MigL

You uys seem to be talking past each other. A geometric field theory of gravity does not require a mediator particle, as Mordred states; it is 'sufficient' on its own. Yet we know that it isn't exactly 'sufficient' at small separations/hi energies, and a quantum field theory of gravity is required to cover those areas of applicability. We also know that a quantum field theory of gravity does require a spin2, massless mediator particle which we have termed the graviton, as MisterMack states. It could be quite a while before quantum gravitytheory and gravitons are an established fact, though.

Didn't notice this when you first posted a couple of years back, but that 1038 times is actually 1038, or 38 orders of magnitude weaker. Same goes for the other numbers posted. Keep in mind that this is at atomic particle scale; if you compare at scales approximately 10 times the mass of our sun, you will find that gravity is the strongest and no other interactions can resist gravitational collapse to a Black Hole As Studiot mentions in the first answer, scale matters. A lot of the differences between Newtonian gravity and GR are due to temporal curvature. The anomalous orbit of Mercury, in the strong gravity field of the Sun, is mostly due to temporal curvature..

It is very difficult to think of an analogy for negative gravitational pressure. Think of it as a coiled spring. Gravity, in GR, acts on all forms of energy, and if gravity were to compress this spring slightly, its gravity would further increase because of the added energy of compression. This would be an example of positive gravitational pressure, and gravity acts like we expect it to. Now, for the negative pressure example, the best I can come up with is a stretched spring, under tension, but it's not gravity that's pulling it apart ( no such thing as repulsive gravity ) rather, it is the universe itself through the gravity field, or Cosmological Constant, aka Dark Energy, that is doing the stretching. This CC or Dark Energy is a scalar term that does not vary with distance, whereas the rest of the gravitational terms do, and so we have gravity dominating at close distances. But when gravity decreases with the square of the distance, it is a given that at a certain distance the gravitational terms will be less than the CC or Dark Energy term, resulting in expansion. Sorry if I could not be clearer.

Interesting read, Mordred. I especially enjoyed the speculative sections near the end.

I'm very particular about social contact also. I would prefer if fat smelly old men kept their distance. However, Covid or not, good looking women can hug me whenever they want ...

On the other hand, my front wheel bearing is getting noisy. Any 'theories' on the easiest way to knock out the bearing ? But seriously, the only part of your post I'll agree with is that 'prior to the Big Bang and inflation,the universe may have existed in a razor's edge equilibrium for a very long time, depending, of course, on how one measures time in a universe where there is no time yet. The Big Bang was the disruption of that equilibrium.

If I may ... It makes no sense to talk about energies needed to create a universe at the beginning of time. Noether's theorem states that 'every differentiable symmetry of the action of a physical system with conservative forces has a corresponding conservation law'. If a process exhibits the same outcomes regardless of time. then its Lagrangian is symmetric under continuous translations in time, and as per Noether's theorem, this symmetry accounts for thelaw of energy conservation of this system. ( paraphrased from Wiki ) As the beginning of time is decidedly non-symmetric, the energy conservation law is not constrained to hold, and the quantum fluctuation would not be constrained in the amount of energy it could introduce to the system. Maybe enough to create a universe.

Notice that I did not call you any of those; what I said was 'hare-brained ideas' . IOW, a criticism of your idea, not you personally. Judging by your answer, however, one could be led to believe that you may have been accused of those qualities previously.

That's gotta be a lifetime's worth of nail clippings. Some people collect the most odd things. And I do use a SS stovetop espresso maker , but I have a few small 1-2 cup traditional aluminum ones. Those are the ones I remember from my youth in the 60s and 70s, Eise; like the Motta model in your photo. The link between Alzheimer's and Aluminum has never been factually estabilished, and while the prevalence of Aluminum cooking utensils has decreased dramatically over the last 40 years, the incidence of Alzheimer's has increased considerably during that time ( expected to almost double in 20 years ).

