The “Worst Prediction” Was Never Made: The True Story of the Cosmological Constant
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- Опубликовано: 15 апр 2024
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If you google the “worst prediction ever”, you will get hundreds of results that tell you it was the prediction of the cosmological constant that was infamously 120 orders of magnitude wrong. But there has never been any such prediction. Just where does this story come from and what is really the worst prediction ever?
I warmly recommend this paper about how much one can actually calculate of the cosmological constant: arxiv.org/abs/1205.3365
Sorry about the typo at 2:46
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This is fantastic, a German physisist ranting and being extremely entertaining and humorous. Love this channel.
Definitely entertaining. But also saying a few incorrect things. Still much better than "The worst prediction in physics" by Fermilab, also here on RUclips. The guy claims that general relativity makes a prediction on the cosmological constant. No. That constant is a free parameter in GR, as Sabine Hossenfelder says. It cannot be predicted by GR.
"... except for one blogpost, which says otherwise, and that, hmmm, comes from my own blog" - Love it! kudos.
Much preferable to ... certain individuals ... claiming that "science shows X" and, for support, referencing their own earlier publication ... which asserts this without giving an argument. And yes, I recently heard of such a case - I think it was a creationist.
Yes, I agree. The flat earth model would make a nice birthday cake design also.
we call them Maps
Earth is locally flat... if we ignore all the roughness.
duh...
I was recently attacked by flat earthers! They say the Bible tells them so. I ask where? Firmament can be explained by just calling it atmosphere, can't it? They believe in an omnipotent God, then take away all his powers. Insane. They give the devil equal power. Lol
@@andrewruiz7894 Everyday Christians roll their eyes at them too. The flatheads overlap with the fringe literatlists who believe in shallow, literal interpretations of scripture but miss the higher allegories of the text.
science lady ranting about funny math is my new favourite youtube genre
And mine would be people that don't comprehend that the math represents the closest thing possible to an absolute reality.
@@Harlem55 Okay Neo.
Welcome!
Science lady with cool accent, that is! Which is basically the same thing.
@@Harlem55 What part of reality does the square root of -1 represent?
Stories like this are one of the reasons I watch this channel. No other scientific communicator would do this. Thank you very much Ms. Hossenfelder.
And even in physics lectures at a physics degree course they tell you this. Unbelievable how broken physics research is
Thunderf00t does, but yeah, Sabine's the only one who does it daily.
@@gabor6259 - Yes... but I can't stand that guy. 🙂 Though, perhaps I should've mentioned him. I don't think of him as a science communicator though so much as a professional gadfly.
@@Omnifarious0 personally, I think of him as a smug git
I love your mind. You bring humour to serious critical thinking...
Thats serious critical humour !!!
I once made a error of a factor of 10^30 - when inverting an equation I multiplied by the exponential when I should have divided by the logarithm.
I hate when that happens!
Well, that's an easy mistake to make.
Or is that a mistake to make easy?!?
If you want to remodel your house, a flat earth theory is actually a very good approximation.
Now I wonder how large a house need to be (in each directions) where flat earth approximation can not be used anymore and we’d need to account for the shape of the earth, assuming an uniformly spherical earth, otherwise the answer would be a function of the coordinates.
@@smlckzIf my calculations are correct, a house the size of 80 m * 80 m * 80 m is 1 mm wider on the top than on the bottom.
"Flat earth models might make nice tablecloths." Oh, I laughed out loud at that one!
Informative, Consistent, and a little light hearted... great work Sabine....
… I’ve been reading about this on & off for quite some time. Never seemed to know how to think of these discrepancies that you talk about. Thank you so much for clearing this up in my mind.
vacuum energy is singular in QFT. If you quantize spacetime down to the Planck units, you get the 10^123 result.
To some degree, it's actually the exact same problem as the ultraviolet catastrophe in a different setting.
@@JonBrase Huh... when you quantize, you go from infinity down to E123... the experimental result is something like 10^-27 g/cm^3... :D So still waaaaaaay off :D
there have been calculations including fluctuations of vacuum fields, which reduces the value drastically. The 10^120 are just a mean field approximation
Or you just normal-order your quantum fields from the start and the issue never appears (maybe with subtle caveats down the line past tree-level order).
@@NuclearCraftMod Isn't this nonrenormalizable?
I thought I remembered something about Einstein adding a constant to make a "steady state" universe and avoid a big bang. The impression I had was that adding a constant to make the equation turn out the way he wanted was his "greatest mistake."
He thought it was, but he was wrong. We may well need it. Or not. We don't know yet. But it was less obviously wrong than he thought it was.
