I think this says less about cosmology and more about the incredibly effectiveness of the standard model in the regime we can test directly on earth.
If we compare ΛCDM to most other scientific theories it doesn't look so bad in terms of discrepancies. Certainly there are many unexplained effects in solid state physics, there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to a wall and that's an experiment you probably did as a child.
I had to look that up. Here's research[1][2] from 2019 about "why ice is so slippery", including some of the apparent surprises. I dunno. I'm not a physicist so some of the surprises seem like very minor things to me.
Spoiler: According to this research, ice is slippery because of a thin layer of water. (As we expected, no?) But the water layer is 1) thinner than expected, 2) more viscous than expected, and 3) contains bits of ice which help make it extra slippery.
> "Usual explanation is completely incorrect."
Only for an unusual definition of "completely" IMO. Again, IANAP.
Exactly, this it’s the new research. Standard (incorrect) explanation is because ice melts because of the pressure from the object put on it. Robert Wood showed it to be untrue at the beginning of the twentieth century, but “popular scientists” didn’t get the memo.
> Only for an unusual definition of "completely" IMO.
Agreed. While the "usual explanation" may lack the details that actual testing provided, deduction and logic in this case were pretty much harmonious with the findings. The water layer being thinner or more viscous than expected doesn't invalidate the basic assumption, and that's where all science starts, right? Some basic, yet to be disproved* assumption.
Maybe the ice molecules move through the water with less resistance, since the ice molecules are already 'tied up' in a lattice structure and therefore do not form as strong of hydrogen bonds with the neighboring water molecules.
That's just because your skin has water molecules that freeze on contact with the ice cube. If you use tongs to put an ice cube on your desk, it doesn't stick at all, right? And the friction is very low so it's easy to kick away -- things like a leather wallet stick much better to your desk.
I remember listening to joe rogan when he interviewed neil degrasse tyson and he had some fascinating insights into the behavior of water with relation to pressure and temperature.
I can imagine ice on an iceskate wanting to be solid, but because that takes up too much space it becomes a liquid instead.
The usual hypothesis is that a microscopic layer of the surface melts, not because your shoes are warm, but because of the pressure. But the pressure is not enough to do that.
That said, as anyone who has been in icy conditions can attest, it is clear that ice at ~0° C is vastly more slippery than at, say, -20°C.
My understanding is that, at the borders, master is constantly changing between its states. A boiling pot has water molecules turning to steam, as well as vice versa. It just has more of the first probabilistically.
That's more or less it, as far as I understand. There's the hexagonal lattice of solid water ice, where hydrogen bonds form a 3D tetrahedral structure which is very stable. At the boundary, there are no molecules "above" the solid latice, so those water molecules are held less tightly. The exact dynamics are challenging to predict because we can't exactly see what's going on (most simulation based).
The pressure from well distributed static load divided by area is not, but on the tiny scale where the difference between grippy and less grippy surfaces happens there isn't so much "well distributed" going on. And once you add lateral force to the mix all bets are off: there will always be a point getting better grip (is surface interference the correct term?) than others, see a local force concentration and when that causes a tiny spot of phase transition there will very soon be a new point of least local slippyness getting all the attention of lateral force.
", it is clear that ice at ~0° C is vastly more slippery than at, say, -20°C."
There is nothing more slippery in my experience, than rain on the street, that just turned frozen. But ice at -20°C is usually older and has not such a smooth surface anymore, so hard to compare in non lab settings.
If that were the case, then cold things wouldn't slip on ice, but they do (for a demonstration, pick up a rock that's been sitting out in the cold and note that it still slides on ice)
I'm not sure a cold rock sliding across very cold ice will slide any better than if the ice was another very large smooth rock. Ice is hard and smooth. Hard smooth things have low friction.
My favourite example of the intractabilities of some theories is that magnetohydronamics apparently can't predict the formation of streamer jets when you put your finger on a kid's plasma ball – i.e. the main point of the toy is beyond the most advanced theory that lies behind NIF, JET, ITER, etc...
