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Showing content with the highest reputation on 02/15/24 in all areas

  1. If you want to make arguments to support these assertions you are welcome, but stating them doesn't make them true. In my experience pretty much only staunch doubt, deny, delay opponents of addressing global warming seem chronically unable to update what they are sure they know about climate science or climate policy or options for doing something, like renewable energy. Around 3/4 of all new electricity generation being added around the world is now solar and wind, on their merits, as commercial decisions - not out of deep commitment to zero emissions (although the possibility of emissions accountability emerging in the future does figure into investment decisions) but because of this - .
    3 points
  2. Be nice! It's still a heavenly body...
    2 points
  3. The protons are already fused, at least for an instant or so. I have a question for you, if 2 protons fuse together what is the resulting product? That's true, but it has nothing to do with what we are discussing in this thread as far as I can see.
    1 point
  4. There is no distinction between push and pull; both are forces. However there are many forces, and F=ma is a generalized force equation expressing what happens to a test mass, m, when a force is applied to it. It is also known as Newton's second law. The other equation F=GMm/r2 is a specific kind of 'force', that expresses what happens to a test mass, m, when exposed to the gravity of another body of mass M. This is also known as Newtonian Gravity, and the model is accurate in most situations, although in some situations involving hi energy/lo separation Gravity is better described by a geometrical space-time ( which is not a force ) model, GR . The two equations can only be set to equal when dealing with the gravitational force of mass M, on test mass m. And in such a case ( as Swansont showed ) we notice that the mass m cancels from both sides. This means the acceleration induced by a body of mass M is independent of the test mass, m. IOW, all test masses, no matter what their m is, accelerate/fall at the same rate when exposed to the same Gravitational Force of object M. In the case of M being the mass of the Earth, we realize that climbing to the top of the leaning Tower of Pisa to drop a bowling ball and a golf ball, and timing their time to fall, is not necessary. They both fall at 9.8 m/s/s. ( disregarding air resistance, of course )
    1 point
  5. Those were words by Kepler. It's Latin for 'wherever there is matter, there is geometry'. It goes to prove that the idea that geometry held the key to understanding physics has been around for a long time. The factoring out of one of the masses from the equation of motion (or the fact that you could talk about gravitation without without one of the masses not really being there, and the other being replaced by energy, as Genady suggested) is a subtle clue that geometry is at the core of gravity. As to push or pull, I think you mean something about attractive vs repulsive forces perhaps? But then it's not about F=ma vs F=GmM/r². F=ma is the definition of force. It's a definition, rather than an equation really. F=GmM/r² is a law of force, and it has a very different content. It's when we equate both, as @Janus illustrated, ma=GmM/r² that we do have an equation, ie, an equality to be solved. The mere F=ma cannot be solved. Definitions cannot be 'solved'. Not all equalities are equations. This is a common misconception. There are definitions, identities, formulas and equations. Definition: velocity=space/time Identity: x²-y²=(x+y)(x-y) Equation: x²-2x+1=0 Formula: (c1)²+(c2)²=h², where c1 and c2 are the catheti of a right rectangle and h is the hypotenuse of the same triangle A definition is just a labeling, an identity is an algebraic equivalence that's always true, an equation is the expression of a hypothesis to be solved from its statement in the algebraic language, and a formula is an algebraic statement involving ideas that can be abstract, geometrical, etc. There is a long tradition of calling physical laws, definitions (and perhaps formulas) all 'equations', which might be at the root of your confusion.
    1 point
  6. Evidently, "Details matter" in the other thread... Let's fix it:
    1 point
  7. A lot of importance is given to Faraday's new electromotive motor and there is considerable hype that it might be amenable to practical applications where Mr Watt's engine proves cumbersome. However it's hard to see this ever going beyond a few niche markets, given the considerable expense and labor involved in the fabrication, not to mention the problems of creating a wide availability of electrical generation and transmission. Mr Faraday's device appears to be more a toy than a real solution in providing mechanical power in quotidian uses.