@@jameshart2622yes we know, the cosmological constant IS NEEDED. We may discuss what is the actual value for our universe, but it is definitely not equal to zero.
As I understand it (and I could be wrong, so we should probably both go and check the facts after I've waffled), it wasn't that he was consciously avoiding a big bang or anything like that. Simply by the mathematical rules of how you solve an integral, there's always going to be an unknown constant, which literally could have *any* value and the result would still fit the equation you set out to solve. That's because there simply isn't enough information in the differential equation(s) you're starting from to let you pin down what the constant would be; You have to get that information from somewhere else. (And it gets worse with a double- or triple-integration: Every extra stage of integration generates another unknown constant.)
At first, Einstein included the constant, following proper form, although he assumed it had no physical meaning, or any value other than zero. When people looking at his theory started discussing what this unknown constant *could* mean, he thought they were just getting distracted by a non-issue; a mere artefact of mathematical technique... He wished he'd never mentioned it, and took it out of later published versions of his equation(s)/theory.
However, time eventually showed that the constant *does* have physical meaning, and definitely isn't zero. So I would say Einstein's greatest mistake was the opposite of what he thought it was. =:o}
@@therealpbristowYour considerations are quite consistent, but the historical plot is more like follows:
• 1915: Einstein GR w/out Lambda (or w/ Lambda = zero)
• 1927: Lemaître "Big Bang" theory due to Einstein GR, Einstein disagrees and wrongly introduces Lambda < 0 for static or steady state universe
• 1929: Hubble Expansion due to observation confirms "BBT"
• 1933: Einstein, Lemaître & Hubble agree on expanding universe (consistent with Lambda = 0)
• 1998: accelerated expansion discovered, leading to Lambda > 0 (re-introduced for the opposite reason than originally) corresponding to "dark energy", then combined with preceding cold dark matter (CDM) cosmology to form Lambda-CDM
🤓
Which is where we are now, and which is most probably "wrong again" (and again and again)… 😆
This is the kind of Sabine videos that I love.
You're the first person I've heard that addressed this. Thank u.
Fascinating! Thanks, Sabine! 😃
Stay safe there with your family! 🖖😊
Sabine and Anton publish such clever and polished science videos, prolifically, without tje giant PBS production apparatus. Sabine and Anton, the true mysteries of contemporary physics!
I would love either @whatdamath or @SabineHossenfelder to do a video comparing Noble Gasses _> Absolute Zero & Speed of Sound _> Infinite energy as density approaches infinity (Yes, irrelevant comment, I would sorely like to see it addressed).
Also, RE: GR/QFT - does the vacuum have a resonance state? To my knowledge, "it" seems to be one of the very, very few "things" in the universe to which resonance appears not to apply... unless I'm wrong.
@@GeekusKhaniCAs idk if you're correct in your understanding, but now I want to see that video made, too
Mother of all miracles! Sabine changed her shirt!
What happened to her? A couple years ago she wore really nice clothes, she was the best dressing physicist on RUclips but now she wears the same 2 shirts. 🤔
Excellent. I love using "numerological" as pejorative for the naturalness arguments. One of those things I wish I had thought of.
It's as if theoretical physicists are so insanely competitive they need to be the best at everything, including being wrong.
Publish now, be wrong later. Getting cited for being wrong increases h-index just as well.
Danke, Sabine, for keeping us grounded.
The ultraviolet catastrophe and the 10^120 prediction have actually the same cause: An integral about energy/frequency/wave length that does not converge. To get some value out of it anyway, you have to replace it by a formula that does converge (Plank's formula) or to choose some limit (Plank length).
The reason integrating the Rayleigh Jeans equation gave infinite energy is that it assumed that the black body spectrum was a continuous function and therefore integratable. But since light comes in quanta it is not continuous and leads to a false result.
@@MagruderSpootsA continuous function with countable discontinuities is still integrable. The issue is the divergence at shorter wavelengths. Taking into account quantisation changes the functional character in the limit lambda->0 (from above).
The black body radiation spectrum should not be confused with the atomic or nuclear emission spectrum.
Strength of conviction Sabine - WELL DONE
Hello Miss Leading, I'm Dad
Nice to meet you, Miss Lee Ding.
Hello Miss Leading, I am Miss Information.
She sleads us awry.
@@drbuckley1 Hello Miss Information, I am Miss Trust
I am miss understanding:)
Thank you for this info.
“Might make a great table cloth.”😂😂😂😂
I find the the constant stream of memes in the corners distracting from the important information sabine is sharing. i think her humour is just the right touch for the material.
One of my textbooks accidentally omitted the minus sign on the exponent of Planck's Constant. I pointed out in class that this was an error of 68 orders of magnitude. The class and professor seemed nonplussed.
