MigL

The energy of empty space is actually very small; there just happens to be a HUGE amount of empty space. Unfortunately, that energy is unavailable, either for use, or in calculations ( 120 orders of magnitude discrepancy ). The 'empty' space of a Black Hole, however, is not the same 'empty' space. That space is defined by its Schwarzschild radius, and the resultant Event Horizon. Classically, the Event horizon conserves mass/energy, charge and angular momentum; there are various ways to extract energy from a massive, charged, spinning system. Semi-classically ( with some Thermodynamics and QM ) that space has a temperature, and depending on size, can radiate considerable amounts of radiative energy ( Romulan ships in the Star Trek universe employ a miniature BH as a power source as opposed to the matter/anti-matter process used by the Federation )

I don't see how we 'shape' our part of the universe, or 'create' the future. We interact with the only part of the universe that the speed of light/information allows us to. If that is what you are saying, then ... yeah; but it's no big revelation, it is a fundamental principle.

I am arguing that the levelling and unification of interactions make it unlikely that an electron can be modelled as a BH. Not that it makes it possible. Which is still a classical solution. You are the one who brought up the observation that the classical picture is insufficient, and Quantum gravity may modify the situation. Why can't I do the same ?

Exactly ... Quantum Gravity. The exact same new Physics KJW proposes that might allow for electrons to be quantum ( not classical ) Black Holes. It's expected ) though not certain ) that as Planck scale is approached, gravity becomes comparable in strength to the other forces and can no longer be ignored. There is a further expectation that all the fundamental forces are unified at that scale. Most theories, including Sting Theory and LQG, favor the unification of all fundamental interactions.

I have used the two-part lids. They usually come with Mason jars, used for 'canning' home-made preserves such as jams, peach slices in syrup, cherries in alcohol, even pickeled vegetables or tomato/pasta sauce ( I used to help my mom when I was young ). They are similar in operation to the other 'tabbed' lids, and both have a rubber friction ring where the lid contacts the glass. The usual procedure is to fill with hot preserves and cap tightly with the threaded ring, on the now soft rubber sealing surface of the lid. As the contents ( and the rubber seal ) cool, the head space will now be at a lower pressure than atmospheric and the seal will re-harden to provide a not-easily slipping seal. The seal is almost always good enough that the threaded ring part of the two-part lid can be removed without loss of seal for years, and the ring re-used for next year's canning ( for the frugal among us ); however the lid part cannot be re-used, but they are available separately without the threaded ring. I keep my jam/marmalade in the refrigerator once opened, and putting them back in the fridge to cool again after use, makes them very hard to open the next time. A little bit of differential pressure makes for a good seal. FYI Airplane doors are not 'locked'; it is their design ( 'plug' ), and a couple of pounds of DP, that keeps them from opening, although there have been one or two occasions where a 'crazed' passenger has managed to open a door and depressurize the plane ( probably at lower altitudes ).

I don't believe in singularities; much, much less so the idea of naked singularities. Are you sure ? The Coulomb interaction would provide a large potential barrier, but at high enough energies/small separations gravitational potential would be strong enough to mitigate, or possibly cancel, the Coulomb interaction. But we seem to be in the area of opinions, not verifiable facts. The only description we have of Black Holes is classical; even Hawking's ( and Bekenstein ) radiating model only incorporates a few aspects of a quantum model, so when you say "not a classical Black Hole' how are we to interpret that ? I agree, maybe Quantum Gravity may eventually provide answers/clarifications, but all we have now are currently accepted models, and they seem clear ( to me 😀 ) that elementary particles cannot be modelled by our current understanding of Black Holes

Come on ! We are on the second page of discussion on opening jars ? Some of the members here can probably calculate the trajectory for a moon landing. I didn't think jar lids would be such a problem; most housewives can manage 😄 . ( I can imagine the problems you guys have doing laundry )

At this scale I tend to trust Quantum Mechanics and Thermodynamics more than I'd trust GR. A Black Hole is a perfect black body, and must have a characteristic temperature. In your analogy, the problem is not that an electron cannot orbit the nucleus ( it certainly may ); the problem is that it cannot be a classical particle. Similarly in the problem being discussed, it is not that Black Holes do not have a temperature ( and may radiate depending on that temperature ), but rather that they cannot be Black Holes. ( what would you get when you scatter a BH electron off another ?? )