    1 point
  8. [math]1 + \alpha = \dfrac{(4 - \phi^2) - \sqrt{12 \phi^2 - 3 \phi^4}}{2 (1 - \phi^2)}[/math] From here, I took a shortcut and simply ignored the two [math]\phi^2[/math] outside the square root and the [math]3 \phi^4[/math] under the square root because I could see that these are not going to be a part of the final result. Thus: [math]1 + \alpha = \dfrac{4 - \sqrt{12 \phi^2}}{2}[/math] for [math]x \to 0[/math] (ignoring higher-order terms) [math]1 + \alpha = 2 - \sqrt{3} \phi[/math] However, one can verify that the shortcut leads to the same result as follows: [math]1 + \alpha = \dfrac{(4 - \phi^2) - \sqrt{12 \phi^2 - 3 \phi^4}}{2 (1 - \phi^2)}[/math] [math]1 + \alpha = \dfrac{(4 - \phi^2) - \sqrt{12} \phi \sqrt{1 - \dfrac{1}{4} \phi^2}}{2 (1 - \phi^2)}[/math] The series expansion of [math]\dfrac{1}{1 + x}[/math] and [math]\sqrt{1 + x}[/math]: [math]\dfrac{1}{1 + x} = 1 - x + x^2 - x^3 + \cdots = 1 - x[/math] for [math]x \to 0[/math] (ignoring higher-order terms) [math]\sqrt{1 + x} = 1 + \dfrac{1}{2} x - \dfrac{1}{8} x^2 + \dfrac{1}{16} x^3 - \dfrac{5}{128} x^4 + \cdots = 1 + \dfrac{1}{2} x[/math] for [math]x \to 0[/math] (ignoring higher-order terms) Thus: [math]\dfrac{1}{1 - \phi^2} = 1 + \phi^2[/math] for [math]x \to 0[/math] (ignoring higher-order terms) [math]\sqrt{1 - \dfrac{1}{4} \phi^2} = 1 - \dfrac{1}{8} \phi^2[/math] for [math]x \to 0[/math] (ignoring higher-order terms) [math]1 + \alpha = \dfrac{1}{2} (4 - \phi^2) (1 + \phi^2) - \sqrt{3} \phi (1 - \dfrac{1}{8} \phi^2) (1 + \phi^2)[/math] [math]1 + \alpha = \dfrac{1}{2} (4 + 3 \phi^2 - \phi^4) - \sqrt{3} \phi (1 + \dfrac{7}{8} \phi^2 - \dfrac{1}{8} \phi^4)[/math] [math]1 + \alpha = 2 - \sqrt{3} \phi + \dfrac{3}{2} \phi^2 - \dfrac{7 \sqrt{3}}{8} \phi^3 - \dfrac{1}{2} \phi^4 + \dfrac{\sqrt{3}}{8} \phi^5[/math] [math]1 + \alpha = 2 - \sqrt{3} \phi[/math] for [math]x \to 0[/math] (ignoring higher-order terms)
    1 point
  9. No, I am turning alpha particles into a proton pair and then waiting for them to fuse by applying energy. If you have a naturally decaying radioactive source such as C-60 which emits gamma radiation then you would not need to worry about input energy. Its just naturally supplied.
    -1 points
  10. I will not fall for your insulting provocation. This is for children and frustrated people. Rubbish is your unfounded protest. Why can’t we assume the universe as the reference frame? NASA uses the UNIVERSAL CMB RADIATION as reference frame in its space ship, to determine its REAL speed. You are attached to outdated concepts. See: https://einstein.stanford.edu/content/relativity/a10854.html I agree!!! You contradicted your own previous statement. You cannot use wrong premises of the old outdated BBT to confront the theory opposite to it. At what distance is gravity trivial? Give me a number in Gly or mpc. If you give that number, (which I doubt you do), we could say that a body at half that distance would would still be gravitationally counted, both by us and for a body at that supposed distance of gravitational triviality. That is why there is not such distance, the universe is fully connected. BBT is a dogma. No, the increment in the mass energy of the atom due its shrinkage is neglected when compared with the total energy of atoms. Nice but failed attempt to bring the subject of gravity into this thread. Gravity is a controversial topic that should be, (and already is), addressed in a specific thread. For now, I can say that gravity is the property of energy to concentrate.
    -2 points
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