This is absolutely one of my favorite channels.
Best video of you.
UV cut off is physical procee in experimental optics which have widely used in theoretical physics in various event but it is now very useful for spectacles. A black body besides noses .
well considering the observable universe is like 250 times smaller than the actual size i think it is safe to say that what we observe as the expansion of this sector could easily be a current within the sea of the heavens so to speak.
Best comment I’ve read so far!
Thank you for the video.
Thank you for clarifying things that no professor ever clarified to me
Thank you so much!!!
You go, Sabina. Busting out is a great 👍 gift to us all. Peace ✌️ 😎.
Brillant episode !
That "it isn't natural" argument is what I hear when I try to tell people that the substance of matter and energy, what it truly is, is math somehow playing itself out. Not in the Max Tegmark sense, but empirically, we can say that if any non-mathematical properties of particles/energy exist, they have no effect on anything we can detect, and may as well not be posited to exist. What's the name of the related fallacy again? The invisible pink unicorn / purple dragon argument.
That also means that the fundamental questions change somewhat...rather than the big deep being "why does something exist instead of nothing," it becomes "how is it that math plays itself out" or "in what fashion can mathematical values even exist".
People *REALLY* don't like that though. They fight tooth and nail, doing things like citing consciousness while ignoring the fact that it would be (and likely is anyway) emergent, or "look around you there's no way, never," etc. I mean even Stephen Hawking pointed out the mathematical nature of things by asking that famous question of his, "what is it that breathes fire into the equations," but the idea seems so unnatural to some people that they basically go "no, no, no, it CAN'T be true!!!"
That "it is/isn't natural" argument can be potent, I mean *extremely* potent, like "this idea breaks my reality and I can't deal with that" potent. Very intelligent people can be completely oblivious when they're doing it too.
"...flat earth models might make good tablecloths." 😂🤣😂🤣
I prefer a spherical table! Now I just have to figure out how to fix that prediction so and make my table's gravity 10^120x stronger so stuff will stop falling off.
I don't remember what it was exactly, but a formula that flat earthers use as "explanation" for the "apparent" curvature of the Earth is actually really easily converted into a close approximation of the actual curvature of the Earth for the first several hundred or so kilometers, while being much easier to use than doing the actual math on a spherical object.
@@Leyrann Flerfers actually have some pretty good math to explain many of their concepts.
The problem is that their math isn't consistent across concepts. They can describe the day and night cycle, or they can explain the seasonal cycle.
But they can't describe both at the same time. Each concept require moving the sun around in the sky, and the require motions are incompatible with each other.
Essentially they're trying to explain both the rotation of the Earth around its own axis (day/night) as well as the Earth around the sun (seasonal) with a single degree of rotational freedom (the sun rotating around above the "Earth").
Simple dimensional analysis tells us why that will never work. They would have to introduce some secondary form of rotation to explain both. The obvious answer would be to toss some kind of rotational phase on the sun (eg: dims and brightens in a cycle), but then they'd just have to explain what causes that. And in this case they don't even have an appeal to biblical literalism to make - God didn't say "let there be light! And then dark again, and light again, rinse and repeat!" or anything along those lines that they could try to hack into a "it's just God's will!" argument.
(Of course they also fail to explain things like eclipses, but given that they can't even get the basic stuff right I'm not going to worry too much about their handling of the rarer events.)
How flatearth explain seasons? And how come Australia have opposite season to us!?!
@@MichaelWinter-ss6lx I don't remember the details because I don't care that much, but basically the sun just slowly circles around the Earth, so the further half is "winter" while the closer half is "summer". There's more complexity to it to try and explain why the sun is physically lower in the sky in winter and higher in summer (it also slowly moves north and south in a sinusoidal pattern over the course of the year so that its always "near" the appropriate tropic during summer in each hemisphere.
The big problem though is that the sun can't simultaneously be going around the Earth in 24 hour cycles (day/night) and in 365 day cycles (seasons) at the same time. They can make the math work (roughly) for one or the other, but not both at the same time. They keep trying to be sure, but it never _quite_ works. They're simply missing a necessary degree of freedom in their attempted equations.
Short. Sweet. Fun. And with a nice side swipe. I like it! 😁
The 'infinitely wrong' thing reminds me of convergence of power series in the complex plain. For example the zeros of the Riemann Zeta function are very important in pure mathematics. The definition of the Riemann Zeta function* as a sum Σn^-s doesn't converge anywhere where there are zeros. Oddly enough one can analytically extend, meaning we can get a function which is defined everywhere (except 1), and agrees with the sum definition. But in the critical strip, for example, the Σn^-s definition is 'infinitely wrong'.
