Strange

If you have a cloud of gas or dust and let it expand, it will spread uniformly (each atom or particle will move away from every other). This will lead to a larger, less dense cloud. But it won't have a void in the middle.

This is actually one of the big unanswered questions. The current best hypothesis is that the universe achieved equilibrium when it was very small and then rapidly expanded (inflation).

The universe has always been (roughly uniformly) full of matter/energy. This means that the early universe was very hot and dense. As the universe expanded it cooled and got less dense.

Special relativity says that two things cannot move relative to one another faster than the speed of light. This only applies locally in the absence of gravity and curved spacetime. General relativity is the basis of the big bang model; that the universe is expanding. This is expansion is a scaling effect, so distances get multiplied by some factor in every unit of time. For example, consider a number of galaxies separated by the same distance (far enough apart that the expansion of space is significant and the same between all of them). At time 0, they are 1 unit apart: A.B.C.D.E.F After some time they are 2 units apart: A..B..C..D..E..F After the same time again, they are 3 units apart: A...B...C...D...E...F And so on: A....B....C....D....E....F Now, if we look at the distance between B and C, for example, it increases by 1 at every time step. But the distance between B and D increases by 2 at every step. So the distance between B and D is increasing twice as fast as the distance between B and C; i.e. the speed of separation is twice as great. Choose any pairs of galaxies and you will see that apparent the speed of separation is proportional to the distance between them. Take two objects far enough apart and the speed of separation will be greater than the sped of light. More here: https://arxiv.org/abs/astro-ph/0310808

! Moderator Note You are misrepresenting the simulation hypothesis. You are wrong about the reason (galaxies receding faster than light do not contradict relativity; they are a prediction of relativity). You have presented no rational counter-arguments other than your dislike of the idea. This thread is closed. Do no start another thread on this subject unless you can actually present a logical argument against the actual hypothesis, not your strawman version.

As it says, that is an artefact of the way black holes are defined. There is no actual backward time travel.

! Moderator Note This is a science forum. Unless you are able to support your claims with evidence, rather than just incredulity, then this thread will be closed. ! Moderator Note This is off-topic. It is entirely explained by current cosmological models based on GR. If you want to discuss this, start a new thread. (Also it is not new, the idea is nearly a century old. And the evidence supporting it overwhelming.)

Firstly, the rules require that you do not just post links with no explanation. An interpretation of quantum theory that uses backward causality does not involve anything travelling back in time. It also hard to see how it is relevant to black holes.

In the case of special relativity, most of the evidence and mathematics already existed. The main thing Einstein did was provide an explanation and show how the math could be derived from first principles. In the case of GR, it is more complicated but some math was always there. (But this is off topic. If you want to discuss it further then I suggest you start a new thread.)

Ok. That makes sense. That is just gravitational time dilation: from the point of view of an observer on the surface of the Earth, a clock in the centre runs very slightly slower. But nothing goes “backward” in time, as you seem to be suggesting. The (observable) universe being concentrated at a single point is the conclusion from just naively extrapolating expansion back. In fact, our current physics doesn’t go that far back. All we can currently say is that the universe was once much hotter and denser than now. (And, yes, it was the whole universe that was compressed to a point. The universe is and always has been uniformly full of matter.) White holes can be described mathematically as time-reversed black holes but ... that does not mean that time goes backwards. And there is zero evidence that white holes exist (and good theoretical reasons to think they don’t). I’ll see if I can find something. But most descriptions are a bit exaggerated. We don’t know the answer to either of those. And perhaps never can. A quantum theory of gravity might tell us more. (Some attempts to add quantum theory to the Big Bang suggest that the universe is infinitely old - so it didn’t “come from” anywhere, it was always there). Or the Big Bang could have come from the collapse of an earlier universe.

To highlight this, the radial direction inside the event horizon is the time dimension: the singularity is in the future and us, therefore, unavoidable.

Can you provide a reference for this? There is a big difference between the whole universe being a single point and a black hole. In the first case, the whole universe is compressed to a point and the distribution of mass throughout the universe is always (approximately) uniform. A black hole, on the other hand, consist of a concentration of mass within the universe. The mathematics (and physics) of these two situations are completely different. Can you provide a reference for this, as well. I have never heard. Nothing like it. What is “time regression”? At the event horizon of a black hole time “stops” from the point of view of a distant observer. (Hence the myth of things being “frozen” at the event horizon.) Time does not go backwards. And, from the point of view of someone at the event horizon, it doesn’t even stop.

