> Hiragana being far more useful to know starting out, if you had to pick one.
Before visiting Japan, I learned to read in both Hiragana and Katakana, but I didn't really know more than a dozen or so words in Japanese. While visiting Japan, I found Katakana to be a lot more useful, because it's commonly used and often is just English words converted to Japanese letters. I think all my Hiragana reading abilities were completely useless as I couldn't tell what I was reading.
> I think all my Hiragana reading abilities were completely useless as I couldn't tell what I was reading.
This is what many people don't realize when they wish they wouldn't have to learn Kanji or Hanzi. They make a lot of sense for languages with lots of homophones.
This sounds easy in theory, but so far only one language has succeeded in completely getting rid of the Chinese characters: Vietnamese. This transition was imposed by the French colonial administration however, to more easily spread European-style civilization by breaking their connection to their native culture. A Vietnamese-speaker would have to tell whether there are any issues with homophones nowadays.
In Korea, Hanja are still actively used for disambiguation of homophones in complex texts. Public debate was divided for a long time, and even though Hanja are slowly being phased out, it is a slow process. It's hard to tell for sure, but even in North Korea the process seems incomplete.
Kinda but different scale, the CMB era universe was about 1100 times smaller than that now, so still huge.
There may be a neutrino background behind the CMB, where the universe was even smaller, and the gravitational wave background behind that with even more of a size difference.
Would the universe in those other 2 older events have been 2 orders of magnitude smaller still? Have there been any estimates made for the sizes in each "event"?
Are there even more events further back, or is the next one after gravity the big bang?
What a fascinating subject, thank you for expanding my own little universe!
I'm skim-reading on mobile right now, so here's some more information, but I didn't see anything about how much the universe expanded since 1 second after the big bang, which is the relevant number for the neutrino background:
As in a white hole is the big bang? That has a kind of poetic symmetry to it, with black holes (big crunches?) being the end, and white holes being the beginning of our particular universe.
But our universe has black holes in it. Forgive the layman thinking, but does that mean we're just one of an infinite series of "nested" universes?
The energy in our universe is not unlimited, so perhaps each black hole spawns a new universe, and each has less and less energy in it. Think about, WHY is there a certain amount of energy in the universe? Why not more or less. Maybe it's just universes all the way down.
There were no objects before the CMBR. The universe was so hot that atoms couldn't even form. Once it cooled to the point where hydrogen atoms came into existence, the CMBR became possible. I'm talking at the limits of my knowledge, so allow me to refer you to this video by Fermilab that's pretty good.
I think OP's question related to the observable universe vs what is beyond. We see the CMB (and thus our limit of light) only to a point, but that doesn't mean there's nothing beyond that - otherwise we'd be the literal center of the universe (I recall an old minutephysics video[0] on this).
The CMB is everywhere, but it was emitted by the initial formation of neutral hydrogen (from plasma) in the early universe. When people talk about the CMB being far away they're really talking about the last scattering surface, which is that early plasma as seen 13+ billion years later.
CMB is produced by atoms, right? We see darker/lighter regions in CMB, so we should see a transition somewhere. 300M years is very short period of time, unless everything cooled very very uniformly, which is not the case. Sometimes, somewhere there must be a galaxy past CMB.
> 300M years is very short period of time, unless everything cooled very very uniformly, which is not the case
~300M years is the time between the Big Bang singularity and the CMB, but not really relevant. The entire universe was everywhere as hot as the surface of a star at the time of the CMB, so any evidence of galaxies forming before that is surprising.
The surprisingly high uniformity of the temperature of the CMB — isotropic to roughly one part in 100,000 — is one of the reasons the Big Bang model replaced one of the older competing hypotheses (continuous creation IIRC).
So it is in fact the case that everything cooled very very uniformly and I'm not sure why you think otherwise?
I'm also not clear what you're saying with
> so we should see a transition somewhere
Given the CMB is itself the transition that we see.
> Sometimes, somewhere there must be a galaxy past CMB.
I think here you're mixing up space and time.
It's reasonable (please permit my use of conventional language rather than 4-vectors) to assume that a galaxy exists on the other side in space of the CMB as we see it now, but that happens at a point in time after the recombination epoch began and space became transparent, and light from that event hasn't reached us yet; when it does, the apparent distance of the CMB will be large enough for the galaxy to appear on this side.
Are you familiar with light cones and the convention of one space axis and one time axis? It might help you visualise it if you draw what's going on.
GLASS-z12 is 33.2Bly away from us. It should be behind some of the CMB produced by BB, isn't?
> Given the CMB is itself the transition that we see.
In BB model, CMB emitted by hot plasma. Where it is, that plasma?
In steady universe model, CMB is light with z=1000, emitted by distant galaxies, in range of 4Tly. It explains high uniformity of temperature. It's like the temperature of a water stream from underground: it's uniform across a climate area because underground temperature averages seasonal temperature shifting.
The latter is what we're talking about when we say the CMB is about 13-point-whatever billion years old.
The difference with the other number is that the universe got bigger in the meantime, and that's where we recon it is now.
> Where it is, that plasma
The plasma itself?
Everywhere. The whole universe, including here.
The bit we see?
An echo made of light emitted at the last moment in time that it stopped being plasma — the light from the plasma that was here is now as far away from us as the plasma that caused the light we can see.
These numbers means that nothing can travel at FTL speed except this galaxy. It travelled 20Bly in 13By at the speed of 1.5 c. Extraordinary claim requires extraordinary evidence. Where is the source of energy for this FTL galaxy? Why this galaxy is not ripped apart into ball of gluon plasma?
Echo requires something to reflect of. Moreover, echo will be an order(s) of magnitude weaker and will have a stamp of the reflective surface on it properties.
In bread analogy, sugar is the source of energy and CO2. In balloon analogy, new air is added to balloon (with lot of turbulence). What is added to our Universe, which causes the inflation? Where we can see it?
