First of all, kruskal coordinates show beyond doubt that the event horizon is just a regular null hypersurface that the observer wouldn't notice crossing locally. (Of course if you look around, at the moment of crossing into the event horizon you see everything else that was falling into it unfreeze and continue crossing).
If you want to take into account the evaporation of the black hole, then you should look at something like the vaidya metric. The mass function is a function of the ingoing Eddington coordinate v, which takes on a specific value when you cross the event horizon, and so you observe the black hole at a specific mass as you cross the event horizon. Contradicting your layman understanding of time dilation for the observer relative to the black hole.
Once you cross the horizon, the r coordinate becomes timelike, and so you are forced to move to decreasing r value just like a regular observer is forced to move to increasing t value. Your entire future, all your future light cone is within the black hole and it all terminates at the singularity. Minewhile, the t coordinate is space like which is what gives you space like separation from the mess that had happened in the original gravitational collapse. You wouldn't be blasted by a frozen supernova like you have said.
You can kind of say the universe splits at the event horizon, the time like coordinate changes from t to r and the future of the black hole branch of the universe is permanently cut off from the rest of the universe.
In rotating and charged black holes it is different, and you observe the evaporation of the black hole once you cross the Cauchy horizon. If the black hole is eternal (because someone kept feeding radiation to the black hole, maybe by reflecting the hawking radiation inwards), then you would in fact see timelike infinity as you reach the Cauchy horizon, so this time like infinity is quite physical. You would need to avoid being vaporized by blue shifted incoming radiation.
The ordinary Schwarzschild metric diagram in that article makes it crystal clear that in-falling observers asymptotically approach the horizon, but never cross it.
Read the next section as well, which uses the "Tortoise coordinate"... which again uses the mathematical infinity to allow the horizon to be crossed.
I really don't understand why people keep arguing about this!
If you find yourself writing an infinity symbol, you've failed at physics. Stop, go back, rethink your mathematics.
You can choose stupid coordinates that introduce a singularity wherever you like, in GM or in classical mechanics just the same. The coordinates have no meaning.
> Of course if you look around, at the moment of crossing into the event horizon you see everything else that was falling into it unfreeze and continue crossing).
Is that so? Isn't that a continuous effect? Things falling into the black hole appear to be frozen at the event horizon only for an observer at infinity.
Before invoking parallel universes, how about comparing the system to nature's mind-boggling number of particles in the macroscopic world?
A single gram contains 10^23=2^76 particles. Google's random circuit sampling experiment used only 67 qubits, Which is still order of magnitude below 76. I wonder why, the chip had 105 qubits and the error correction experiment used 101 qubits.
Did Google's experiment encounter problems when trying to run RCS on the full 105 qubits device?
Before saying that the computation invoked parallel universes, first I'd like to see that the computation couldn't be explained by the state being encoded classically by the state of the particles in the system.
Somehow the universe knows how to organise the sand in an egg timer to form an orderly pile. Simulating that with a classical computer seems impossible - yet the universe "computes" the correct result in real time. It feels like there is a huge gap between what actually happens and what can be done with a computer (even a quantum one).
It's a good questiopn why that is so. But I wouldn't draw from that the conclusion that Universe somehow "calculates Pi", and then puts it in all the forces it "has" so it turns out in our formulas. That is rather fantastical way of thinking and I do see its poetic appeal. A bit like "God doesn't play dice, or does he?"
What is calculation anyway we may ask. Isn't it just term-rewriting?
Pi is just a description used for calculating perfectly/near-perfect spheres. A sphere is nature's building block, since every point on it's surface is the same distance from the centre.
> yet the universe "computes" the correct result in real time
Does it? In what sense the result is "correct"? It's not because it's perfectly regular, or unique, or predictable, or reproducible. So what's "correct" about it?
Completely out of my depth here, but maybe there is a difference between evolution of a physical system and useful computation: and maybe there's much less useful computation that can be extracted from a physical system than the entire amount of computation that would be theoretically needed to simulate it exactly. Maybe you can construct physical systems that perform vast, but measurable, amounts of computation, but you can extract only a fixed max amount of useful information from them?
And then you have this strange phenomenon: you build controlled systems that perform an enormous amount of deterministic, measurable computation, but you can't make them do any useful work...
