only remain open: a) dark matter exists; b) relationship between mass and gravitational field has to be corrected (Scientific American article "Is Dark Matter Real?", by Sabine Hossenfelder and Stacy S...

The reading is from Scientific American article "Is Dark Matter Real?", by Sabine Hossenfelder and Stacy S. McGaugh, August 2018 (published in December in the Italian version).