Due to the finite speed of light/information, and the universe's finite age, our specific Cosmological Horizon limits what can affect us and what we can observe from the center of our horizon. It is currently defined by a radius of about 46 Billion Light Years, but it grows with time. There are also horizons in time. The past one being defined by the CMB, or surface of last scattering, beyond which light can't observed ( butneutrino and even gravitational waves may eventually provide previous horizons ). And the future one defined by the Event Horizon, which events will never be able to affect us, even in the future.

As Markus has pointed out, a Black Hole's temperature is inversely proportional to its size. A small sized Black Hole the size ( mass ) of the Earth would have a temperature of 0.02 degrees K. An extremely tiny BH with the mass of a person would have a temperature of 1021 degrees K. The upper bound for the size of an electron is 10-18 m so its temperature, if it was a BH, would be in the order of 1030 degrees K. And the relationship for luminosity due to emitted radiation is given by L = AoT4 Where A=4*Pi*r2 and o is the Stefan-Boltzmann constant. I'm sure we would have noticed such extreme effects by now ....

This is not Philosophical. It is the very idea that allows us to do science, and it is called the Cosmological Principle. "The cosmological principle is usually stated formally as 'Viewed on a sufficiently large scale, the properties of the universe are the same for all observers.' This amounts to the strongly philosophical statement that the part of the universe which we can see is a fair sample, and that the same physical laws apply throughout. In essence, this in a sense says that the universe is knowable and is playing fair with scientists." Astronomer William Keel from https://en.wikipedia.org/wiki/Cosmological_principle IOW, this means that the universe looks the same from everyone's perspective, has no special center or edge, and that the laws of physics are the same everywhere and at all times.

Those always go missing just when you need them. When you don't need them, you're tripping over the three extra sets you bought because the originals were missing when you needed them. Or, maybe you guys are feeble, and I'm forgetful of where I put things.

All you feeble old men should head down to a nearby dollar store. They sell a V-shaped contraption that screws onto the bottom of your kitchen cabinets ( out of sight ), and when you need to open a jar lid, you push the jar lid into the V, which has a friction surface, and turn the jar. Easy-peasy. Incidentally ... your fingers are weaker than your thumb, so always turn in a direction that tends to 'tighten' your fingers. ( think of a pipe wrench )

Moon landing deniers, and all other conspiracy theorists, can come up with so many ( un )plausible explanations while there is only one truth that uninformed people are unlikely to receive on their social media feeds.

My 1st year Uni, in '77, when you had to go physically sign up for courses, I saw the team slogan and signed up for rugby. The slogan was "you gotta have leather balls to play Rugby". Yes, it was fun while it lasted; then it turned to a broken collar bone.

I would think 'hygiene' might be better termed exposure. Exposure to biological pollutants during the crucial formative period of a child's auto-immune system might reduce the allergic response later in life. There is, after all, a condition called Pica, which affects expectant mothers as a craving to eat dirt. It is attributed to iron deficiency, but it may be partially attributed to instinctive behavior as a way for the mother to 'expose' the fetus to biological pollutants. I myself, am allergic to ragweed/goldenrod, having lived almost my first decade in Italy, where these weeds are not common. The allergy came on suddenly in my late twenties ( thought I had a cold for the months of September and October ), but gradually went away by my 50s; so there is hope String Junky. I am also allergic to Alpha blockers ( eye drops ) which manifests as red bumpy irritation under my eye-lids and blurry ( more so than usual ) vision. No other allergies.

It is not so much 'things coming our way', rather the fact that our solar system is travelling around the galaxy. "The Sun moves in a roughly circular path around the center of the Milky Way galaxy, a journey that takes about 225 million years. This primary orbital motion is accompanied by a perpendicular "bobbing" motion as the Solar System oscillates up and down through the galactic plane, with a period of approximately 63 million years. The speed of this motion is roughly 230 kilometers per second (about 828,000 km/hr.)" So it is entirely possible that we are overtaking interstellar objects moving slower than we are, being overtaken by faster moving objects, and intercepting objects as we weave 'up and down' the galactic plane. Relativity makes it appear we are being 'visited', where we may, in fact, be doing the 'visiting'.

