Fundamental physics sees worlds in grains of sand and infinities in hours
economist.com
economist.com
Meanwhile, the Apple CEO received $750 million. I think mathematicians are underpaid.
I dust myself off and carry on as best I can, hoping to learn a little more than I did the day before, knowing there are good folks by my side to share the path we’re on.
But on the sheer vastness of what we didn't know, it seems like that's shrinking in relevance. There are of course dark areas, black holes, quantum gravity, and so on, but they are farther and farther at the edges of scale. Not as world-changing as discovering the second island after your own, or a continent, planet, or solar system. Each one has less practical impact.
If we were to discover with certainty that our universe were one of many, it would completely blow my mind.
A multiverse I can equally accept as not. What I would find far more incomprehensible is if we were to discover with certainty that we were the only intelligent life in the universe.
I think we were able to survive the Cold War because the threat was literally explosive: highly visible and quickly understandable. For longer term, quieter threats like climate change humanity does not appear to have the capability to avoid its destruction, or even the will to do so.
It is interesting though that maths was taught for a 1000 years from Euclid's Elements, Euclid living approximately at the same time as Aristotle, and it is still as valid today as it was 2000 years ago but physics was taught from Aristotle's teaching and it was just bonkers. Took 1000 years for someone to finally say 'wait, something's not right'
The relevant probabilities when making predictions are under the best theoretical assumptions we can make; which includes that the universe follows the same laws of physics everywhere.
It isn't very interesting to observe that, absent these, no proposition has a zero probability.
Eg., you dont get to claim that given the laws of physics it is possible to have a negative mass, because given no laws of physics, it is possible.
When you arent given any information at all, all propositions are equally likely.
Propositions like, "the universe has a maximum speed" aren't merely observational. They follow with probability-1 from fundamental universal laws of physics. If this is false, all of physics is false.
> assuming our best theories are true
Isn't that what the course of history teaches us, that our best theories usually aren't true? At one time spontaneous generation was our best theory on where frogs came from after it rained, and it was based upon our best observations at the time. I'm not sure why this particular point in time would be special. I'm not saying that the current laws of physics aren't a great way to model the universe as we currently observe it, but it doesn't mean they actually are true and we have to be open to that possibility, if something that doesn't fit our current models and laws appear. But not until then, mind you.
The proposition, "steel bars in this lab fall to the earth" being /false/ doesn't impact essentially any theory of physics if there are magnets in the lab. If you exclude every possible alternative, leaving gravity, then the proposition being false invalidates basically all of physics. Including the fundamental assumption that the laws of the universe are universal.
So the question is what theories *require* a proposition to be true, in that, they logically entail it.
When this is made clear it should be obvious that "maybe the maximum speed of the universe is different" is very very different to the claim, "maybe mars is habitable".
Many lay people, entirely ignorant of the best theories we have, do not understand that the former requires extraordinary levels of evidence to take seriously; while the latter requires almost none.
This type of "unknown unknown" argument often fails to make this distinction for the sake of making some fantasy as plausible as some possible reality.
EDIT: Umm, it was a joke. I don’t claim it was funny. But...just a joke.
www.bigcircusmodel.org
I'm not trying to discount it, but that home page with 12 photos of various galaxies, and then 4 blurbs of text, then a full screen YouTube video just feels "unscientific".
The website you link poses a number of unsubstantiated claims without any answer to the numerous problems it raises.
Then he links to this hilarious notebook; https://colab.research.google.com/drive/1K1qoUFvqZp1fWbpcKJW...
I don't mean to sound rude but this doesn't look like the work of someone who has spend any considerable amount of time actually studying the Universe.
- The analysis of supernovae light curves is calibrated in a way that presumes galactic recession. More detail here https://arxiv.org/abs/1711.11237.
- The 2.7 K cosmic background radiation is consistent with non-expansionary, non-big-bang models. Cosmic temperature was predicted 50 years before Penzias and Wilson. https://en.wikipedia.org/wiki/Cosmic_microwave_background#Ti...
- The mechanism for photon energy loss (can we call this "photon hubbling"?) is not scattering by free electrons. I speculate it is the cost of traveling, of a photon forging its way through spacetime. E_t / E_0 = e^(-Ht). In the act of moving, the photon is warping spacetime. It doesn't travel for free.