In case of Steady Universe model, light just changes it's properties over time, for example, because gravitational waves are stretching photons and photon beams. Gravitational waves are produced by massive objects, which are orbiting each other.
> What is added to our Universe, which causes the inflation?
It's a free parameter in the equations, just like the initial value for the energy in the space or the baryon number.
Or the number of space-like and time-like dimensions.
Or their inherent topology.
Not that it matters, as the point of what I suggested is that it's an analogy for all objects within the space observing the same relationship, and the implications thereof.
> Where we can see it?
In the relationship between distance and redshift. More distant objects move away faster, the further away the faster they move on average, and that relationship best matches "accelerated expansion" than any other model.
Or, more locally, it's (perhaps by coincidence) about the right level to explain the moon's orbit slowly getting bigger.
> In case of Steady Universe model, light just changes it's properties over time, for example, because gravitational waves are stretching photons and photon beams. Gravitational waves are produced by massive objects, which are orbiting each other.
Great!
Unfortunately for you, those gravitational waves can't act anything like the ones predicted by GR which we've actually observed, because those are far too weak (or spacetime too 'stiff', IIRC).
GR has known weaknesses, to be sure, but they're all annoying beyond any observations we've been able to make, and people really are looking as it's considered both important and prestigious to find a way to tie it and quantum physics together properly.
In the meanwhile, the same equations for GR describe the (just about) detectable gravitational influence your body has, and the various demonstrations of gravity influencing the flow of time and path of nearby light.
IIRC, the best atomic clocks are just about at the level where an extra 100kg sitting next to them can change the last digit relative to another otherwise identical clock, but I'm not sure how long you have to sit there.
They're definitely good enough for it to matter which floor of a building you put them on.
> Unfortunately for you, those gravitational waves can't act anything like the ones predicted by GR which we've actually observed, because those are far too weak (or spacetime too 'stiff', IIRC).
Let's play with numbers. Two kinds of gravitational waves are claimed to be observed: 1) HF waves by LIGO/Virgo and 2) LF ones by NANOgrav[1].
I assume, that the meter is defined as c1s/299792458 in steady vacuum*. Same for the second. I assume, that speed of light can go down only, in other words, speed of light cannot be higher than c.
Gravitational wave background strain amplitude calculated to be ~ 2.4E-15 y-1. For simplification, I assume average slowdown (stretching) of light to be 1E-15 per year.
LF gravitational waves are quite powerful, with strain amplitude 2.4E-15 y-1, but their low frequency does almost no impact to the wave length of light. In 1 billion of years, wave length will be enlarged by up to 1,0000024.
HF gravitational waves are much weaker, say 1E-21, but their high frequency, say 20kHz, may increase wave length up to 1.88, which is much closer to expected Red Shift of 7.
a pair of objects orbiting 24 thousand times per second.
This happens when black holes or neutron stars merge and that's it; this means you don't have enough of them to do what you're claiming, not even if I trusted what looks suspiciously like you blindly asserting without evidence how much they should alter wavelengths.
The effect of gravitational waves is barely anything even on the LIGO detector, and they need to use a squeezed quantum state to even notice because it's much smaller than the wavelength of the light even over the length of the entire beam-line.
Also, gravitational waves don't redshift the photons, they change the length of the path the photons take.
-
And as LIGO, NANOGrav etc., are relying on a prediction of the exact same GR equations that also lead to the big bang etc., you trying to shoehorn that in is roughly analogous to a Young-Earth Creationist talking about carbon dating.
> Or by 24 thousand pairs orbiting 1 time per second,
no, and for the same reason you can't use the output of a quarter million 2.45 Ghz microwave oven magnetrons to produce monochromic teal light (612500 Ghz).
The maths is basically equivalent for EM and gravity waves, except for the constants.
Well, that and the fact it's changing the space-time through which the waves themselves propagate, but the effect is usually small enough to be barely detectable even when you want to.
> Yep, more length to travel - larger wave length. :-/
no, same wavelength, going further on one half of the cycle, then not as far on the other half of the cycle. Same wavelength within the space, it's the space itself which changes.
> I had a discussion about that recently. I have no power to repeat the discussion. You can find it in my comment history.
TBH, that would be a colossal waste of my time. I'm only even bothering to reply to this this now because discussion is supposed to be helpful while I learn things.
> no, and for the same reason you can't use the output of a quarter million 2.45 Ghz microwave oven magnetrons to produce monochromic teal light (612500 Ghz).
Why we need monochromatic light? Gravitational wave background is just noise. A lot of orbiting objects in a galaxy will produce steady noise, due to interference. It's easy to check just by putting a bunch of wave generators with different frequencies in a same pond, and then move. Interference between waves will create noise with higher frequencies than original.
Even small effects are producing significant results over large periods of time. 1 billion years is 31.5E15 seconds.
If we integrate over all frequencies of gravitation noise floor, then we may have a number, which will explain a part of red shift.
More over, gravitational noise is important for Pilot Wave theory, because it may explain the source of energy for the pilot wave.
> no, same wavelength, going further on one half of the cycle, then not as far on the other half of the cycle. Same wavelength within the space, it's the space itself which changes.
It implies FTL speed at the second half of the cycle, which is impossible. If wavelength of light will be enlarged, then it will stay enlarged, because light traveling at c, so c-delta is possible, but c+delta is not.
> TBH, that would be a colossal waste of my time. I'm only even bothering to reply to this this now because discussion is supposed to be helpful while I learn things.
I have the same filling. I only reply because my pleasure to talk with you overcomes the inconvenience of Hacker News.
Maybe we should switch to email, or to a wiki with a proper set of tools for scientific discussion.
You have to be careful with what you mean by "distance" at cosmic scales. Space is expanding with time, and there are several different definitions of "distance" that give very different results at cosmic scales.