It does seem to, and can anyone credibly say they aren't out of their depth in these waters? (the sandpile thing is not original, it dates back many years). Taking the idea that the "universe is a simulation" [0], what sort of computer (or other device) could it be running on? (and how could we tell we're living in a VM?)
From the same school of thought, to simulate the path of a single particle seems it should require a device comprised of more than a single particle. Therefore, if the universe is a simulation, the simulator must have more than the number of particles in the universe.
> Somehow the universe knows how to organise the sand in an egg timer to form an orderly pile. Simulating that with a classical computer seems impossible
Is it really?
There's only ~500,000 grains of sand in an egg timer.
I don't know anything here, but this seems like something that shouldn't be impossible.
Maybe it's not that hard to simulate, but let's start with looking at just two of the sand grains that happen to hit each other? They collide, how they rebound is all angles, internal structure, Young's modulus, they have electrostatic interactions, even the Van der Walls force come into play. Sand grains aren't regular, consider how determining the precise point at which two irregular objects collide is quite a challenge (and this isn't even a game, approximations to save compute time won't do what the real world does 'naturally').
So while we can - for something as simple and regular as an eggtimer - come up with some workable approximations, the approximation would surely fall short when it comes to the detail (an analytical solution for the path of every single grain).
A close approximation should arguably include collapses/slides, which happen spontaneously because the pile organises itself to a critical angle; then an incredibly small event can trigger a large slide of salt/sand/whatever/rocks (or whatever else the pile is made of). Even working out something like "What's the biggest and smallest slides that could occur given a pile of some particular substance?".
Every approximation will by definition deviate from what really happens - I suppose that's why we talk of "working approximations", i.e. they work well enough for a given purpose. So it probably comes down to what the approximation is being used for.
There is the idea that we are all living in a simulation; if so maybe if we look closely enough at the detail all the way from the universe to atoms then we'll start to see some fuzziness (well, of course there's quantum physics....).
When the output looks the same as the original we would say that the simulation was successful. That is how computer games do it. We're not asking for the exact position of each grain, just the general outline of the pile.
An image of something is likely to be the simplest model of that thing that happened, and it has A LOT less information than a 3D model of arbitrary resolution would have.
Simulation is never an "image". It may simulate each grain, just saying it doesn't need to simulate each precisely, because the law of large numbers kicks in.
This is the basis for example Monte Carlo simulation, it simulates real world with random numbers it generates.
Every video game engine is a simulation and many of them are a very simplified model of images of things happening instead of simulating the actual physics. Even "physics" in these engines is often just rendering an image.
The real issue is that the sand isn't orderly sorted. At a micro level, it's billions and trillions of individual interactions between atoms that create the emergent behavior of solid grains of sand packing reasonably tightly but not phasing through each other.
> I wonder why, the chip had 105 qubits and the error correction experiment used 101 qubits.
I wonder why, byte has 8 bits and the Hamming error correction code uses 7 bits.
oh right - that's because *the scheme* requires 3-7-15-... bits [0] and 7 is the largest that fits
Same with surface error correction - it's just the largest number in a list. No need for conspiracies. And no connection to manufacturing capabilities, which determine qubits on a single chip
You learn a lot by what isn't mentioned. Willow had 101 qubits in the quantum error correction experiment, yet only mere 67 qubits in the random circuit sampling experiment. Why did they not test random circuit sampling with the full set of qubits? Maybe when turning on the full 101 set of qubits, qubits fidelity dropped.
Remember macroscopic objects have 10^23=2^76 particles, so until 76 qubits are reached and exceeded, I remain skeptical that the quantum system actually exploits an exponential Hilbert space, instead of the state being classically encoded by the particles somehow. I bet Google is struggling just at this threshold and they don't announce it.
The universe is not inside a black hole. Inside black holes the radial coordinate is time like, which is definitely not true in our universe, where the time coordinate is timelike, and the radial coordinate is space like.
Inside of black holes looks nothing like ordinary spacetime. Inside black hole, everything in your future is with decreasing radial coordinate, which means space is shrinking until you hit the singularity where radial coordinate is zero and you have no future.
No, this depends on your choice of coordinate system - has been debunked N times on physics reddit in virtually every thread that it comes up. The EH itself is not a singularity in the observers reference frame as they cross it nor do they particularly notice when they do.