I don't think I've ever, out of all my physics classes up to grad seminars, been given the impression we have everything figured out. In fact, it was hammered into us that all we have are "effective" theories, at least when it comes to high energy physics, and that's not even talking about grand unification (electroweak + strong force unification), let alone Theory of Everything (electroweak + strong + gravity).
Maybe not where you studied, or at the level you studied, but in upper division undergrad physics at a top tier California school I definitely was given the impression that I should just crunch the numbers and not think too much about how it might be working.
Was this a quantum mechanics class? Thinking about how it might be working leads to strange things like the Many-Worlds Theory[1] and other very weird ideas. "Shut up and calculate" is the usual method of dealing with these deeper questions.
So much this! There’s surely a huge argument that all of scientific education is a massive disservice.
The point should be to learn and appreciate the method or process of scientific investigation of uncertain and mysterious or hard to understand phenomena.
Instead we get dogma as a proxy of measuring intelligence with little regard for what the fundamental tools are of being a scientist.
I’ve gone all the way through to Grad School and came out astounded at just how little commitment to or a sense of the essence of scientific investigation and what’s expected of the investigator there is in the system. They don’t prepare you for it because they themselves weren’t prepared. You can try to leverage some meta understanding of the “process” in conversation or debate, but so often the conversation falls flat because few are prepared or accustomed to it. Research is often done, IMO, in philosophical poverty by people eking out a living in the gutters of novelty and paradigmatic safety, averting their gazes from the sky (flourishes aside, you get my point).
Putting aside the health of actual research. If the general public is to benefit from education and pass that benefit into their society (that’s the point right), it needs to be more than soon to be forgotten and often useless fallacies.
> There’s surely a huge argument that all of scientific education is a massive disservice.
> If the general public is to benefit from education and pass that benefit into their society (that’s the point right), it needs to be more than soon to be forgotten and often useless fallacies.
I realize this is hyperbole, but still I think it's obvious that there is more than soon to be
forgotten and often useless fallacies.
I do generally agree though that current models/paradigms are usually presented more as "the final word" vs "a useful mental model".
Esp. when paradigms are challenged by, or conflict with untestable traditional explanations, ppl tend to get irritated and overstate the confidence of their own understanding
Agree. I’m guilty of descending to hyperbole at times!
Nonetheless, while I agree with your pushback, I do wonder how much utility there is in the “dogma” approach. There’s a lot of “facts” being thrown around in education, from what I’ve seen, that are often forgotten or become vague memories. How much better would it be to focus on skills and practice and concepts? Especially in the digital age where a fact is easily discoverable, provided one has the appropriate research skills.
Who do you think makes it appear we have it all figured out? That is not my impression at all. All the scientists I know are extremely aware of the limitations of their field.
It is easy for children to come up with questions for biologists that none can answer, and that none has even tried to answer.
Biologists are almost unique among scientists in being happy to say how little they still know about their subject. Up until last year nobody had thought to see whether anything eats viruses! Turns out some do.
To be more precise, viruses are just made up of proteins and DNA / RNA. Your normal digestion that can handle proteins and DNA/RNA from animals, plants etc doesn't have any more problem breaking down virus proteins into amino acids and absorbing them.
I think the OP was talking about the bacteria that derive non-negligible sustenance from viruses.
>Moreover, our foraging trials demonstrated robust growth in the Halteria population with only chloroviruses as food (rint = 0.66 ± 0.26 [SD], black lines, Fig. 1A), with minimal to no growth in the controls (with chloroviruses filtered out; rint = 0.22 ± 0.12 [SD], blue lines, Fig. 1C). The abundance of the larger Paramecium did not increase in treatment or control trials (Fig. 1D), indicating that not all ciliates can grow on chloroviruses in these conditions, even when they consume them.
How could you possible find a citation for that? It’s not even pretending to be a scientific or totally objective claim. Asking for a citation for this type of statement is no way to have a discussion. Do you not see why?
Eh, 'Citation needed.' was my admittedly somewhat snarky way of calling bullshit.
Most any scientist will happily babble all about the stuff they don't know yet in their discipline, because that's exactly where the excitement lies for them.