Good point on the ultraviolet catastrophe being the worst ever. There's also the one where electrons must fall into the nucleus of an atom.
At 4:34
I was in need that joke and the laugh it gifted me. Thanks!
What a delightful and interesting video! Thanks for explaining these 2 "predictions". However, I have to philosophically disagree with the statement at 0:48 that "The cosmological constant determines the expansion of the universe" and say, instead, that it "describes" the observed expansion of the universe. Lambda was, as I understand it, added by Einstein to prevent his equations from describing and expanding or contracting universe. Then it was thrown out and disowned by Albert. But now it is back in favor to describe the increasing rate of expansion discovered in 1998. Like the proverbial magician's rabbit, it is pulled out of the cosmological "hat" as needed to explain something we don't fully understand.
When I hear physicists babbling about the Planck units being important, I like to point out that one Planck mass of water is a droplet big enough for some tardigrades to have a party in, which the Planck momentum is roughly that of an adult cat running vigorously - possibly in pursuit of whoever stuck it in that box with the vial of poison gas and an apparatus to break it if some random thing happened.
0:38 The problem is not in the worst or less worst predictions, but in the methodical sacrifice:
in the presence of Λ(0) in Einstein's equations Newtonian mechanics is no longer a special case of GR.
P.S. The relativistic equations of the gravitational field can be reached intuitively, based on the Poisson equation: Δφ=4πGρ. Now it is required that in the case of a weak field in GR, the Poisson equation is obtained, and this took place {by the way, a generally recognized achievement and “...a great success of GR” (Pauli, RT)}. But only when there are still unknown constants in the desired equations: a=-1/2 (which can be determined using the equivalence principle) and, attention: Λ(0)=0.
Initially, in 1915, Einstein wrote the equations exactly in the form: R(ik) - (1/2)Rg(ik)=(8πG/c4)T(ik), i, k=0,1,2,3. , however, for philosophical reasons, in 1917 he added the unknown constant Λ(0)* to his equations as a "cosmological constant".
Modern speculations** with an unknown constant based on the equation: T(ik)^v=-(c^4/8πG)Λ(0)g(ik), where T(ik)^v is interpreted as the energy-momentum tensor for vacuum. Further worse: it becomes necessary every time to take into account the limitations imposed by the observational data on the value Λ(0).
----------------
*) - After Friedmann's solution (1922) Einstein discarded it.
**) - "A good joke should not be repeated." (Einstein).
Something that looks like a cosmological constant can still appear in solutions to the Poisson equation. For example, in the special case of a constant matter density, the differential equation is 1/r^2 d/dr (r^2 dφ/dr) = 4πGρ, which has the solution φ = A/r + B + 2πGρ/3 r^2. The first term is the standard gravitational potential energy, the second term is a constant, and the third term yields an outwards force proportional to the distance from your origin of coordinates.
@@NuclearCraftMod
In other words.
1. It follows from the variation of the full action: R(ik)-Rg(ik)/2=-(1/2ac)T(ik). Comparing with Einstein's equations of 1915, we find a=-c^3/16πG. Strictly speaking, in order to determine the constant a, it was necessary to make a transition to the Poisson equation. Thus, a rigorous derivation of Einstein's equations can be given.
2. And from the variational principle, one can also obtain a cosmological term by replacing the scalar R with R -2Λ(0), where Λ(0) is the cosmological constant. But in the Lagrangian expression Λ(g)=-2Λ(0)+R, in fact, only the zero and the first term of the decomposition of this function are taken into account. And taking into account nonlinear combinations from the curvature tensor and its convolution has the disadvantage that leads to field equations containing derivatives of g(ik) above the second order. Moreover, the need to involve nonlinear terms of Λ(g) arises when taking into account vacuum quantum effects.
3. The transition to the non-relativistic limit allows us to determine a constant factor for the integral of the gravitational field according to: R(0)^0=(4πG/c^2)p; Δφ=-pc^3/4a=4πGр, where a=-c^3/16πG.
In other angle.
From Kepler's third law follows: M/t=v^3/G, where M/t=I(G)=[gram•sec^-1] is the gravitational current.
By the way, in SR: I(G)=inv; this follows from the Lorentz transformations: m=m(0)/√(1-v^2/c^2) and t=t(0)/√(1-v^2/c^2). Hence, obviously, we have I(G)=m/t=m(0)/t(0)=inv.
In the case of the Universe (see Appendix): I(G)=M(universe)H=m(pl)w(pl)/8π=c^3/8πG=-2a (~ the "dark" constant).