I never said EH is a singularity. I said you could notice you're inside as your timelike coordinate becomes the radial coordinate. That's something you could easily notice if you look around, it would correspond to a shrinking universe, and our universe is expanding.
The "you won't notice crossing the event horizon" troupe is true only in a very local sense. If you move around and observe the geometry around you, you can definitely tell you're inside a black hole.
As the black hole getting larger, it is more difficult to notice this difference (of crossing the event horizon or “observe the geometry around you”.) and as we are talking about the whole visible universe being inside a black hole, we are in this extreme large scale.
Also, I’m not sure why you’re arguing about the radial coordinate being time-like. You can only measure in your own local reference frame. You wouldn’t necessarily be able to transform between your own local reference frame to the blackhole’s if you don’t know you’re in one.
The fact that radial coordinate is timelike inside the event horizon doesn't change when you change coordinate systems. The radial direction remains timelike in kruskal coordinates. Direction being space like or time like is independent of coordinate system.
I think for this to be a complete explanation, it needs to be shown that what was "the time" coordinate is not expanding in some sense.
Does volume even make sense in GR?
Thought experiment here would be: suppose me and you appeared stationery (from the point of view of the outside reference frame) just above the horizon of a non-rotating black hole in the manner of Boltzmann brains. We immediately start falling and cross the horizon. Now will you see me receding from you or going at you? Will I be red-shifted or blue-shifted?
Love this game. I abused multiple tabs as a way to save the current game, as opening new tab copies the state of the game, and got to a high score of 150,000 (I could keep going, I didn't lose) and made a 4096 tile. Using multiple tabs to save the game when you get a good position makes it possible to play indefinitely. It's even more addictive when you can save the game because then it's not really over at game over.
Our profits margins are lacking, please do force some artificial scarcity so we get some of our power back after the competition in our field eroded our power!
Notice how every suggestion for fighting climate change always involves preventing new oil competitors from developing while doing nothing about existing oil fields?
They are laughing all the way to the bank as they know the world depends on them and can't possibly detach that dependence, renewables barely make a dent in that. They don't care about total oil consumption only profit margins.
There’s nothing artificial about the budget of carbon emissions we have before each temperature increase is bought. Increasing the cost of fossil fuel is a good way to make alternative energy more appealing to investors
... fossil-fuel subsidies rose by $2 trillion over the past two years as explicit subsidies (undercharging for supply costs) more than doubled to $1.3 trillion ...
Our analysis shows that consumers did not pay for over $5 trillion of environmental costs last year. This number would be almost double if damage to the climate was valued at levels found in a recent study published in the scientific journal Nature ...
I'm not defending our irresponsible Co2 emission behavior in any way, and this only applies to a part of your link, but I feel calling negative (future?) externalities "government subsidies" is simply dishonest reporting.
I'd also argue that this framing is actively harmful, because it perpetuates the view that "big government" and "big oil corporations" are mainly to blame for lackluster action, but the inconvenient truth is that the average western citizen just does NOT want to sacrifice neither vacation air travel nor personal car, nor is he willing to pay more for energy/electricity.
Government action (or lack thereof) mainly mirrors this popular sentiment-- its not a big lobbying conspiracy...
If the government knows about those negative externalities, and chooses not to prevent or tax the behavior, but instead subsidizes that sector, how else would you describe it?
> "big government" and "big oil corporations" are mainly to blame for lackluster action
If one government takes action, those actions often get reversed within a few years. The issue isn't just one specific government; it's the system itself. Critics argue that neither capitalism nor communism can resolve this, but they're not the only systems possible.
The real culprits include the growth imperative in our financial system, politicians' focus on short-term actions at the expense of long-term vision, the slow adoption of renewable energy, and subsidies for harmful sectors decades after their impacts are known, etc.
We have only a few years/decades to reverse the effects of past actions; after that point, they'll become irreversible. We're in the overshoot for 50 years at this point, after all.
Blaming one political side or the other doesn't solve the issue. We must tackle problems like climate change, pollution, biodiversity loss, overfishing, inequality, and the need for Universal Basic Income/Services across multiple fronts.
We need a Great Reset/Rewrite; otherwise, we should brace for a Great Simplification.