Then he would have been in violation of the rules if he had posted his ideas here with no math and no evidence. As it is, the math was developed in parallel with the idea and so it was pretty much always testable (his first version of the math for GR actually gave the wrong result). Then that is barely even a hypothesis. As such it does not meet the requirements for this forum. Tough. (You will find that scientists who develop such speculative ideas spend some time discussing it with colleagues, bouncing ideas off others, thinking of ways it might be wrong, how it could be tested etc. They then discard something like 99% of the ideas they have, because these discussions and musings show the flaws in it.) And if there is no way of testing it, then it is not even science. But you could use this forum to ask questions to see if others have ideas how aspects of it could be tested, or if there are obvious flaws that you haven't thought of yet, etc. And if you really have a sound, scientific idea this forum is not really the place for it. This is a general discussion forum for people interested in science (a few of whom happen to be working scientists). It is not really an appropriate place for new theories. (The only reason we have the Speculations forum, in my opinion, is to avoid polluting the sensible science discussions.)

You probably want to read up on the difference between countable and uncountable infinities. For example, if you had an infinitely long line with regular divisions marked on it (every inch or every centimetre, depending what part of the world you are in) then there would be an infinite number of those marks. But between each mark, there would be an infinite number of points. And the infinity of points between each mark is larger (infinitely larger) than the number of marks. Cantor came up with a clever proof of this.

what-about-bob now also banned as yet another sock puppet.

! Moderator Note Sorry, I forgot: No second chances for sock puppets

Particulates are usually defined as PM10 (less than 10 microns), PM2.5 (less than 2.5 microns) and PM1 (less than 1 micron). Cigarette smoke contains particles in all these ranges. So it sounds as if your filters will catch most of these. There will, inevitably, be some particles smaller than this. And the filter will not get all thse within range, for the reasons stated. It is impossible to remove them all. Semiconductor manufacturing clean rooms spend millions on air purification but even at Class 1 (the highest standard) there will be some particulates ate 0.5 microns and below. This requires people entering to wear disposable coveralls ("bunny suits") and take an "air shower" before entering. And definitely no smoking. It can't do any harm to add some plants, as well (as long as they are not toxic!). But I'm not sure it will have much benefit. Maybe you could get an air quality monitor and test the effectiveness?

Here is something about how well irrational numbers (such as Pi) can be approximated by fractions: https://www.quantamagazine.org/new-proof-settles-how-to-approximate-numbers-like-pi-20190814/ As numbers like pi don't "stop", anything expressed using integers (other than an infinite series) can only be an approximation. I assume by evaluating one of the (many) infinite series to that number of decimal places. https://en.wikipedia.org/wiki/Spigot_algorithm Also, surprisingly, it is simpler to calculate the nth digit of pi than all n digits: https://math.hmc.edu/funfacts/finding-the-n-th-digit-of-pi/

I was also thinking of a car analogy while out with the dog!

Firstly, I notice that you have not answered my questions: I asked for how you would measure "electricity" at each end of the wire (not voltage, not current, not phase, not an electric field, but electricity) to demonstrate that it is different. You have not done that. Which is not surprising, because "electricity" is not a thing that can be measured, any more than "physics" or "history" can be measured. I have also asked you to provide references that support your use of the word electricity and you have totally failed to do that either (again, not surprising as your use of the word is idiosyncratic, to say the least). So if I charge a capacitor, with an electric current and then isolate it so there is an electric voltage between the two terminals, there is no "electricity" by your definition because the electric charges are not moving through wires? That makes no sense. The movement of charges is current, not electricity. What differs at each end of the wire is voltage, not electricity. If you say that "electricity is different at each end" it implies that things like the relationship between moving charges and current is different, or that Ohm's law is different. That somehow electricity behaves differently at each end. Here: https://www.google.com/search?q=define+electricity It is about time you presented some support for your arguments, other than just bluster and insults. Do you realise that pretty much the ONLY reason that people are disagreeing with you is because of your inability to communicate in the English language? (That and your refusal to provide any support for your arguments, your refusal to answer questions and your general attitude.)

! Moderator Note One more chance: show your calculations in your next post or this will be closed

! Moderator Note This is a science forum. You need to support your ideas with actual science: mathematics or evidence. Calculate the size of this "scaling" and show that is is a useful effect for magnifying atoms. Otherwise this thread will be closed.

! Moderator Note Moved to Trash. Seems the best place for this sort of pointless rant.

I imagine they are much more effective than plants. There is some evidence that some plants (or, more likely, microbes in the soil) can remove some gases from the air. To some extent. But they probably won’t tackle particulates, which can be a greater health hazard. Especially if you are in an area with a lot of diesel traffic or wood/coal burning.

Unless there are three bodies involved!