pavelcherepan

There's no absolute time, but there is essentially an absolute space in relation to distant stars. So when I said "absolute reference frame" I meant it spatially only. Apologies for confusion. https://en.wikipedia.org/wiki/Absolute_space_and_time#General_relativity

My point is that in GR there's an "absolute reference frame" - the spacetime itself and geodesics that show object's passage through it. As far as I understand, geodesics are invariable, whatever reference frame you calculate them in, the answer should be the same.

Not sure about that. How would you describe a non-inertial FoR in GR?

There's no concept of inertial and non-inertial reference frames in GR. You have flat and curved space-time instead.

For example, an electron-positron pair is created due to quantum fluctuations. They instantly annihilate and produce a gamma ray. It would be moving in a random direction, but with infinite space there will be a significant amount of those that will end up hitting the black body.

I'm not sure if completely empty universe would have quantum fluctuations and it's hardly possible to test it since true vacuum is a theoretical construct and is not achievable. Regardless, I'm pretty certain that fluctuations would happen and after some time the background radiation coming from those would bring the BB into equilibrium with surroundings.

Interesting question. I guess, in this case we have to think of quantum effects. As soon as the BB starts radiating, the previously "empty" space is filled with EM fields. I would expect quantum fluctuations to happen, which would result in some amount of energy going back to the BB and then eventually it will reach equilibrium with the surroundings and stop radiating. It will be extremely close to absolute zero, but it won't radiate indefinitely.

In GR there is no concept of inertial FoR, but it has curved space-time and you would either be rotating relative to your local geodesic or moving on a closed geodesic. In ether case it should be absolute. P.S. There's actually a wiki article on Absolute rotation. https://en.wikipedia.org/wiki/Absolute_rotation

I tend to believe that the Universe is infinite, but what I believe doesn't matter. We can observe only a chunk of the entirety of the universe with large but finite amount of mass and energy. As for 0 K, yes, it can't be reached in principle, but we can get within some hundred billionths of a degree to it using lasers. You can look at it in other way. For example, we have an object and it radiates "infinite" amount of energy via black body radiation. We heat it up by X Kelvin. The amount of energy radiation is still an infinity. Therefore, where did the energy we just added to the system go?

Nope. That's why I specified 0 K. There's no black body radiation at this temperature. And we know exactly what amount of energy we put into making an object radiate. Therefore when see infinitely high amount of energy coming off, but we've just put in 1000J, then where did the rest of the energy come from? That is not to say that the notion of infinite energy is not absurd in its own right.

Simply put, it violates energy conservation. Take an object close to 0 K, now provide it energy to heat it up to 1000K. You know exact amount of energy that went in, and if your calculations show you that it should radiate infinite amount of energy, end don't meet.

Inertial frame is a frame that moves at a constant velocity without acceleration. On the other hand, rotation (or for that matter any motion on a closed trajectory) has to involve acceleration. Therefore, any FoR that exhibits such motion is not inertial by definition. When you are in a rotating FoR you can, in principle, measure the acceleration due to rotation. One such example is the Coriolis force or Coriolis effect. https://en.wikipedia.org/wiki/Coriolis_force

No. What you are talking about are great mass extinctions, but even without those species die off all the time. It's just that during mass extinctions it's much more obvious. Mammal species, for instance, exist only for about 1 million years on average before going extinct. It's just a normal part of evolution. https://en.wikipedia.org/wiki/Background_extinction_rate OK, I might not have worded my original comment correctly in this regard. Or other way around - predator populations linked to lemming population cycles. For example, this study tends to disagree with you: Or extensive grazing results in inhibition of some proteins , or amount of snow cover , or changes in reproduction rates. In fact, it's still a controversial topic, in large part due to the lack of large-scale controlled experiments. And it's most likely not due to one single cause, but to combination thereof. P.S. By the way, Wiki article that you linked doesn't say what you say it does. Instead:

Take lemmings as an example with their regular spikes and drops in population. Whenever conditions allow, lemmings start to breed at extreme rates and quickly overwhelm ecosystem's ability to support so many of them, which then results in starvation and death of majority of the population only for that to repeat a few years later. Thankfully, humans have developed technologies, which allow us not to die off in spectacular fashion every few years. That's doubtful. If all animals were self-sufficient and always living in perfect harmony with their habitat, species wouldn't tend to go extinct as often as they do based on geological record. Well, then don't describe humans as super-primates. I see no reason why you would do so. Primates and humans are not just separate species, they are even in separate genera.