> Much of Wikipedia is "curated" by retired professors carefully scrubbing mention of anything new that makes their graduate thesis look ill-conceived.
What makes you think so? What evidence do you have?
Magnetohydrodynamics is, specifically, the "easy part" carved out of plasma fluid dynamics. It is inadequate to almost all applications, with only rare, precious exceptions, mostly manufactured. Devices that rely on plasma fluid dynamics to work are carefully designed to keep the plasma in the domain where MHD can be used to model them.
Astrophysicists, as a rule, hate to be obliged to consider phenomena that involve plasma fluid dynamics, even what can be shoehorned into MHD. Such phenomena are thus orphaned, and you won't find anybody talking about them.
The exception is solar physics, where nothing can be done at all without fully general plasma fluid dynamics. Solar physicists have the largest gonads in science, on par with rocket propellant chemists.
I think most consider it "somebody else's problem". I know some don't like to think there is anything to it beyond MHD, so they call anything involving plasma "MHD".
Are there other phenomena they see but don't like to talk about? Maybe?
It has several commonly unphysical assumptions, including infinite conductance, "freezing" the magnetic field in a chosen frame, and assumptions about time and length scales.
"Effects which are essentially kinetic and not captured by fluid models include double layers, Landau damping, a wide range of instabilities, chemical separation in space plasmas and electron runaway."
That electrons are 1836 times less massive than the lightest positive charge carrier is neglected. Accelerated, they strike positive and neutral particles and knock loose more electrons.
> The triboelectric effect is very unpredictable, and only broad generalizations can be made.
> The mechanisms of triboelectrification (or contact-electrification) have been debated for many years, with possible mechanisms including electron transfer, ion transfer or the material's species transfer.
> Recent studies in 2018 using Kelvin probe microscopy and triboelectric nanogenerators revealed that electron transfer is the dominant mechanism for triboelectrification between solid and solid.
> For a general case, since triboelectrification occurs for any material, a generic model has been proposed by Wang, in which the electron transfer is caused by a strong electron cloud overlap between two atoms for the lowered interatomic potential barrier by shortening the bonding length.
So, still very much misunderstood. There is an experiment showing the dominant mechanism (so still only explaining a part!) between solid-solid and a generic model proposed that can be used to explain other interactions (solid-liquid, liquid-liquid, etc).
Unless there's a tested model with predictable results, I'd say we're not really understanding it properly.
> So, still very much misunderstood. There is an experiment showing the dominant mechanism (so still only explaining a part!) between solid-solid and a generic model proposed that can be used to explain other interactions (solid-liquid, liquid-liquid, etc).
This seems like a very large part, no?
I mean, we know it works, we get the majority of it, and it doesn’t seem super necessary to spend a lot of dollars and brain power to satisfy an internet debate on a theory of rubbing a balloon on one’s head.
I get your point. However, this is worked on by researchers who get paid to work on unsolved problems. This is one of them. It's a surprising one, since it looks like such a simple and obvious effect governed by physics we've (seemingly) understood for centuries. Gauss's Laws are from 1773 and much of the work on static electricity is from that era.
So, it's not just an internet debate. Knowing how things work _exactly_ is what scientists do. Getting the majority is not good enough.
And yes, that will often surpass the scale of "Is what we're doing useful?". However, won't know until we find out. Most likely understanding this effect will not bring any revolutionary insight but we should understand it nonetheless. Maybe our understanding will help someone else solve a problem, that solves another problem, that solved another problem, that gives someone a brilliant idea.
Maybe there are researchers who want to study the discrepancies of static electricity but if they don’t get funding, then they won’t be paid and have to take other priorities.
Seeming to demand these problems are resolved is a road to cynicism, in my opinion.
Clearly you've never recalibrated the thermal interferometery scanner so you can reverse the polarity of the neutron flow in the isoneutronic pulse wave carrier.
We do not call it witchcraft, because that is the end of the discussion and the answer. We call it unknown because it is knowable and is the beginning of the experiments.
>We do not call it witchcraft, because that is the end of the discussion and the answer.