That is: Δφ=-pc^3/4a=рс^3/2M(universe)H^2. The critical density value determining the nature of the model is: p=(3/8π)H^2/G. And
Δφ=4π[с^3/Gm(pl)w(pl)]H^2=4πH^2;
which is evidence of a phenomenon: spontaneous Lorentz transformations. Thus;
Δφ(0)/Δφ=w(pl)^2/H^2~6,4*10^121, where Δφ(0)=4πw(pl)^2; the best prediction.
Appendix
1.Expansion is a special kind of motion, and it seems that the Universe is a non-inertial frame of reference that performs variably accelerated motion along a phase trajectory, and thereby creates a phase space.
2.Real gravitational fields are variable in space and time, and we can now talk about the fact that it is possible to generate a gravitational field in a non-inertial frame of reference (|a*|=g).That is, finally achieve global (instead of local in GR) compliance with the strong equivalence principle.
3.{According to general estimates, this acceleration is: |a*|=πcH:
the equations of the gravitational field can be arrived at based on the Poisson equation Δφ=4πGp, and for a weakly curved metric, the time component of the energy-momentum tensor: T(00)~=pc^2. Therefore, the Poisson equation can be written as: ∆g(00)=8πGT(00)/c^4, where g(00) is the time component of the metric tensor. This equation is true only in the non-relativistic case, but it is applicable to the case of a homogeneous and isotropic Universe, when Einstein's equations have only solutions with a time-varying space-time metric. Then the energy density of the gravitational field: g^2/8πG=T(00)=pc^2, where the critical density value determining the nature of the model is: p=(3/8π)H^2/G. Hence it follows: g~πcH. And according to the strong equivalence principle: g=|a*|=πcH.}
4.However, а*=-2πcа/M (universe), what is F=M(universe)а*=-2πса=-с^4/8G=-(⅛)F(pl).}
5.Then the energy density of the relic radiation, that is, the evolving primary gravitational-inertial field (= space-time): J= g^2/8πG=(ħ/8πc^3)w(relic)^4~1600 quanta/cm^3, which is in order of magnitude consistent with the observational-measured data (about 500 quanta/cm^3).*
P.S. You can also use the Unruh formula, but with the addition of the coefficient q, which determines the number of phase transitions of the evolving system for the case of variable acceleration: q=√n'=λrelic /√8λpl , , where n'=L/8πr(pl) is the number of semi-orbits; L=c/H, is the length of the phase trajectory.**
Thus, T*(relic)=[q]ħa*/2πkc (=0.4K), which is in order of magnitude consistent with the real: T(relic)/T*(relic)=2,7/0,4=6,7.
However, there is no need to have a factor of 1/2π in the Unruh formula in this case.
------------
*) - w(relic)^2=πw(pl)H,
|a*|=r(pl)w(relic)^2 =g=πcH,
intra-metagalactic gravitational potential:
|ф0|=(c^2)/2(√8n')=πGmpl/λ(relic)=[Gm(pl)/2c]w(relic), where the constant Gm(pl)/2c is a quantum of the inertial flow Ф(i) = (½)S(pl)w(pl) = h/4πm(pl) (magnetic flux is quantized: = h/2e, Josephson’s const; and the mechanical and magnetic moments are proportional).Thus, the phenomenon can be interpreted as gravity/inertial induction.
m(pl)w(pl)=8πM(Universe)H;
{
w(relic)^2=πw(pl)H.
From Kepler's third law follows: M/t=v^3/G, where M/t=I(G)=[gram•sec^-1] is the gravitational current. In the case of the Universe, I(G)=M(universe)H=c^3/8πG (~ the "dark" constant).
**) - n' =4,28*10^61;
w(pl)=(√8n')w(relic)=8πn'H; where H=c/L.
H=1,72*10^-20(sec^-1).
By the way, it turns out that the universe is 1.6 trillion years old!
The area of the "crystal sphere": S(universe)~n' λ(relic)^2~n'S(relic).
r=2.7*10^29cm, L=2πr.
Δφ=4πGр=[4/πw(pl)^2]w(relic)^4.