Yeah ... Right. ( why do all these hare-brained ides involve pyramids and vortices ? )

100 espresso pods at CostCo for Can$ 30, comes to 30 cents per espresso. ( as compared to Can$ 2.50 at the coffee shop down the street, never mind Starbucks ) But it's more about time and effort saving. Isn't that what money is for ? Personally I prefer the stove-top percolating aluminum espresso makers. When I was younger my dad would make espresso on Saturday mornings because he didn't have to work. The aroma would spread through the house and wake me when it started percolating. Every once in a while, when tme allows, I'll make it that way, just to re-live those memories.

You just kicked the can down the road. What is 'fair', to whom, and who gets to decide ?

Nespresso. Drop in a pod. Push the button. Enjoy your espresso.

People keep kicking them. They handle one more than the other. Looks like you had a vasectomy; one still has visible stitches ...

Not without defining 'moral' first. ( do you consider 'moral' an axiom, or self apparent truth ? ) We should all be talking about the same thing, should we not ?

If you're going to 'make fun' of anybody's appearance, at least have the balls to post your own photo ( not Brad Pitt or Leo DeCaprio either ) so we can compare ... Or maybe post in the Political Humor forum.

Is it morally acceptable to want the best for your kids? Of course it is. But we know it is wrong to pay to get them accepted into a prestigious school; and people have gone to jail for that. Or is it? Many people get away with it by making 'donations'. Who draws the line ? Is it morally acceptable to steal from a crook? Most people would be confortable with that. How about when that robbery gets the crook killed by his mob boss? I could give many such examples of ambiguous 'morals' and 'ethics'. People usually subjectively justify what is good for themselves; there is no absolute morality.

who's ethics and who's morals are you considering here, Dim ? And why do they supersede other's ethics and morals ? You do realize that they are subjective concepts and differ for different people, don't you ?

The principles that must be respected by GDPR, in the EU, are fair and lawful processing; purpose limitation; data minimisation and data retention. How is Science Forums violating these principles ?

In Star Trek OS, A Taste Of Armageddon ( S01E23 ), the Enterprise is accidentally caught in a simulated attack between two worlds that have been at war for 800 years. They have 'sanitized' war, with simulations and disintegration chambers for those targetted, so much that there is no reason to end wars or avoid them in the first place. Kirk decides to destroy the targetting computers, give them back the horrors of real war, and tells them to start negotiating a peace if they want to avoid those horrors. Drone strikes, proxy wars, and other means of sanitizing war are counter-productive. It is the horror of millions of people losing their lives that helps prevent it from happening. ( yes, I've learned many life lessons from Star Trek )

Exactly. The inherent infinities cannot be 'renormalized' away, and make the theory unworkable and incapable of making any valid predictions. Hope your time away from the forum wasn't all work ...

All computers, no matter the technology used, have a common property Garbage in ... garbage out. IOW, if you don't know how to solve the problem, you cannot program a computer to do it.

In any quantity of water there are a number of molecules which dissociate and re-associate H2O <> H+ + OH- The potential Hydrogen is an inverse logarithmic measure of the number of H+ ions in solution and their reactive potential; and the reason water has a 'neutral' pH of 7. I'm sure Wikipedia has an entry for pH.

I have mentioned this many times in the past; frames of reference are very important in relativity. Considering an event from the wrong frame usually yields nonsense, and has led to much confusion in past threads. Leaving aside the fact that a FtL ship is already capable of violating causality, it may, in fact, be possible for a FtL ship to send a FtL message without violating causality, but only in the frame of that FtL ship. That doesn't change the fact that it will violate causality for every other timelike observer who is not in that particular frame. That is also what a space-time diagram does, Moon. It separates the timelike ( where events are separated by an interval which allows for causal connection) from the spacelike ( FtL domain where events cannot affect other events ) by the lightlike line ( the SoL ). A 3dimensional representation would be a light cone.

Are we watchig the same video Moon ? At 17 min he says 'the problem of causality violation is not with relativity but with FtL itself". Your misunderstanding may stem from the fact that you are missing an important bit of information which he last explains at 14 min. He says that the "world line defines the time axis as perceived by those following it", further he states "the time axis for the crew of that FtL ship actually lives along that timeline". The rest of the universe does not. So while an FtL transmission from an FtL moving ship may not violate causality to those aboard that ship only, the fact remains that they are already violating causality by moving FtL. I suggest you re-watch without your 'wishful thinking' glasses on.