And, what's your view on Dirac's large numbers hypothesis?
From a four dimensional perspective—which is the correct one, let’s not forget—the distance between a photon’s emission and absorption event is always zero.
“Tired light” would require the photon to spontaneously lose energy based on the Manhattan distance of the path it takes. That distance can be arbitrarily large, sure—a photon can cover the entire universe before absorption—but it isn’t the path the photon actually takes, so it’s difficult to imagine why it would matter.
That would require the emission and absorption events location in the space to be the same would it not? Or do you mean that a photon does not experience time, so relative to the photon it simply travel instantaneously from emitting coordinate to absorption coordinate?
I think they're referring to the distance in Minkowski space,[0] where the time component and space component cancel out for light.
[0]: https://en.m.wikipedia.org/wiki/Spacetime#Spacetime_interval
ds^2 = dx^2 + dy^s + dz^2 - cdt^2
There’s a tendency to treat spacetime intervals as something abstract and possibly metaphysical, because we can’t see or touch them, and they work counterintuitively.
They’re actually the opposite. Our normal experience of 3D space is what is unphysical; the (square root of the) spacetime interval is simply distance, measured in meters. Or seconds, of course.
The literal, physical distance between an absorption and emission event is always zero. Reality is non-Euclidean. The Manhattan distance is larger than the actual distance, which is usually true anyway.
Well, I suspect I just spent a lot of words telling you something you already knew, so I’ll leave off with a book recommendation. Dichronauts, by Greg Egan.
Between that and the Clockwork Rocket trilogy, I don’t know a better way to inculcate an intuition for special relativity.
One is set in a 2+2 spacetime; the other in 4+0. The differences are instructive.
Unfortunately photon behaviour is fairly important...
The point is that I think claims like "distance doesn't exist" is the kind of thinking that comes from people lost in notation.
I know the theory the view you're saying comes from, and the weight it has in academia, but it always struck me as useless. And that whoever came up with it was lost in notation.
Not from the photon's point of view. This is very crucial and it is not because of notation or maths. The real difference is from your point of view. I know it's counter-intuitive but that's different from being useless.
Sun->Earth or Sun->Jupiter is a small beer. It is the same for photons from the CMB being recorded. For them, they have been emitted and absorbed at the same instant and experienced no passage of time or distance traveled
What are the real physical consequences of thinking that the photon is "emitted and absorbed at the same instant"?
- The analysis of supernovae light curves is calibrated in a way that presumes galactic recession. More detail here https://arxiv.org/abs/1711.11237.
- The 2.7 K cosmic background radiation is consistent with non-expansionary, non-big-bang models. Cosmic temperature was predicted 50 years before Penzias and Wilson. https://en.wikipedia.org/wiki/Cosmic_microwave_background#Ti...
- The mechanism for photon energy loss (can we call this "photon hubbling"?) is not scattering by free electrons. I speculate it is the cost of traveling, of a photon forging its way through spacetime. E_t / E_0 = e^(-Ht). In the act of moving, the photon is warping spacetime. It doesn't travel for free.
- The analysis of supernovae light curves is calibrated in a way that presumes galactic recession. More detail here https://arxiv.org/abs/1711.11237.
- The 2.7 K cosmic background radiation is consistent with non-expansionary, non-big-bang models. Cosmic temperature was predicted 50 years before Penzias and Wilson. https://en.wikipedia.org/wiki/Cosmic_microwave_background#Ti...
- The mechanism for photon energy loss (can we call this "photon hubbling"?) is not scattering by free electrons. I speculate it is the cost of traveling, of a photon forging its way through spacetime. E_t / E_0 = e^(-Ht). In the act of moving, the photon is warping spacetime. It doesn't travel for free.
This doesn’t even address this particular parent’s question. Better would be to make the comment once, where it is most appropriate, then give specific responses to other threads, perhaps linking to the one comment if it’s relevant.
No, the CMBR is not consistent with non-expansionary models. Tired light may get the shape of the CMBR spectrum right, but it fails to get the intensity right unless there's an extreme coincidence that we just happen to be living at exactly the right moment.