Addition
In an arbitrary non-inertial reference frame, the equation of the total mechanical energy of a particle system is: ∆E=A(internal)+A(external)+A*, where A (internal) is the work of internal dissipative forces, А(external) is the work of external non-conservative forces, А* is the work of inertia forces. In order to preserve the mechanical energy of the system in a non-inertial frame of reference, it is necessary that ∆E =0, however, in an arbitrary non-inertial frame of reference, it is impossible to create a condition for fulfilling this requirement; that is, ∆E does not =0 in any way (by the way, in system C, the condition for fulfilling the laws of conservation of momentum and angular momentum does not depend on whether this system is an inertial or non-inertial frame of reference).
it would scale as power 4 if it were photons... but not if it were some exotic form of energy... The unit is GeV^4 ofc, but most of it could be just constants... I skimmed through the paper linked in description but didn't find the exact scaling used. I did find the log m^2 part though...
nice top! kind of futuristic like the uniforms in "Space 1999"
This is a very uplifting message of hope for all those failed theories out there. You may be terrible at your job, but you can still be useful. Thanks for the positivity!
Other physicists: "We build CERN and find dark matter, supersymmetry, create a tiny black hole and magnetic monopoles. And prove string theory right."
Sabine: "No, you won´t!"
Spoiler: They didn´t.
Other phycisists: "It´s all Sabines fault. We should have her sacked!"
That´s in short, how things go in "science" these days. 🤪
@Sabine : Great fan of Yours! Thank you for your work.
Most physicists were hoping to find evidence of supersymmetry but the rest, not really.
Off-topic: Hey Sabine! Please make a video about "On Hawking radiation and the Casimir effect" by Darragh Rooney. I haven't read it fully, but it seems quite interesting!
Sabine is kept awake at night by concepts I can’t even comprehend 😂
Sabine are you doing Q&A’s?
This is one of my many pet peeves in physics communication
I'm so glad at least I'm not completely crazy.
Can you talk about the recent maping of the universe and what it does say about the expansion of the universe
I got a Question that is boggelin my mind for a long time:
The universe is expanding, What happens to the vacume energy density in that expanded space ?
Does it get diluted / less vacume energy per unit of space ?
Is it save to say that that space on the tiniest scales is uncurling and hence spacetime tension/curvature in the universe as a whole is Relaxing the tension in these quantum bubbles ?
Thoughts ?
I've heard science communicators say, as if it was a settled matter, that there is a constant amount of dark energy per volume of space. So if the volume of space doubles then there is twice as much dark energy in the universe, making the universe expand even faster. But about a week ago I heard Fraser Cain (if memory is correct) talk about a group that was trying to measure precisely how much expansion was accelerating.
Thank you, it's great that someone is naming things by their real names and doesn't fall into science "fashionable" stories.
Isnt there an integral over some oscillation modes in QED that actually gives you the same combination of fundamental constants as the planck mass to the fourth power? That doesnt seem as pure numerology or naturalness.
I don’t know how Newton’s constant could appear in a QED formula unless arbitrary thrown in as part of a Planck length/energy/etc.
Quod erat demonstrandom.
"Which was to be demonstrated"
QED
Who is Miss Leading? I'd like to meet her. Perhaps she's related to Miss Pelling. 🥰
I like your view of the usefulness of the flat earth model, that it makes a good table top - though I always thought it gave giant cozmic turtles a reason to exist - but table tops are good too.
Thank you for the video.
I think we should add, that there is no reason to think, that the quantum vacuum gives rise to the cosmological constant.
The geometries of the GR and QM are very different, so there is no reason to think, that the vacuums in those theories are the same.
According to QM the vacuum has energy, and according to GR energy curves space time. This is where they overlap and measured energy (GR) of the vacuum from the curved space time should be the same as the predicted energy of QM. They are not. The geometries are not important. What is, is the energy values. A difference of 10 ^ 13, from the video, is still a very large error.
I heard that Einstein had put the constant into his equation because he felt the universe was static and unchanging and later when Edwin Hubble showed that it was expanding , he said it was his biggest blunder. It's a good thing they haven't quantized gravity because they would have turned everyone into black holes by now.
The motto must be never believe a theorist until you've actually measured whatever it is they've predicted. And even then check you haven't done the measurement wrong (I've done that before!).
If theory and experiment agree, they are most likely both wrong, my PhD supervisor said.
If you ever decide to market that tablecloth Sabine, I'd buy it from you!
Flat earth model is perfect for calculating trajectories of a soccerball, lots of wrong models are useful (thatsway they exist), which is I think is awesome
I hope one day Sabine will talk about one thing that she can agree with on the record, as the result of what she learned in physics so far.
Thanks for this video, I was wondering the same thing - how come scientists don't seem to care about a 10^120 discrepancy
Well. Plank time says that at the origin of everything there is a moment when the laws of physics do not apply. Which means you can put anything, anywhere, for free. Its like setting up a chess board before a game, moving pieces doesn't cost any time or move points. Working backwards this places the observable phenomenon as cosmological constants merely pieces on a board dialed to an exact starting point with only so many possible outcomes by the end of the game
Fermi did comment that the universe is made of iron (mostly). This was the actual issue that he addressed not that make up constant which was created to explain it.