That's the whole reason I started this discussion. There is obviously something wrong with my reasoning and I want to know what it is. Indeed, the Schwarzchild radius of the BH will increase somewhat. If we take a 2-solar-mass BH, the radius of EH will be 5932.(4) m, but if we throw in a 100 kg object, it will increase to 5932.44444444444444444444444459. Then, if the measurable extent of space-time curvature caused by this 100 kg object prior to falling into the BH is greater than the difference between these numbers, we should still be able to detect it as being outside EH, regardless of its expansion. And this would still result in "duplicating" the object's mass-energy. I'm very confused.

Thanks everyone for your inputs. Now can we please look into the conundrum I'm looking at. I think I shouldn't have brought infinity into question, it will be easier without it: 1) Object falls into a black hole 2) After a finite time it reaches singularity and its mass is added to the mass of BH 3) In EM spectrum we should still be able to see it stuck just above EH. We can't see into BH, so there is only one copy of the object in the observable universe in EM spectrum. 4) If, like MigL commented, gravitational information is subject to the same time dilation as any other information, we might still be able to measure space-time curvature of the object outside EH 5) Then we have "two copies" of the object's mass-energy in the universe. One being a part of BH mass and the other causing curvature outside EH. How is that possible?

Visibility aside, I'm still more interested in gravitational effects on the curvature of space-time from the body.

But as far as I understand the photons emitted close to EH will get more and more red-shifted and if we use something like a Penrose diagram for illustrative purposes, then final light will arrive infinitely far in the future. OK, this makes sense, but let's assume we're dealing with very lonesome BH that's not feeding on anything, except CMB and its event horizon is expanding extremely slowly.

Ok, but then an infalling object will have increased the mass of the BH. So in this case we'd have once "copy" of the object that became a part of the BH and another just hanging out at the event horizon? This doesn't happen with EM radiation, because we simply can't see the object inside the BH, but gravitationally it would then appear to have created duplicates. This is what confuses me the most.

So "they" have observations that confirm mathematical models and you have your "belief". It's a lousy science critique, when your critique is coming from non-scientific domains. One of the properties of an orbit is that it's always convex towards the central orbiting body. In the case you described, orbits will be in many cases concave. Also, as stated by other people, your beliefs don't matter in a scientific discussion and you don't have any arguments to support your position except you believe it to be a fallacy.

Say we have an object falling into a black hole. As it approaches the even horizon external observers who are farther away from EH than the object in question will see it slow down and get progressively red-shifted the closer it gets to EH. Then finally, the from the perspective of the object it will cross the horizon, but all external observers will disagree, as they will see it forever stuck just above the EH. The object will go more and more dim, but as I understand, with an infinitely sensitive devices, external observers should be able to observe it being stuck at the same spot indefinitely. Is that correct? Now, the object, before venturing on this one-way trip would have had a mass and energy and would cause the local space-time to curve, however small that effect might have been. So the question is: if my previous statements were correct, we should be able to observe electromagnetic radiation of the object as being stuck above EH indefinitely, but would we be able to observe the curvature of space-time corresponding to that object in that same location?

Well, chemical properties of an atom are all related to the valence electrons and in turn the configuration of an electron shell depends on the number of protons in the nucleus. Note, number of neutrons in the nucleus doesn't affect chemical properties much which can be seen from different isotopes of atoms participating in the same chemical reactions with the same results. I'm not an expert on this matter, but in modern understanding nucleus is not just some different colored balls attached to one another as it's often portrayed. Instead, the nucleus is a 'soup' of mostly two flavours of lighter quarks (up and down) with gluons zipping around between those. Quarks regularly change flavours and it's all very complex. Now to your question - usually a nucleus can have more of fewer protons than needed is either by simply being created that way, possibly as a decay product of another radioactive nucleus; it can absorb neutrons coming off of another nucleus which is how nuclear fission works or it can even be created by clamping together couple lighter nuclei as in case of fusion. As I said before, there's little differences in terms of chemical properties between isotopes as they all have exactly the same electron configuration.

Interesting. If that were true, it would have large implications in general cosmology as lambda-CDM model was based on observation of Ia supernovae. This is a big can of worms to be dealt with.

Here's the quote from wiki page on brown dwarfs: https://en.wikipedia.org/wiki/Brown_dwarf The size, though, will be more or less the same as the Jupiter, which is as I understand is more or less as big as a gas giant can get. After that it won't increase the size much, just will become more and more dense. Even smaller M-class red dwarfs like Proxima Centauri are only ~20% larger than Jupiter in size. Not sure about 3He though.

Well, I guess, if plant photosynthesis had increased in efficiency, the said plant should produce more sugars, have faster growth and more CO2 absorption. We could then solve world hunger issues and also quickly reduce the amount of CO2 in the atmosphere . In which case we wouldn't even need to stop burning fossil fuels! Yay! Everyone wins! Not sure how it can be done though.