> If the government knows about those negative externalities, and chooses not to prevent or tax the behavior, but instead subsidizes that sector, how else would you describe it?
E.g. as "negative externatilites that were not appropriately taxed".
Because "subsidies" implies tax dollars being spent to deteriorate the situation, while the reality is basically the reverse.
And it is VERY obvious that this doesn't simply happen because "big oil" did so much lobbying that the government misrepresents the will of the people-- voters were visible in favor of subsidies and lower fuel prices (especially blatant during Ukraine-price spikes in Europe).
Just picture running on a "100% fossil fuel taxation to be spent on improved public transport" platform-- what country you think would elect that right now? Much less re-elect...
> We have only a few years/decades to reverse the effects of past actions; after that point, they'll become irreversible.
I disagree with this viewpoint: I think long term consequences are already completely inevitable, any current and future actions are only gonna change the exact magnitude.
> I think long term consequences are already completely inevitable
Degradation vs. collapse. Collapse is still preventable, but the window is closing fast.
If we'd stop fossil fuels, reform agriculture and reforest what we can, we'd be able to reverse the warming and let biodiversity rebound. Continue for a few more decades, and the carrying capacity falls drastically.
I don't buy into that at all; massive waves of climate refugees, environmental disasters, loss of coastal urban space, economical crises: sure-- but collapse of civilization?! I simply don't see that happening, to me that appears like completely unfounded pessimism.
I was referring to the collapse (significant degradation) of the environmental carrying capacity. In such a scenario, our civilization would implode on its own.
It's a complex topic ... I only can give you a few links. The system we live in is very complex ... and as in every complex system even a minor error can cripple the system. Just remember how much damage to the economy was caused by just one ship blocking the Suez.
I don't think the system is able to handle large-scale agricultural failures, prolonged droughts or abrupt sea level rises. Everything seems to be changing more rapidly than predicted - from air and sea temperatures to thawing, droughts, biodiversity loss, etc.
Exactly, fuel should be more expensive because the negative externalities of its consumption should be priced in.
The extra value extracted from pricing in those externalities should be directed by the state towards offsetting the damage, it shouldn’t just be pocketed by the companies causing the damage.
The problem is that we no longer have the time to let market forces work that slowly. Things like home heaters, stoves, vehicle engines, etc. have service lifespans measured in decades so we need everyone buying electric now. Things like EVs or heat pumps often have higher upfront cost so we need to stop having the situation where people feel like they have to pay more to do the right thing because the fossil fuel prices are subsidized so low that many people don’t feel much pressure to change.
That's a valid concern and is the reason to scale the tax in over a many year period. That tax revenue doesn't have to be consumed by a swelling government, but part of it could be directly distributed as a dividend to each member of the society on an equal per-capita basis or biased towards lower income members of the society.
The counterfactual challenge is brutal, too: if we don’t do anything, the impact on food production will be far worse but if we don’t let it happen first we’re going to be plagued with people saying it wouldn’t have been so bad.
To clarify, we've been minimally subsidizing clean energy while not only significantly subsidizing oil exploration and development, but also using the largest military + intelligence budgets (US, UK) to "stabilize" oil producing regions and transportation.
I don't believe Avi found
aliens, and I don't even think finding aliens in our neighborhood is likely or will ever happen.
With that being said, it takes balls to come up with such claims, and you need people arguing passionately against the mainstream opinion in any subject to properly judge what is the truth.
A cautious position that is afraid to lay out the entire arguments and claims just won't do. And I don't even believe what he says - but I do believe that it is important for devil's advocates to fully embrace their position instead of chickening and trying to be cautious with evidence. (up to the point where the evidence really does contradict their position).
And I fully believe him when he says he's bullied, and the other subtext I see in her question is that she envies him of his courage. Of having the balls to stand up for the subject that despite 40 years, she still has self doubts about.
He doesn't seem nice or polite. But honestly, I can totally get why he's pissed off. She did not have the balls or courage to fight for her position with all that it takes, and instead of being glad someone else has the courage she was lacking, she attacks him.
And even tho I don't believe him, I think having people with courage to stand up and argue against the consensus is incredibly important. Just like you need lawyers on both sides in litigation, it's not enough to just collect evidence. She did not advocate for her position for 40 years. She did collect evidence but that's not enough.