And when California decides to have a referendum on re-drawing their electoral maps, to mitigate the effects of the Trump backed re-drawing in Texas, California gets slapped with a lawsuit by the personal lawyer hacks he has appointed to lead the Justice Department. You can't even make up this level of hypocrisy.

Let it go @studiot . After all, even D Trump says that no one knows what magnets are ... Trump, 79, Claims Nobody Knows What a Magnet Is surely you don't doubt anything D Trump says !

The Democrats approved it. It is not a vote for the general public. We had a 'polarized' freedom with both sides represented. Now we have FOX and right wing media, while every one else is afraid to get sued. Sure. Everyone was free to study and say as they wished. Now, if you don't agree with D Trump's views you get your funding cut. Never very easy because of Republican shenanigans. Has gotten seriously corrupted wit D Trum's efforts to rig the midterms by re-drawing electoral maps. Democracy isn't perfect, but it was immensly better before D Trump got involved. Yes, this is a science forum, and all of us can tell that it isn't getting any better, as you seem to believe.

That's right. On this site we like to comply with requests.

It's a 10 l reservoir 😃 ! But yes, I see what you mean.

Ignoring D Trump for now ... What V Putin wants is to save face and retain power. He knows he has lost this war, but cannot quit as he will be humiliated, lose all credibility as a 'strongman', and 'replaced'. He is constrained to keep going, no matter how much he ruins the country, or the attrition of equipment and personnel. As for China and Taiwan. Although D Trump, and Republicans, are driving the US towards isolationism, China knows that any attack on Taiwan will bring some response from the US due to dependence on electronic fabrication. Since they don't know the scale of the American response, their only hope for success is eliminating the American threat in the area. That means pre-emptive strikes on American assets on Japanese and Philippine air bases which have little, if any, hardened aircraft shelters, and bring Japan, US, and the Philippines into the war. To cover the landing invasion, China will need to blanket Taiwan with missile attacks thereby destroying Taiwan's semiconductor manufacturing capabilities. TSMC is not a world leader in semiconductor design, but can produce them at design scales surpassing any other manufacturer in the world. It will eventually bog down to a logistical nightmare, even if China manages to establish a beach head on Taiwan, as they will not be able to re-supply them. So they will either bog down into a war of attrition, continue with the missile barrage rendering Taiwan useless to them, or evolve to a nuclear exchange. I don't think China welcomes any of those possibilities, but they are very good at playing the long game, and will simply wait until D Trump and Republicans finish destroying America, as they are their main opposition.

Well, ... yes. Feedback is self correcting, and require only some limited knowledge of how the system will evolve. Feedforward only works if you have considerable 'a priori' knowledge of how the system will evolve, so corrections can automatically be made as needed throughout its evolution. And this method seems kind of useless to me. If you know enough about the system to predict the corrections that will need to be made so as to restrict deviations and divergences while the system evolves, could you not build the 'corrections' into the initial conditions and eliminate the need for feedforward controls ? For example ... Say I'm filling a 10 l reservoir with an inlet flow of 2 l/min and an outlet flow of 1 l/min. and want to prevent overflowing. After a period of time, the reservoir will be close to overflowing, so a 'feedforward' control will open the outlet to 3 l/min to bring the reservoir down to an acceptable level before resuming the original rate. This assumes I can calculate when the feedforward controls need to be active to prevent overfilling ( easy calculation ). But knowing all this, could I just as easily set the initial conditions such that the inlet and outlet flows are equal to prevent overflowing ?

Some of the previous discussion concerns the unalterability of some fundamental constants It is interesting to note that the one-way speed of light has never been measured, as a matter of fact, it cannot be measured due to causality considerations. We can only ever measure the round-trip speed of light from a reflection. And although we have many other ways to conclude the value of c is fixed ( the original being J C Maxwell ), we have no empirical evidence that reflected light behaves the same as incident light. ( only principles such as Cosmological, Equivalence, Invariance of Relativity, etc. ) P.S. This arises from my interest in causality as of late.