The best "distance" measure here is simply redshift. GLASS-z12 is at redshift z=12, as the name suggests. The CMB is at redshift z=1100, so it's father away.
In fact, for very straightforward physical reasons, no light can reach us from beyond the CMB. The universe was opaque before the time of the CMB, because it was ionized and dense. Before the CMB time, photons could not travel very far at all before they hit an electron and were scattered.
Nobody pointed to a source of energy for this "expansion" of "space". Usually, coordinate system doesn't expand with time. An extraordinary claim requires extraordinary evidence.
Yes, CMB emitters are much further away, at a distance of about 4Tly, while BB claimed to be just 14By ago. Your claim, that CMB is produced by BB, requires a lot of stretching.
There's no point in arguing about this here. There's a very well defined, mathematical theory called General Relativity, which explains gravitational phenomena from Mercury's precession all the way to the expansion of the Universe.
If you take the time to learn General Relativity, and to learn how to apply it to cosmology, you will see that there are rigorous mathematical answers to the various questions you're raising.
I want to point out that this isn't esoteric stuff that only a few people understand. General Relativity and cosmology are part of a standard undergraduate physics curriculum. It only takes a few years of study, starting from Physics 101, to get to the point where you can derive the answers to all your questions from scratch.
Doesn't even need that much — their questions so far are at my level, and I keep messing up the much simpler special relatively questions on brilliant.org
"How" this specific expansion happens is an open question — not because nobody has any idea, but because we can't distinguish between three of them and a forth leads directly to the unsolved challenge of combining GR with quantum mechanics.
No, this is not an answer, because it breaks number of laws of physics, such conservation of energy. It looks like an excuse that an answer. It's just heavy stretching of the evidence until it fits the BB model of evolution of Universe.
Static Universe model of evolution doesn't requires such stretching: CMB is just light of distant galaxies. End of story.
>No, this is not an answer, because it breaks number of laws of physics, such conservation of energy.
THE WHOLE POINT of GR is that it explains things that "classical" physics did not, while also explaining everything that classical physics did. Nothing in GR "breaks the laws of physics" because GR largely IS the laws of physics now.
If you want to throw away GR by using a "Static Universe" theory, you have to re-derive a hundred different solutions to problems you bring back into physics by doing so. Einstein literally TRIED to put a static universe into GR because he thought it felt better, and turned out to be dead wrong!
In terms of "what drives the expansion", to us, within the universe, it's just what we see. It could very well be that it's a property of whatever "substrate" or "Stuff/emptyness" that a "Universe" exists in, if "exists" even makes sense in that context. It could be a completely unknowable to us thing. There are very likely phenomena and questions that we cannot ever answer, because we simply have no way of probing them.
All we know is that the way GR says to do the math works out really well for like 99.99% of things, and if you want to come up with a model that doesn't allow space to change "size", you have a shitload of math left to do at a minimum. If you want to understand how we got here, you have 400 years of physics history to read up on. None of this is about the "correctness" of GR either. It just makes the best predictions so far, and in science, all that matters is who makes the best predictions. Want to supersede the GR model? Just predict something correctly that GR cannot, while also predicting everything else correctly.
> If you want to throw away GR by using a "Static Universe" theory, you have to re-derive a hundred different solutions to problems you bring back into physics by doing so.
GR will be a special case in a new theory, which will explain laws of Universe better, which may join together GR and QM. If a formula does a good job, then it will be used anyway. We are not throwing away Newton physics just because GR does a better job in some cases.
> In terms of "what drives the expansion", to us, within the universe, it's just what we see.
Are you talking about a "light sail" effect? Yes, EM radiation creates pressure on dust particles, which pushes them away, but gravitation doesn't let it go. The same effect happens at size of galaxy. I'm not sure about superclusters, but it looks like we are falling into Great Attractor then into Shapley Attractor with all that dust.
So yes, this is possible, but EM radiation must be stronger than gravitation.
> It just makes the best predictions so far, and in science, all that matters is who makes the best predictions.
Predictions are very important, because they allow to prove or falsify a theory, but this is a game for theoretical physicists only. There is only one reality, which can be describer in many ways. Many different formulas can fit the same data. Many different techniques can be used to achieve the same result.
Moreover, every formula works in a range, then it doesn't work. Pi is an irrational number, which cannot be reproduced correctly in reality, thus every formula or path, which contains the irrational number, can be reproduced by physical reality with limited precision only. Multiply the error by many iterations, and new physics will emerge in the same place.
The only way to prove a theory, as I see it, is to make physical demonstrations at human scale, an analog, and then study it.
Hydrodynamic quantum analogs allows us to see pilot wave at work, so no mysteries in double slit experiment anymore: it just self-interference of the pilot wave. The same can be done for space effects.
It's easier to make computer model, to make predictions, but to make a correct model, we need to understand physics first. Egg and chicken. In case of a physical demonstration, nature performs all these calculations for free, automatically. Even when they are partially correct, they are still helpful.
> this is not an answer, because it breaks number of laws of physics, such conservation of energy
GR doesn't conserve energy. What follows is a bit beyond my level so I may be misremembering, but IIRC Noether's theorem is that conservation laws are always identical to some symmetries, and the symmetry for energy (time?) just isn't true in GR.
(I don't think it's even true in SR because space and time are observer dependent, but at least in SR you can get a different conserved quantity because all observers agree on a space-time interval; but as I implied in a different comment where I mentioned brilliant, this is my hobby not my profession).
> CMB is just light of distant galaxies. End of story.
The CMB is a perfect blackbody. Galaxies are far from a blackbody. Your explanation fails if one knows even a tiny amount about astronomy.
Before you criticize Big Bang cosmology, you should learn the theory. That means studying General Relativity, learning to derive the Friedmann Equations, learning about the (utterly overwhelming) observational evidence for the theory, etc. Then you'll be in a position to ask intelligent questions about the theory.