It does not take "balls" to speculate wildly. Any grifter can do it, whether they have a uterus or not. Sensationalism is always easier than evidence-building.
> I think having people with courage to stand up and argue against the consensus is incredibly important.
I agree it would be nice if Loeb tried that. So far he hasn't made any arguments, just bloviated.
And what "consensus" do you imagine Loeb is your champion against? Tarter is a pioneer carving out a new discipline, not the latest head of some ancient SETI cartel started by Aristotle. Any "consensus" is tentative at best. To hear Loeb speak, you would think it were he who started searching for techno-signatures forty years ago--with Tarter in a dominatrix outfit and a whip waylaying him at every step.
He yelled over her, refused to let her speak, misrepresented her arguments, and tarred a diverse research community with a broad brush. Nobody made him show his own ass on Zoom. That was his choice.
By contrast Tarter was polite, gracious, and statesman-like. She defended her colleagues clearly and let the clown dig his own grave. Never interrupt your enemy when he's making a mistake. If I were one of the researchers she were defending, I would be proud to have her up there representing me, and certainly glad I wasn't the one who was asked to find time in my research schedule to act as some narcissist's punching bag for an hour so he can build his social media viewership.
Loeb is just another science grifter who pumps up bad ideas with hot air in order to make some post-truth money off rubes who watch Joe Rogan--where making wild and evidence-free claims made with a flourish of performative masculinity beat decades of careful research.
First of all, it does take balls. Look at the response he's getting - he is ridiculed, flamed, called a grifter, and bullied. And he put his reputation as a professor and academic on the line. He had risked his career to do this.
AFAIK he did make some arguments about both oumuamua and those other interstellar objects. His claims aren't "evidence free". He has insufficient evidence and I'm not convinced, but without people willing to pursue evidence out of their comfort zone, science can't make discoveries.
Despite 40 years of research, Tarter risked nothing. She never put her reputation on the line. Neither did her colleagues. You can't get funding for something you yourself aren't willing to take risks on. Their cautiousness and lack of confidence and aversion to taking personal career risks reflects on their own confidence in the subject, and any person that would've considered funding them reads those signals and acts accordingly.
He's the first to have taken a personal risk, and taking a personal risk is the only way to convince others to follow you with monetary risk. "performative masculinity", also known as having balls and self-confidence and taking personal risks, is a precondition to getting others to follow you because you can only lead by example. Women can do it just like men - but it is usually a masculine trait.
If you're a feminist and you still don't get how men are more successful in some areas, you could cry about masculinity, but maybe you should learn from them that what it takes is taking personal risks and leading by example, and getting over your personal risk-aversion. And if you can't grow some balls and get over your personal risk aversion, at least have the decency to appreciate those taking personal risks to further a common cause. How the hell is Loeb her enemy in your twisted mind?!
For every man you see at the top, there are 10 men at the bottom whose personal risk failed. Most likely, Loeb will be one of them. I'm actually going to bet on that. While Tarter will continue with her comfortable job with mediocre funding, or maybe bigger funding thanks to Loeb. He'll be the one with a ruined career, not Tarter. So easy to cry "toxic masculinity" when he's in the spotlight, lets see whether Tarter will wish to swap places in 10 years after he's failed. Then tell me with complete honesty which action was the harder one to do.
That's exactly toxic feminism. Pure envy towards the men taking the risks that you couldn't muster the courage to take. Next time, take the risk yourself or be grateful to those that have the courage to take risks that benefit you. Women can be just as brave, look at Greta Thunberg. I don't believe her either by the way (you can look my post history about climate change), but she did have more effect than many "evidence-builders" and she also took a greater risk, and I appreciate that.
You're the one who's instinctual association was to a dominatrix. It's your viewpoint of oppression and domination that's clouding your judgement.
Maybe one day we'll live in an AI supported paradise and you won't need to take risks.
Until we get there, it's going to be men's shitty role to take risks. I appreciate everyone who takes risk, men are just programmed for it.
And they need this dumb incentive carrot at the end. They need to see those few men at the top who made it to want to take their risk. You shouldn't hate them for it.