Small problem I've noticed on many of these videos - they won't keep playing with screen off which is one of the paid perks of the RUclips premium subscription.
I don't know if it's because they are "Members only" videos (I'm not a member of many channels so don't have a lot of cross comparisons there to draw from), or maybe they are tagged/submitted as a "RUclips shorts" format?
I know the shorts format videos don't play with screen off, so maybe that's it? That typically isn't an issue, as those are usually like 20-30 seconds and something I'd actively watch. But many of these types of videos from Sabine I'm noticing this on are 5-8 minutes or so, and not a graphically driven video, so just the type and just long enough it would be one I'd start while driving around town and then turn off my phone and listen via car Bluetooth. Do it all the time. But these I have to remember to leave my phone display open.
Minor annoyance but thought I'd mention in case no one on Sabine's team realized this happens and it was an easy fix.
Otherwise.... love everything about this channel! One of I think just two channels/creators I'm a paid member for in any format.
It only works if you have a Premium subscription. However, this is why we have a an audio-only podcast (see link in info)
No it´s not because of "members only", that just means, that you have earlier access to the video as member, before it gets published. You can leave a comment in that "time window" and she often reacts on that, what is really nice. But I don´t think there´s an influence on how the video runs for the creators.
I've used the non-premium RUclips app (on an Android smartphone) for years, and my experience is that NO videos play with the screen off (or with some other app in foreground).
Of course, that taught me to leave the screen on and leave the RUclips app in foreground. So it's possible there are exceptional videos I don't discover.
I am a RUclips premium subscriber exactly for that purpose. I listen to a lot of content while driving or before going to sleep. Some stuff like this video I could collect as podcasts and listen that way but there's some content that I like that's only on RUclips, so a little more convenient to just listen all in one place.
You could always use GrayJay.
thank you thank you thank you, I was complaining about this on the fermilab channel the other day....
this is the same type of "prediction" that years ago told us that there would have been SUSY at LHC
EDIT: and then you say the same thing as soon as I am writing. thank you again
A+ for the Good Burger reference
Perhaps the added cosmological term keeps matter just above the singularity.Even a superdense star would behave almost like a black hole. The strong gravity would cause a significant elongation of wavelengths, and the radiant power and temperature at the surface of the star would be different from what we actually observe.
Are you suggesting that vacuum energy does not have any gravitational effects (ie that it doesn't contribute to T_{mu}{nu} on the right side of EFE)? What reason is there to think that it wouldn't? Does that also mean that you think the energy density between two Casimir plates would really contribute a negative energy to T_{mu}{nu} in EFE (ie a genuine weak energy condition violation, not merely a "relative" negative energy compared to the surrounding vacuum energy)?
Exactly. I made the same point. Obviously the zero point energy prediction is wrong, but it can only be discarded after fixing the theory.
Sabine wouldn’t the other big problem with the standard model be the collapse of the wave function? That’s what Roger Penrose has stated. To me that’s equivalent to Newton’s law of gravity not being able to predict the orbit of Mercury. Or, is that just a free parameter of QM which must me measured? Please elaborate. Thank you.🙏
"wrong, misleading, and wrong again" is a nice citation to use if someone brings this up 😊
I want that table cloth!!!
Heck, I'd like a table top with a flat map of Earth made/engraved in the top!
:)
4:35 Isaac Asimov's "The Relativity of Wrong" comes to mind
What? I always hear that regarding the vacuum energy. That's weird.
btw. Newton was infinitely wrong about the amount of energy needed to accelerate an object to 300.000 km/h as well. Though I don't know how well that comparison holds up
You won me over with (b) Miss Leading. :) Subscribed.
When I saw the title I thought it was going to be about the Ultraviolet catastrophe :D
Ironically, wasn't that what lead to the discovery of quantum physics?
Haha. I thought this 10^120 'error' was similar in nature to the UV Catastrophe. In other words particle physicists calculated the vacuum energy in some clearly wrong way that produced a very high value, when in reality there's some reason the low energy terms have a small limit rather than a very large limit.
It's not easy to borrow from the "plenitude" vacuum if it's 10^120 times less than the expected value. lol. Still, one can always borrow below the Planck time, 5.39 ×10^44 s; and put the Higgs Boson off shell...until you realise that only dual or higher will do.
I WOULD LIKE TO DISS RENORMALISATION...but I realised everything can be turned into a harmonic oscillator when you integrate the Born Rule, Fourier series and transforms, and the Gaussian Normal Distribution. In other words, there are no infinities ( or zero).