This was all explained in the page you think you were rebutting, so please go re-read it, this time for comprehension.
This 2001 paper uses a correction template that I think is a v1 of what SALT2 is. SALT2 probably is an "improvement" on this template, so I think by identifying a problem in SALT2, I have adequate (but not 100%) reason to think this template introduces the same bias.
Tired light is easily killed without all that, using data available decades ago, at z < 1. And this doesn't require estimation of the absolute luminosity of the SN.
The point is that the data calibration mechanism introduces bias before any analysis has been made. The data is calibrated to assume galactic recession. That's the problem.
Killing tired light doesn't require any of this. What the paper I cited did was plot the redshift vs. the rise and fall times of the light curves. This doesn't depend at all on the overall brightness of the SN. There is no need to estimate this brightness. In tired light, the result curve will be flat; in the standard cosmology it will not be. And the observations were inconsistent with tired light at 10 standard deviations, killing the theory. The SALT2 stuff you're pointing to is indeed a total red herring.
I get the feeling you're just pretending to understand all this stuff you're pointing to, for some reason.
https://physicsworld.com/a/what-is-the-lifetime-of-a-photon/
e is 2.718... d is distance of travel H' is 13.83 billion years, the continuous decay rate
Rough calculations https://docs.google.com/spreadsheets/d/13aRdc1gZmsA3F-gKt5sK...
As far as I can tell, the CCC theory says that the big bang did happen but that the universe is cyclical. i.e. once the universe reaches 'heat death' another big bang happens.
But is it the most extraordinary one?
I think more towards how we have escaped our constraints as animals:
- It's a problem to eat too much now, contrary to the experience of all creatures other than modern people.
- We no longer live in one environment. In fact we create our own, in many places.
- We don't mind if the sun goes down, we can replace it, temporarily.
- We can use energy that was captured a long long time ago.
- We don't even need to reproduce all that much to survive. It's pretty much an expectation that we'll live past childhood, it's considered a massively unfortunate tragedy if your kid dies these days.
- We can interact with people who are far away, as if they are right in front of us.
(If I had to isolate the single greatest insight in the modern world, it would be Descartes introducing the notion of number as different than "the length of a line segment". This change in perspective made possible all the math and physics that came after. This perspective is now so common as to be invisible, so for someone to see something so foundational, but so unknown, it is really remarkable.)
I will look up the specific paper where he proposed that a squared number need not represent only an area, for example.
Not sure why all the downvotes. Oh well.
Like someone else mentions in this thread, probably "humanity’s most extraordinary achievement" was standing upright in the Ethiopian plains, or language or even writing (which showed up in several parts of the world) but, again, to label a thing invented by white men (paid to develop deadly weapons, among other bad things) as the "humanity's greatest thing ever" should not be ok.
Prior to that, European advancements were heavily influenced by Islamic and Indian mathematics, such as the development of place-value numerals [3] and modern optics [4]
1: https://en.wikipedia.org/wiki/Constantinople_observatory_of_...
2: https://en.wikipedia.org/wiki/Chinese_mathematics#Qing_dynas...
3: https://en.wikipedia.org/wiki/Hindu%E2%80%93Arabic_numeral_s...
4: https://en.wikipedia.org/wiki/Physics_in_the_medieval_Islami...
5: https://en.wikipedia.org/wiki/Shin%27ichir%C5%8D_Tomonaga
I know I’m probably biting at obvious flame bait here but this comment doesn’t really seem to be in the spirit of this site’s goals for quality discourse.
That's the worst type of racism, the one so well internalised that you don't realise is there, that's what makes it more dangerous compared to the "redneck"-out-in-your-face variety.
I'm pretty sure that the author of article wasn't aware of his/her implicit euro-centric bias, he/she comes from a culture where things like "fundamental physics" are seen as representative of the group's intellectual nous (where the "group" ~= people raised up/educated in an euro-centric culture with euro-centric values), and hence as representative of the world/humanity as a whole. I take issue with this "the bestest thing made by white men" -> "the bestest thing made by humanity" transition.
Your account is old enough I’d expect you to know what dang’s about to say already, the whole “we’re steering a ship and don’t want to get sucked into dialectic black holes” thing.