Also, we'd have to eliminate the practitioners for clearly being witches. We've had that period and history, but it seems some modern day people are content to bring that very time period back.
"Friction-driven static electrification is familiar and fundamental in daily life, industry, and technology, but its basics have long been unknown and have continually perplexed scientists from ancient Greece to the high-tech era. [...] To date, no single theory can satisfactorily explain this mysterious but fundamental phenomenon." --Eui-Cheol Shin et. al. (2022)
My understanding is that the standard model likely does predict static electricity, but since it's a phenomenon bigger than a few molecules, we have no way to actually run the simulation. The physics is willing but the computers are weak.
My favorite poorly understood phenomenon in basic physics is the Mpemba effect, where hot water can freeze faster than cold water under certain circumstances. It's just phase changes of water in a simple experiment you can do at home, and I think there's still no widely accepted explanation.
> the actual occurrence of the Mpemba effect is a matter of controversy
> In 2016, Burridge and Linden defined the criterion as the time to reach 0 °C (32 °F; 273 K), carried out experiments, and reviewed published work to date. They noted that the large difference originally claimed had not been replicated, and that studies showing a small effect could be influenced by variations in the positioning of thermometers: "We conclude, somewhat sadly, that there is no evidence to support meaningful observations of the Mpemba effect."
> In controlled experiments the effect can entirely be explained by undercooling [water may cool below the freezing point without actually solidifying] and the time of freezing was determined by what container was used.
That's because nobody's replicated that effect in a real lab. People who claimed to observe effect didn't even bother to bypass the freezer thermostat and force the compressor to stay on, nor did they measure power consumption. It's just shoddy science.
> there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to a wall
You mean dielectric moments and static electricity? Electromagnetism is the one thing we know the most about. It's that spooky gravity junk that makes us scratch our heads. It never seems to behave quite right and doesn't mesh with all the other forces.
> You mean dielectric moments and static electricity?
You're confusing what with why. My understanding is that everyone knows it has something to do with electrons collecting on the balloon; but nobody quite knows why rubbing rubber against hair causes the electrons to do that.
Often the gap between what and why is enormous. Humanity began curing meats to protect against microorganisms around 3000BC. The effect of what was going on was immediately observable, but it wasn't until 4500 years or so later that we discovered the why of microorganisms.
I think I got confused because I was thinking about why it stuck to the wall, rather than why it accumulated charge. I know why electrically charged objects stick to things. The why of how they got like that is a bit different as you mentioned. Triboelectric effect is spooky, but there are some theories. It's one of those non-linear messy quantum things that's a pain in the neck to solve.
> That is exactly equivalent to "dunno, maybe something".
Yup! It's like understanding the why of weather and people. They are messy and have so many factors you can't account for. It's like saying, why are the clouds shaped like that. You can why your way down, but it's turtles all the way!
When it comes to non-linear junk, the why becomes mixed up because the causes are so numerous. There are so many tiny interactions you can't really say there is one individual cause. Often times you have phenomena that occur at specific energy levels that aren't really caused by any one thing. Even something as simple as a double pendulum is unpredictable.
One thing that is kind of mind blowing is strange attractors. Systems that are so random you cannot predict them even a few moments later can exhibit seemingly ordered patterns. They seem to have a cause, but they are literally just statistical mechanics. A slightly more likely outcome out of un-countable numbers of other outcomes.
It is entirely possible that global warming could tip us into the next ice age, though probably not in our lifetimes.
First you would need a world-wide cloud layer reflecting insolation back without conversion to IR. As the temperature drops, ice forms. When the clouds dissipate, the ice takes over reflecting sunlight out.
Or it could return us back to the hothouse earth of the cretaceous era. Or it could turn our entire planet into a second Venus with a runaway effect from all the methane. Or it could do almost nothing at all. There is just no way to know because it's never really happened before. We are playing with fire for sure.
If we compare ΛCDM to most other scientific theories it doesn't look so bad in terms of discrepancies. Certainly there are many unexplained effects in solid state physics, there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to a wall and that's an experiment you probably did as a child.