01:00
How do you even calculate Λ from the standard model of particles in the first place?
It's what's left once you subtract the surface tension from the handwaivion term.
Yeah, I am looking for the value of this constant as well. Any thoughts? ( Not from QM) actual.
Sooooo excellent! ❤
So funny, Sabine! I laughed!
Matter to matter, light to light
Nah Sabine, Albert Einstein -where: “The conservation law is preserved in that by setting the λ-term, space itself is not empty of energy.” (O'Raifeartaigh, et al., 2014, p. 7.) Mr. Einstein explicitly had the concept of the mitigation supplied by lambda in his equations and even within the overall context of is ideas, it’s present. Whether those concepts are correct, are certainly up for debate😉
They do! The models are continually tweaked as reality intrudes on the predictions.
What chaos related models can't do is predict the exact place and dimensions of outliers... hence unpredicted freak weather.
Unironically, please sell flat earth tablecloths. I would buy one in a heartbeat
@SabineHossenfelder This video made me wonder about one thing: does gravity influence other force carrying fields? I mean, gravity deforms space-time. If electromagnetic field and others existed in that space-time, shouldn’t they be deformed the same way? If not, do they exist in higher dimensions?
Classical electric fields in General Relativity are pretty standard (there are for example solutions for charged black holes). Also quantum field theory in curved spacetime is an existing field of study. And yes, the fields are affected by spacetime curvature (otherwise, light, which is just one form of electromagnetic field, wouldn't bend in gravitational fields).
@@__christopher__ Thanks, that makes sense. I was hoping to get such answer. This leads to the following question: does the energy density of those fields depend on the volume of space they occupy? I mean, if a field gets crammed into a smaller space, it should generate a stronger force, shouldn’t it?
you can get the cosmological constant from the surface term in GR, for instance Smoot has a papers on Entropic Universe on it, Arxiv probably. Can't reply, youtube messes it up for who knows what reason...
George Smoot?
@@PMA65537 Just in case RUclips goes fascist again: Entropic Inflation, Entropic Accelerated Universe by George F. Smoot on Arxiv
@@PMA65537 it really doesn't let me reply... yeah, search for Smoot papers on Entropic somethings... Put a surface term on the Hubble Horizon and redo the Fridman metric with it. You get late time accelerated expansion.
Nice idea for merch. A tablecloth with the flat earh model that can't have sunsets and a tablecloth with the flat earth model that can't have timezones 😂
Looks like cosmological constant that same vacuum energy played with gravitational constant to describe universe balance but accelerating expansion flushed down everything along with spacetime. How dark energy do acceleration only on the edge of visible universe, how GR fit there spacetime? So science sinking in mirage theories
The worst part about the Rayleigh-Jeans Law is that you can get to Planck's Law from some thermodynamics and assumptions that energy is quantized.
@sabinehossenfelder, What's with the red "Hotline" phone? Is that a direct line with Sean Carroll in case Elon's ego tears a hole in spacetime?
Wow, I want to say that was some "OG Sabine!" (not using the expression quite the normal way). What we subscribe for!
My own example of entrenched nonsense would be the term "information theory." There is no such thing. It's just that journalists thought Shannon's Mathematical Theory of Data Communication didn't sound sexy, so they changed its name to "information theory" (and eventually, even he caved to the journalistic pressure'). The trouble is, that misbegotten term now prevents the human species from pursuing anything called its (real) theory of information. It would simply be too confusing (e.g., for po-faced journal editors). Consequently, it will be one of those Superintelligent AIs that creates the first (actual) Information Theory -- maybe a few months from now? -- on our behalf. A tragically missed opportunity on monkey-planet.
Quantum: 10^93g/cm³ vs Outter space: 10^-29g/cm3
Make the proton -that has this quantum density- the diameter of the universe and boom solved
Flat earth models definitely have a ton of uses. I personally very much enjoy them in fantasy worldbuilding since it removes the need to contend with the idea of planets in works that would typically rather use alternate planes or pocket realms as its off-world locations.
I get quite irritable at the constant implication that Raleigh Jeans was in some way incompetent.
It wasn't. It was the necessary step that led to work that gave us Plancks Law.
Why do people assume that scientists go straight to the 'right' answer, a single solution that will stand the test for all time and is useful in all circumstances?
Because they know nothing about the scientific method. A wrong prediction, especially if it's derived from a theory which yields very good results in other cases, far from being useless, is a major hint that something needs to be changed. The ultraviolet catastrophe was a major hint that classical physics, as useful as it is for everyday life, cannot be all there is. Most people know about the photoelectric effect, but Planck's interpolation formula came first and was the first instance of quantized radiation