# Search results

1. ### I What if a body loses 86,6% of its mass as couples of gamma photons?

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...
2. ### I What if a body loses 86,6% of its mass as couples of gamma photons?

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...
3. ### I What if a body loses 86,6% of its mass as couples of gamma photons?

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...
4. ### I Why do nebulas, stars and other objects such as galaxies and black holes develop a rotation?

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...
5. ### I Why do nebulas, stars and other objects such as galaxies and black holes develop a rotation?

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...
6. ### Relativistic particles losing their charge in a magnetic field?

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 wanna try to ask to the redaction, on the behalf of the Principle...
7. ### I Why do nebulas, stars and other objects such as galaxies and black holes develop a rotation?

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...
8. ### I Why do nebulas, stars and other objects such as galaxies and black holes develop a rotation?

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...
9. ### Relativistic particles losing their charge in a magnetic field?

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...
10. ### Relativistic particles losing their charge in a magnetic field?

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...
11. ### B Is rotatory motion absolute?

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...
12. ### B Is rotatory motion absolute?

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...
13. ### I Would this experiment disprove that consciousness causes collapse?

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...
14. ### B Dark matter is "normal" matter in black holes?

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...
15. ### B Dark matter is "normal" matter in black holes?

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).
16. ### B Dark matter is "normal" matter in black holes?

Do we know the "tiny" ratio of black hole mass to total mass in the milky galaxy? How do we measure the mass of other galaxies' black holes?
17. ### B Dark matter is "normal" matter in black holes?

I read that 1. dark matter has to be concentrated in galaxies; 2. McGaugh & Co discovered a precise relationship between visible-ordinary matter and the calculated sum of ordinary + dark matter from thorough observation of actual acceleration of more than 150 galaxies. 3. First experiments to...
18. ### I Why did Einstein considered it “evident”?

This is true, of course, because further reflections would convict us that mass and internal energy should be invariant (substantially the same invariant). The reader of Einstein's paper only understands what he wrote: that the observer in motion calculates a decrease in kinetic energy not due...
19. ### I Why did Einstein considered it “evident”?

Thank you very much Fresh_42 for your in-depth exam. Along with this translation, we could reason that Einstein's calculation would hold for any kind of transition from any kind of emitted energy (included thermal) even though it is not eventually converted in radiant energy. So, E = mc² is...
20. ### I Why did Einstein considered it “evident”?

Thank you. I did correct the mistake and re-phrase some parts hoping it is clearer now.
21. ### I Why did Einstein considered it “evident”?

At the end of the (fourth), 1905’s E=mc² paper Einstein claimed: “The fact that the energy withdrawn from the body becomes energy of radiation evidently makes no difference”. This sounds odd to me, given that the change L(γ-1) in kinetic energy resulted from calculating radiation energy. Light...
22. ### B Do photons experience time?

The reference system of the “fast” object Measures a velocity c respect to the photon. It’s time is relented only if watched by another reference system, but it’s own time “proper time” is unchanged and its “perceptions” are unchanged. Given that a photon don’t have a reference system, we can’t...
23. ### B A new paradox? I can’t fix it anyway!

Thank you Dale and Orodruin. I see now there is no paradox given that a single photon can’t undergo pair production. The paradox would have been of events (pair production) occurring for an observer but not for another one with only a slow motion. I was aware that energy of photons depend from...
24. ### B A new paradox? I can’t fix it anyway!

A monochromatic gamma light source S emits photons with spherical symmetry. These photons have a little less energy than necessary to permit formation of particle - antiparticle couples (electron-positron couple) or “EPCs”. An inertial observer O moves towards S with a small fraction of light...
25. ### I Wheeler's delayed choice doesn't change the past

"Obviously, deductions or interpretations would be more mingled with the theory on the bench than it occurred [in] the past." I missed [in] before "the past". But I see it is not enough to make sense of this thought of mine. I'll try to express it better. First, usual theories address what is...
26. ### I Wheeler's delayed choice doesn't change the past

I like your wise reply and opinion about Copenhagen break up between micro/macro realities. That means that either the theory is incomplete or classic reality is an illusion of the macroscopic world. I know speculation is not liked in this forum, but it is evident that the classic idea of...
27. ### I Wheeler's delayed choice doesn't change the past

Maybe this kind of "pruning" coincides with Hawking top-down approach, and both remember to me something similar to an "Anthropic Principle". I want to quote Hawking's argument about his application of Feynman sum to the entire universe, two chapters later (pages 135, 136, 140). «If the origin...
28. ### I Why isn't the Roemer type experiment a one way measure of c?

I don't understand what actually this sentence implies: 1. anisotropic respect to the Jupiter--> Earth and Earth --> Jupiter directions? This is totally arbitrary to me given that absolute space doesn't exist. Any anisotropy could be used to establish preferential landmarks or directions. 2...
29. ### I Why isn't the Roemer type experiment a one way measure of c?

I can't read the tons of posts and replies about one-way light speed in this forum. I was criticised once for sustaining light speed should be equal in both outward and return trips and Einstein's method of syncing clocks as the only reasonable one. Then I studied some scientific articles gently...
30. ### I Wheeler's delayed choice doesn't change the past

Maybe Mlodinow wrote that. Here is the book, check pages 82-83 https://goo.gl/images/Z6N9gr.