I promise you that if you learn the theory, you'll understand that the questions you're asking either don't make sense or have obvious answers. For example, conservation of energy does not hold in General Relativity. You keep saying that expansion is an ad hoc assumption that breaks physical laws. However, if you solve the Einstein Field Equations, you'll see that the universe must be either expanding or contracting. This fact bothered Einstein so much that he tried to modify General Relativity to get rid of it, something he regretted when observational evidence firmly established that the universe was indeed expanding. This was all the way back in the 1920s, and the evidence is so overwhelming now, a full century later, that it's impossible to deny.
> The CMB is a perfect blackbody. Galaxies are far from a blackbody.
CMB is not emitted by a single galaxy or even group of galaxies. It's light of trillions of supeclusters, like our Visible Universe, averaged. I expect that almost any local unevenness should be polished out when averaged over such large area and distance. We are not seeing stream of photons from individual emitters, we see random photons from extremely huge range of emitters at extremely huge range from us.
If clump together all radiation from all our Visible Universe into single stream of photons, then we will see something very similar.
> For example, conservation of energy does not hold in General Relativity.
If you average a bunch of different types of galaxies, you do not get a blackbody.
Do you know what does give you a blackbody? An optically thick medium with a uniform temperature, which is what the CMB "last scattering surface" is.
I just have one question for you: do you think that physicists are all a bunch of dunces? You're doing extremely simple questions. Do you think that physicists haven't worked out the basics of the theory? Again, instead of raising extremely simple objections, your time would be better spent understanding the theory first.
>> For example, conservation of energy does not hold in General Relativity.
> Then something is wrong.
Energy conservation only holds locally, when space is nearly flat. The true conservation law in General Relativity is more complicated (energy-momentum conservation).
> If you average a bunch of different types of galaxies, you do not get a blackbody.
Black body averages emission of trillions of trillions of atoms. Why it will not work for emission of trillions of trillions of galaxies? Can you prove that?
> Energy conservation only holds locally, when space is nearly flat.
> Black body averages emission of trillions of trillions of atoms. Why it will not work for emission of trillions of trillions of galaxies? Can you prove that?
No, that's not what a blackbody is. A blackbody is an optically thick medium in thermal equilibrium. Galaxies are not blackbodies (not even close), and when you average a bunch of non-blackbody spectra, you don't get a blackbody. You'll get a spectrum with all sorts of atomic and molecular features. There is actually something called the "Cosmic Infrared Background," which is caused by distant galaxies, but it's not a blackbody and it has much larger amplitude variations than the CMB (because galaxies are distributed in a clumpy way).
> Space is flat in all directions.
Globally, spacetime is not flat (i.e., it is not Minkowski). Spacelike surfaces of constant coordinate time are flat, but the whole manifold is not flat. If this is all a bunch of gobbledygook to you, then you need to learn the basics of General Relativity.
> A blackbody is an optically thick medium in thermal equilibrium.
Black body can be simulated by a cavity with small hole, so incoming light will be scattered and fully absorbed, with zero reflections. In case of CMB, light from our Visible Universe will never return back to us, because it will be too weak and too stretched.
Moreover, this is really big journey for a photon, with very high probability to hit something on the way to us, so we may see a large portion of re-emitted EM radiation instead of the original light.
What is the difference between black sky and black body?
> Galaxies are not blackbodies (not even close), and when you average a bunch of non-blackbody spectra, you don't get a blackbody. You'll get a spectrum with all sorts of atomic and molecular features.
Emission from multiple random objects can be approximated as black body radiation, even when they are not in thermal equilibrium with their surroundings.
Moreover, we use statistic to distinguish between different emitters. In case of CMB, years may pass until we receive second photon from a same galaxy. Statistic doesn't work in such extreme cases, unless we will point an antenna in the same direction for a millennia or even longer.
> There is actually something called the "Cosmic Infrared Background," which is caused by distant galaxies, but it's not a blackbody and it has much larger amplitude variations than the CMB (because galaxies are distributed in a clumpy way).
CIB emitted mostly by stars and dust particles, which are hit by the star light, which are much closer to us than CMB emitters. We may get different picture from outside of our galaxy, or when we filter out local emitters.
> Spacelike surfaces of constant coordinate time are flat, but the whole manifold is not flat.
You are talking about model. Can you map your model back to physical reality, please? As I understand, you are trying to tell me that a point in the non-flat space-timecan have less or more neighbourhood points that in flat space time. In other words, wormholes or space-bubbles are possible in your imagination.
> then you need to learn the basics of General Relativity.
I'm too stupid to understand this great theory. I need simple explanations.
(I suspect also GR, but not for any reason you give — the maths presumes no singularities from what I've been told, and yet they happen anyway with easy initial conditions).
For the broader point, if there were galaxies trillion of light years away whose light had time to reach us, they'd be trillions of years old by now, and therefore we'd expect a lot more galaxies near us to be that age too.
We don't see any evidence of nearby galaxies that old; denying the conclusion means falsifying the hypothesis.
Also, they'd have to go on forever to not look clumpy, and then we would still need a source of red-shift to stop them being as bright as the surface of a star in all directions.
I know that. I'm heretic. Moreover, I'm too stupid to understand all these great theories. I need simple explanations.
> For the broader point, if there were galaxies trillion of light years away whose light had time to reach us, they'd be trillions of years old by now, and therefore we'd expect a lot more galaxies near us to be that age too.
Of course, not. Space is mostly empty. If elementary particles are generated constantly from pure energy (which doesn't violate laws of conservation) just of pure luck at cosmic scale, then light from distant neighbors slowly pushed this newborn dust into the center of a gigantic void, where it started to concentrate. In such case, we will have huge gap of void between our region of space and our neighbors.
> Also, they'd have to go on forever to not look clumpy, and then we would still need a source of red-shift to stop them being as bright as the surface of a star in all directions.