You have one sperm out of millions reaching the egg, while the egg's risk is that nothing will come. Until our society devolves into the women artificially inseminating themselves while being supported by robots in paradise, the real risk to society is that men stop taking risks. The least you can do is have some compassion for the fools.
GameStop? that wasn't a bubble, everyone buying it knew fully well that there are no fundamentals and that they are buying it to cause a short squeeze on hedge funds who shorted too much stock. Some of them got huge gains, others kept chasing the trade after it was over.
But it definitely wasn't a bubble. It was a good trade and there were some FOMO losers who kept chasing it more than they should.
You know what actually needs an investment? Climate models which are completely shit right now. It's actually preposterous that there are trillions of dollars worth of decisions in ESG and climate credits and government incentives while the science behind this is supported by old fortran code that has terrible quality and can't give reasonable predictions.
We have trillions of dollars chasing predictions of code barely worth a million dollar investment. That's absurd, it's a recipe for disaster.
Instead of useless government beaurocrats shuffling hypothetical CO2, should invest in climate models that aren't patched together by grad students in universities and old as hell code and a few NASA engineers maintaining an untested unreadable and unverifiable monstrosities.
Maybe there's no crisis at all. Maybe it's all doom and gloom, but the certainty that everyone's pretending that science gives is just not reflective of the reality of how climate models look right now. They are absolutely shit and I don't blame them given the resources they have, they did their best, but it's absolutely insane how much money is moving around on predictions coming out of that mess.
Say more about this! Let's say you had $100B to build better climate models over the next 5 years. Where would you spend it?
My general sense is the models are good enough to tell us that a) things are headed in the wrong direction and b) we're really far off from a solution. Generally in agreement with you but I haven't researched deeply about what's needed on more modeling and how to prioritize.
You need at least two completely independent teams who don't see each other's code so you'll have a rough idea how much developer bias is responsible for the signal. Right now they are all copying code from each other, a single error in these and all the climate models are effected. Replication here should mean different scientists writing different code arriving at the same estimates.
It needs to be open source, and it needs to be way more organized, no physical constants which aren't constant or which have bad precision or which have different values in different parts of the code.
Actual error modeling built in or at least a way to measure and quantify the accuracy.
Some models only use CO2 input for radiation and not for many other parameters that depend on CO2. Because the code is a mess and constants that shouldn't be constants are all over the place. And getting "constants" right is even more important than having high resolution to the simulation.
Getting real physical data to replace all the ad hoc constants is extremely important. And validating the correctness of the cloud modeling with real world data is also important.
And you can't write huge spaghetti code, it needs to be readable and comprehensible to someone other than original programmer so that people can validate the assumptions.
I think you need an expert team of software engineers, physicists and climate experts that will either build good climate models or decipher the mess that is the current models variability.
Honestly, looking at the code of some models I don't think there's much hope in understanding them to the point where you know where the deviations are coming from, it's probably easier putting together new models that are subject to much more strict testing, unit testing, evaluations against real world data than salvaging the current mess. And just throw out the models which fail the testing.
If you want to take into account the evaporation of the black hole, then you should look at something like the vaidya metric. The mass function is a function of the ingoing Eddington coordinate v, which takes on a specific value when you cross the event horizon, and so you observe the black hole at a specific mass as you cross the event horizon. Contradicting your layman understanding of time dilation for the observer relative to the black hole.
Once you cross the horizon, the r coordinate becomes timelike, and so you are forced to move to decreasing r value just like a regular observer is forced to move to increasing t value. Your entire future, all your future light cone is within the black hole and it all terminates at the singularity. Minewhile, the t coordinate is space like which is what gives you space like separation from the mess that had happened in the original gravitational collapse. You wouldn't be blasted by a frozen supernova like you have said.
You can kind of say the universe splits at the event horizon, the time like coordinate changes from t to r and the future of the black hole branch of the universe is permanently cut off from the rest of the universe.
In rotating and charged black holes it is different, and you observe the evaporation of the black hole once you cross the Cauchy horizon. If the black hole is eternal (because someone kept feeding radiation to the black hole, maybe by reflecting the hawking radiation inwards), then you would in fact see timelike infinity as you reach the Cauchy horizon, so this time like infinity is quite physical. You would need to avoid being vaporized by blue shifted incoming radiation.