Surface area of a distant object reduces at r^2, while brightness of the distant object diminishes at r^3. Moreover, the probability of hitting something grows with d^1, so total brightness diminishes with (d^3*d)/d^2 = d^2. The number of objects in the sky increases with area = d^2. So, d^2/d^2 = const. I see no infinity. At average, the brightness of sky must be very similar in all directions. The larger the distance - the closer to average brightness must be.
CMB must be almost ideal.
> If elementary particles are generated constantly from pure energy (which doesn't violate laws of conservation) just of pure luck at cosmic scale, then light from distant neighbors slowly pushed this newborn dust into the center of a gigantic void, where it started to concentrate. In such case, we will have huge gap of void between our region of space and our neighbors.
Requires simultaneous behaviour from all directions at great distances while also not having that behaviour here, and also having us being really close to the physical center of this phenomenon rather than off to one side — even a fraction of a percent would be easily noticeable given the CMB is so close to the same in all directions; we see a red/blue-shift dipole from us moving at 370-ish km/s relative to it's comoving rest frame, so that's the scale of fractional away-from-perfect-centre you'd have to explain.
> Surface area of a distant object reduces at r^2, while brightness of the distant object diminishes at r^3.
If space was flat, which is your presumption, those would both be 1/r^2.
> Moreover, the probability of hitting something grows with d^1
You should be able to tell that's wrong by it being an unbounded function, when probability stops at 1.
> If space was flat, which is your presumption, those would both be 1/r^2.
You forgot about red shift, which also diminishes the source, so, very very roughly, it's 1/r^3.
> Requires simultaneous behaviour from all directions at great distances while also not having that behaviour here, and also having us being really close to the physical center of this phenomenon rather than off to one side — even a fraction of a percent would be easily noticeable given the CMB is so close to the same in all directions; we see a red/blue-shift dipole from us moving at 370-ish km/s relative to it's comoving rest frame, so that's the scale of fractional away-from-perfect-centre you'd have to explain.
When we are in a fog, we always in the center of the visible area. With such larger distances, the probability of hitting something for a photon is very near to 1, even when interstellar space is extremely clear (hard to calculate exact numbers for me).
> You should be able to tell that's wrong by it being an unbounded function, when probability stops at 1.
When we see direct light, then probability is below 1. When don't, then it's 1. :-/
> You should look up Olber's paradox.
You should look at the picture of the darkest spot on the sky: it's full of stars. :-/
> Nobody pointed to a source of energy for this "expansion" of "space".
Several have been made, the suggestions have issues.
> Usually, coordinate system doesn't expand with time.
Define "usually". Do you have experience of other universes?
> An extraordinary claim requires extraordinary evidence.
Indeed, but this comment box is too small to do the evidence justice.
Edit: that's unhelpful in retrospect, so I suggest the Youtube channel "PBS Space Time". The videos build on each other, so start at the beginning and work through the back catalogue.
> Yes, CMB emitters are much further away, at a distance of about 4Tly,
> Define "usually". Do you have experience of other universes?
I have experience with coordinate systems. I can bend or expand space-time on my computer all day long, to simulate reality, but I cannot do that in the real world at all.
> Indeed, but this comment box is too small to do the evidence justice.
Looking for the paper or a blog post! However, I suspect that you will just stretch evidence until it will match your model.
> I have no idea where you got this belief from.
Just by looking in the window, I see that some object are close, other are far away, then even further away, and so on, up to 4Tly. Nothing extraordinary. No Big Bangs, no FTL speeds, no hidden sources of energy of epic size, just ordinary physics.
Reminds me a bit of my dad; he did radar simulation for military IFF and one of his work anecdotes was about increasing the number of decimal(!) digits of pi the software used.
He stopped boasting about that when I pointed out the extra digits were less relevant than the curvature of spacetime caused by Earth itself.
> Just by looking in the window, I see that some object are close, other are far away, then even further away, and so on, up to 4Tly
I had dreams like that once. Woke up to find I was suffering from testicular torsion.
If you seriously believe you can see 4e12 light years through your window, that's probably hallucinogens of some kind (not necessarily intentional).
I 100% sure that I cannot bend or stretch imaginary coordinate system outside of my imagination. Can you point to real physical process which causes stretching or bending of the mathematical abstraction?
> If you seriously believe you can see 4e12 light years through your window, that's probably hallucinogens of some kind (not necessarily intentional).
I cannot see objects smaller than a star or galaxy with naked eye. However, we can see light stretched to the microwave range.
> Can you point to real physical process which causes stretching or bending of the mathematical abstraction?
"General relativity" as we keep telling you.
> I cannot see objects smaller than a star or galaxy with naked eye.
Only a factor of about a trillion in the size of those two things.
> However, we can see light stretched to the microwave range.
With your eyes? No. And certainly not through your window, whose own thermal emissions relative to the CMB makes your previous claim roughly as unphysical as saying you can look through the sun's photosphere to see Jupiter during an occultation.
> Sometimes, somewhere there must be a galaxy past CMB.
If there is we'd have to wait for the light from it to get to us, by which time the CMB will have receded further and it would then be in front of the CMB.
A transition from plasma to the cold mater in the form of galaxies we see.
> Why not?
As you see, there are big clusters everywhere. It means that some regions were cooler from the start, to form these cluster in so short period of time. It means that regions around them were hotter, thus they should emit light longer.
> If there is we'd have to wait for the light from it to get to us, by which time the CMB will have receded further and it would then be in front of the CMB.
300My is a short period of time. Why they cannot sometimes overlap?
Maintain low expenses, be OK with going down in life quality, be willing to burn through your life savings and be OK if you lose it all.
I did it once, now doing it for the second time. I think most people will not bear it, but for me it feels like the only natural thing to do.
I can never imagine enjoying either running a hyper-growth VC funded company or being an employee, and I realize most people are not like that.
So on that end, maybe ask yourself if you were OK with cutting costs like losing the car, moving to a smaller apartment (even back with your parents) etc.
and be happy about it even if your company flops.
Same. I really struggle to learn anything which I can't see a practical use for.
Just as an example, in high school learning trigonometry was really difficult for me, like why would I even care about finding an angle in a triangle, etc.?
Only once I studied physics or game dev, this has started to become relevant, and then studying it got SO MUCH easier.
It's mindboggling to me that every teacher doesn't just debut the subject with videogames as a reference.
"Alright everyone, let's make a video game character out of triangles".
"Let's make a little cannon that you can change the angle of. How do you calculate the angle? Funny you should ask.."
"Now let's learn how you'd make the fireball move up and down as it travels. That's a sine wave!"
Every single student understands the basic concept of a game visually, even if they don't play them regularly. It's just a perfect frame of reference and context for applying the concepts in 2D, and then in 3D. And it's so easy to help the students understand how easily those concepts get extrapolated to other things (engineering, sports, whatever).
Totally! One of the first thing I did after learning Newton's law of gravity, was to write down a small simulation of planets in orbit and how they "dance" around each other. This little exercise totally blew my mind and the code was really simple to code.
There's probably an untapped opportunity here, but ed-tech is such a difficult industry.
I'm sure someone actually working in ed-tech will correct me, or perhaps even laugh me out of the room, but I still believe in what I figured out around highschool: that edtech, particularly "educational games", have it all backwards.
Kids aren't stupid. If you take the usual boring curriculum with choreful exercises, and try to "make it more fun" by half-heartedly sprinkling in some colors, characters and cheesy stories, it will backfire spectacularly - kids will see you're just trying to trick them, and not even putting much effort into it.
The right way is the reverse: you need to make something honestly, inherently fun, but design it so that it educates users/players as a side effect. Take Kerbal Space Program: it's not designed to be an educational game, but it's fun, and models real-world physics well enough that you get 12 years old researching and understanding the math of orbital mechanics, all because they'd like to do better than "point roughly half-turn ahead of the Moon and go full throttle", and they'd like to not run out of fuel on the way. Or, look how Minecraft is tricking kids into learning electronics, boolean logic, low-level programming, etc.
(I'd mention Factorio, but I think it's a wash - any gains society gets from the game educating kids are cancelled out by the amount of productivity loss the mere exposure to this game inflicts on software devs.)
(EDIT: or, remember Colobot? A very simple third-person perspective game that had you find and refine resources to build robots, which then you used to kill some big bugs. The twist being, instead of controlling the robots like in a shooter, you had an option to program them in a Java-like DSL, inside the game. It was a great way to organically learn programming. The IP owners later made a "fork" of the game, Ceebot, that was pretty much the same, except it focused on teaching you to program robots instead of having fun exploring and shooting stuff. Predictably, that simple change of focus made the game flop.)
It doesn't even have to be a game: leave a kid in front of Google Earth, and they'll learn geography much faster and much more thoroughly than they would from a globe or a book. Not because the software is better at teaching, but because the kid is just messing around with a virutal model of Earth, and learning stuff along the way.
Etc. Etd.
I think it's a tough sell to adults, particularly parents and educators - that if you want to motivate kids to learn, you need to... stop trying to motivate them to learn. Give them something that's honestly fun, involving or benefiting from real-life knowledge and skills, but actually trying to teach them - and then trust that they'll pick that knowledge up on their own.
They call these kind of games "chocolate covered broccoli" and I totally agree.
I think games, have lots to teach, but that most of the time they are a catalyst for learning or inspiration to learn, but on their own, they will rarely actually teach you. It's hard to put the finger on it, as for example, I'm not a native English speaker, but I learned and practiced most of my English from playing video games, and they were the catalyst to make me WANT to learn English, but they didn't exactly *teach* me English.
Another part of it, is I bet if you sample today's scientists and engineers at places like NASA, you'd probably find that a lot of them loved watching Star Trek/Star Wars as kids. So while sci-fi hasn't taught them how to work with Schrodinger's equation, it probably had a major part of what sparked their motivation to get started. Games probably do that too, and then some, thanks to interactivity.
Thank you! Not only I 100% agree with you, you've also managed to provide a few terms and phrases I've been missing, which could've cut my previous comment down to 1/4 of its size, without loss of meaning. Specifically:
- "chocolate covered broccoli"
- "catalyst for learning"
- "inspiration to learn"
> I learned and practiced most of my English from playing video games, and they were the catalyst to make me WANT to learn English, but they didn't exactly teach* me English.*
English is my second language, and I've also learned most of it from video games. Mostly from exposure, but initially through focused effort - I still vividly remember that time when I was maybe 10 or 12 years old, when I made screenshots from loading screens in Star Trek: Generations, and printed them out on paper, one by one, directly from MS Paint, to take back into my room and meticulously translate the story text on those screens, looking up every single word in an English->Polish dictionary. I also remember keeping that dictionary around when playing Fallout 1. The need to understand the stories and dialogues in games is what bootstrapped my English.
> I bet if you sample today's scientists and engineers at places like NASA, you'd probably find that a lot of them loved watching Star Trek/Star Wars as kids. So while sci-fi hasn't taught them how to work with Schrodinger's equation, it probably had a major part of what sparked their motivation to get started.
I agree. And Star Trek is, in fact, what got me interested in STEM. I owe my entire career and most of who I am as a person, to early exposure to captain Picard and the adventures of Enterprise-D.
(A lot of my early STEM self-education was driven by trying to understand the so-called "technobabble", which - at least in TNG - actually made sense. Probably because, in those days, they had proper scientific advisors.)
> Games probably do that too, and then some, thanks to interactivity.
Yup. I mentioned KSP for a reason - not only have I read the accounts of parents impressed by how much advanced math and physics their 8-12 years old kids can pick up, just for the sake of getting better at the game, but myself I also learned these things for the same reason. While Star Trek is what got me interested in space in the first place, KSP is what got me to finally grok how orbital mechanics and rocketry work in reality. It also made me no longer able to fully enjoy any space travel fiction, except for diamond-hard sci-fi.
I should probably give KSP a try again. I guess there's an initial threshold I got to power through first, as I got a bit exhausted after the first mission hehe.
I'm actually working now on a game of my own, with themes of science, and it's indeed a game-first approach rather than an educational game, but I do hope to maybe inspire some ideas and motivation with at least a few players.
I totally believe there's a lot of untapped potential in this area, and advancing towards cracking learning motivation + capabilities could have a huge impact.
> I should probably give KSP a try again. I guess there's an initial threshold I got to power through first, as I got a bit exhausted after the first mission hehe.
What made all the difference for me was a mod (Kerbal Engineering ...something?) that calculated ∆v for each stage as you were building your rocket. Coupled with a ∆v "subway map" of the game's solar system, this solved the problem of running out of fuel half-way through the mission. I eventually learned how to do the math on my own, but I would've given up long before that happened, if not for this mod. It's been some time since I last played KSP, but I hear that this functionality is now built into the stock game.
Good luck with your game! Give me a shout if and when you need someone to play-test it :).
Back when I studied these videogames were much simpler. I was explained instead calculating areas and volumes for various functions and that was enough for me to get it. The thing is that not everyone was confused and some can take in theory without a practical application. They’re different modes of thinking and I appreciate both, I just happen to fall in the practical group.
In primary and secondary school, I had troubles with math - mostly caused by me not doing homework exercises and generally avoiding work (probably an early indication of an issue that took 20 more years to diagnose...). It all changed when I got interested in gamedev - suddenly, I've caught up with most of the material I was bad at, quickly learned trigonometry beyond the secondary school program, and then some basic vector and matrix algebra - and I distinctly remember it all starting with a simple problem: how to make a sprite rotate and move in circles?
Couple decades later, I still have a kind of theory+applications mindset: I always seek to generalize and abstract, but I feel lost when presented with a new abstraction without any context. Over the years, I realized I learn and understand things most effectively by seeking out answers to the question: why?. Not in the sense of, "what will I ever use this for?", but in the sense of "why was this invented?", "what were the problems people who invented it were trying to solve?". I trace the topic back in time until I find the point where the "why" and "how" are both apparent, and then go forward from there.
I would love to have some sort of statistics on what the proportion of this feeling is. My suspicion is that the practical approach is probably about 90% of the population (who is willing to learn math at all). Would be helpful in trying to figure out how to tune learning programs. (I say this as one who is perfectly content to learn the theory directly and with little-to-no practical motivation, but my impression is I'm very much in the minority on that.)
I was going to say that the curriculum is tuned in favor of those who can just learn by theory, but then I realized that's not even true. It's tuned in favor of those who will simply swallow it without any idea what it is for; it is neither contextualized in terms of what it is practically good for, nor is it contextualized in terms of theory. It's just... there.
I’d be curious to see that as well. I loved math until it became too abstract for me to grasp so I lost interest in it. And that worked pretty well as a self selection for the field, well, a large part of it. I wouldn’t want to be in the academia anyways…
> I really struggle to learn anything which I can't see a practical use for.
That's a close-minded, ignorant world view. Much of the world's most important advancements were made before any practical use could be seen. Why do you think that way?
> Much of the world's most important advancements were made before any practical use could be seen.
In a sense, yes. But usually this was kind of accidental - as in, people making those breakthroughs weren't doing it because they loved manipulating abstract symbols, or believed that someone, somewhen will find it useful; rather, they had some immediate-term reason for doing the work - a problem to solve, a person to impress, or just doing it for shits and giggles - and only later it turned out their work was the key to something transformative.
I have a similar "mental make" as GP too. Over the years I realized that for me, it's not about practical use to me - it's about knowing why something was invented, what problems the inventors were trying to solve. Learning the historical motivation "grounds" the concept for me, and makes it much easier to understand.
It's just the way my mind works and motivated. Motivation is a very elusive feeling that I did not find easy ways to manipulate.
It's not as if I'm totally blocked from learning stuff with no clear purpose, but it will require much more mental capacity that is often difficult to muster in the day-to-day routine.
Another example, is I did try to learn what I perceive as totally theoretical math such as "prove that there are infinite primary numbers" which was a nice idea to entertain, but it didn't really make me want to dig in further.
On the other hand, learning about linear algebra in the context of machine learning, suddenly got Linear Algebra a lot more interesting and easy to learn.
Makes sense. Somewhat related --- I find procrastination to be a very similar feeling. I know what I should do, but I feel compelled not to do it, for whatever reason.
I think procrastination and what you are describing are slightly different, though, because procrastination stems from stress and emotions for me, whereas with what you describe, it doesn't sound like you have to be stressed to experience it.
You are shadowboxing - fighting an argument nobody is making. Someone is describing their personal experience of the world, not arguing that this is the best way to think about the world. It's an opportunity to learn about the ways that people learn things differently, if you can be curious and kind about it.
At the quality of the current output, I think players still easily differentiate between AI generated art and hand-created art. Maybe in future versions this will be less noticeable.
As a game dev, I think at this stage AI can be a helpful utility, but it does not replace a designer's touch for professionally looking games.
If these levels were used in a game I was playing, they would not certainly not stand out to me as AI generated. It's possible if I was specifically asked to try to figure out if they were AI then I would succeed, but even that I'm not sure of.
The AI stuff is a style though. I'm seeing it happening now in the art world, where the quirks of the model become part of the appeal of the work. Won't be long until a game with good enough mechanics comes along and blows up I think.
For better or worse, I agree with your sentiment, but that will probably change. Consider how many kinds of foods and clothing are mass produced; we often consider something made by hand to be precious, and even a higher value, but we have become accustomed to the tradeoffs for cheaper solutions. It may not be our generation, but it's conceivable future generations will be less inclined to differentiate as we do (if only based on the exposure to what this kind of art generation offers at an early age).
I'm not convinced this is true. The economics of cultural production are far more winner take all than the economics of food and clothing production. Higher quality work gets more of the limited attention in that economy. AI work is doomed to fail because of this dynamic.
Everything gets re-appropriated by art, from mpeg frame skips to messy bedrooms.
Many of the quirks of our technology, like audio distortion for example, quickly become key components of certain styles. I remember as a child growing up in a funny valley after the acceptance of analogue distortion but before the widespread adaption of digital distortion.
Right now I'm thinking of someone like James Gerde, where the frame-to-frame shifts of AI imagination are part of the aesthetic. I think it's only a matter of time before this effect is matched up with something that makes emotional sense, and then it will blow up.
Using it that way requires intention. Developing that intention is hard to do if all you ever do is pull the one armed bandit hoping for AI to produce what you want.
I've had the opposite experience. I find that LIFX bulbs fail far too often considering the price tag, however I've yet to find anything else that can match up to them when they work. So I just keep buying them.
From the article:
> ...This was a problem for a startup with investors anxious to see fast monetization growth.
Seems as if Duolingo had been more conservative with its fundraising, it wouldn't have needed to resort to actions that might take it further away its goal of teaching a language? Do you really need almost $200M to build a business like Duolingo?
Cars have a safety rating, I wonder if houses could have the same kind of rating?
Would it be a better situation if houses for sale/rent will have a transparent safety rating visible to tenants and contractors could choose whether they build expensive, high safety buildings, or cheaper, low safety buildings?
Might sound dystopian, but to me it seems like the preferable solution.
I know I live in an old house that would probably not fit for an earthquake, but I also know that if I want to live in a safer house, I'd need to pay more or move to a less desirable location, so I'm OK with taking the risk that an earthquake will kill me while I'm in the house.
The question is whether the market could balance itself enough so contractors don't build just crappy houses and take all the new margin to themselves.
The safety standards are the rating. Someone can build a house for "better than code" and they can advertise that too, but a "rating" here would be the standard that for example a building with X floors needs to follow to ensure it's earthquake resistant, can bear at least Y amoung of weigth, resist to Z winds, etc. The mix of all these things are what become the building standards or "code".
Otherwise to do ratings like you suggest you can only do it to mass produced things, in this case the closest would be mobile homes or prefabs, since you can actually destroy it and see how difficult it was and give it a rating.
This looks great!
In my previous company, we somehow ended up building a whole ERP around Google Sheets. Google Sheets is a very powerful tool, but the JavaScript definitely felt clunky and outdated.
A solid C# foundation for building on top of excel could probably be very useful for some companies.
I do wonder though how you can nail down a target audience for this kind of tool, seems like you'd need a special kind of tinkerer and I'm not sure how many like that are out there. In my other company, which was a small company, the ones who headed it were essentially engineers that transitioned to executive positions. I doubt there are many like that out there.
> Normally vegetarian food costs less than meat. It's because the animals need to eat (surprise surprise) vegetables! When you eat the vegetables directly instead of having the animal eat the vegetable for your, it's cheaper.
Actually, as far as I recall, a counter argument to this, is that fresh vegetables are more expensive since their shelf lives are a lot shorter. I can buy most types of meats (chicken, beef, etc.), freeze them for weeks and the taste would still be great, while fresh vegetables will normally only last for a few days.
Of course you can go for frozen vegetables, but this is only limited to some vegetables, and in my opinion, don't taste as good as fresh vegetables.
"fresh vegetables are more expensive since their shelf lives are a lot shorter"
Certainly if you have sufficient storage, it's possible to buy meat in bulk quite cheaply, some of which might even be cheaper per kg (or per calorie?) than many vegetables, but if you stick to in-season vegies and cook them sensibly (into dishes that last a while), on average they're still going to be cheaper than meat.
Plenty are in the order of $1-$2/kg in Aus. (potatoes, onions, pumpkin etc.) - I don't know any meat that cheap.
I'm no dietitian but how much nutrition there actually is per 1kg of beef compared to 1kg of potatoes/pumpkin/onions, etc.?
My sister is vegan, and whenever we have a vegan meal, I'm already hungry 2 hours after the meal. On the other hand, if I eat a burger for lunch, I might not be even hungry by dinner time. Again, I'm not a dietitian so I'm pretty ignorant about these things, but if it has to do with proteins, I think the ROI for meat proteins is going to be a lot higher compared to vegetables.
I realize this gets complicated, but just another counter argument for ROI of meat compared to vegetables.
Certainly meat tends to have much higher fat and protein density, and hence calorific density than vegetables, but the latter invariably have higher carbohydrate content (meat is essentially 0). Multigrain bread can have much the same calorific density as beef, and nuts are often considerably higher (admittedly, they're typically quite pricey per kg, though not more so than quality cuts of meat).
I've personally not observed any significant difference in the quantity of food I eat between vegan/ vegetarian/meat-based meals, though I very rarely eat meals that meat makes up more than a small percentage of. It's actually the micronutrients you need to be more aware of if you're on a strictly vegan diet, which are unlikely to make a difference in food cost (e.g. B12 supplements are about $9 for a gram, but that can last you months).
Before visiting Japan, I learned to read in both Hiragana and Katakana, but I didn't really know more than a dozen or so words in Japanese. While visiting Japan, I found Katakana to be a lot more useful, because it's commonly used and often is just English words converted to Japanese letters. I think all my Hiragana reading abilities were completely useless as I couldn't tell what I was reading.