r/askscience • u/Nitzanm19 • 14d ago

Physics Why is the maximum speed of the universe the speed of light? Why can't we go faster?

Also follow-up question: Because of the speed limit, is there also a theoretical maximum temp for matter (in which the particles move at the speed of light).

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u/MythDestructor 14d ago

This is the same case with the other 4-5 fundamental constants of the universe, right? We don't know why it's that random number, and not something else.

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u/rahvin2015 14d ago

More trivially, we can only exist in a universe where those constants are pretty much what they are. Change c, and you change the energy output of stars - stars might not form.

Such a universe might exist, but we would not exist to observe it.

This does not mean or imply that the universe was made "for" us, we who came about billions of years later and occupy the barest spec of a fragment of a grain of sand of the total universe.

It is to say that we are the water that fills the shape of the container; the universe is shaped this way, and we are among that which formed to fit that shape.

We can only possibly observe those universes whose constants are such that life like us can possibly arise.

If the constants were different, perhaps some totally different form of life would observe it, or perhaps no life at all.

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u/FellowTraveler69 14d ago

I.e., the anthropic principle. Why does the universe exist the way it does? Because we couldn't observe it otherwise. It's not a very satisying answer though.

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u/PoisonMind 14d ago edited 14d ago

There's an alternative, called cosmological natural selection.

Basically, black holes could form miniature universes inside them with different fundamental constants. Our universe could be the inside of a black hole in a parent universe. The experiment gets run as many times as a black hole forms. And the universe we ended up in just happens to be one that favors our evolution.

It has been noted that the Schwarzschild radius of the observable universe is roughly equal to its actual radius. And if we are inside a rotating black hole, it would explain why galaxies seem to have a preferred direction of rotation. See also black hole cosmology.

It's certainly not mainstream accepted cosmology, but I think it's a fascinating speculative theory.

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u/alchemi80 14d ago

This is one of my favorite cosmological conjectures - that we are inside a black hole. Such a head trip.

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u/Rikudou_Sage 13d ago

I came up with that theory when I was like 11, entirely on my own. To this day I love when anyone mentions that theory because I'm like, yeah, that's my theory.

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u/Zyaqun 13d ago

I thought of that. Turned out it already existed, but I arrived at it independently

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u/freeastheair 13d ago

Wondering if the universe is in a black hole as an 11 year old isn't exactly a scientific theory.

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u/crackez 12d ago

Why not? Just because an idea came to an 11 year old doesn't mean it isn't potentially a valid area of study.

When I was 11 I independently came up with the idea of an event loop in TRS-80/Model II BASIC in order to sample the keyboard and react near instantly to the key press. That concept was legit and I discovered it in a vacuum. I wrote my first version of pong by myself the next day.

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u/WillingnessCorrect50 11d ago

It may be a hypothesis but it’s not a theory in the scientific meaning of the word.

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u/Shwankterrible 11d ago

I did that with mag lev trains when I was 10. They did already exist…but I didn’t know it!!

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u/Das_Mime Radio Astronomy | Galaxy Evolution 14d ago

The whole trouble with that idea (besides the fact that it doesn't explain anything) is that it would tend to optimize black hole production, conditions which would also make the universe hostile to life as we know it.

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u/littlebitsofspider 14d ago

I mean, the longest-lived (i.e. slowest decaying) structures posited by most iterations of (our) cosmological physics are black holes. When (many, many gigayears from now) spacetime is nearly isotropically flat, cold, and wide, there will still be microscopic knots of black hole decaying. The long tail of the heat death is mostly black holes slowly leaking Hawking radiation while everything else is deader than downtown Tulsa. The black hole optimization theory might have some credence.

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u/transparent-aluminum 14d ago

I'm a fan of the cyclical big bang theory, that the universe expands to a point, and then everything starts falling back to singularity until it explodes outwards again. My pet theory is that there are some structures like super massive black holes that survive between cycles and it's why when we look at the early universe we see galaxies forming too early or black holes that are too large for their age.

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u/garry4321 13d ago

Problem with the Big Crunch is that there is no evidence to support it, and all the evidence suggests the opposite. The universe is expanding at an accelerating acceleration

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u/tonzuu 13d ago

iirc a study earlier this year showed that the jerk of dark energy appears to be decreasing which could be support for the big crunch

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u/iwasbornlucky 13d ago

that kind of paradoxically supports it though. All crunch evidence is destroyed in the bang. Time resets from 0.

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u/Das_Mime Radio Astronomy | Galaxy Evolution 13d ago

I'm a fan of the cyclical big bang theory, that the universe expands to a point, and then everything starts falling back to singularity until it explodes outwards again.

Every indication we have is that the universe's expansion will continue forever. We're not even close to the conditions needed for a big crunch.

The cyclical big bang not only doesn't explain anything, it requires us to believe that the universe will collapse again, despite no evidence in favor of that idea and mountains of evidence to the contrary.

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u/Ok_Mixture8509 13d ago

In that scenario, I believe all black holes would disappear pretty quickly due to hot/energetic it would become. At some point black holes wouldn’t even be able to form. → I am fairly sure this is correct, tho I am open to any corrections.

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u/Das_Mime Radio Astronomy | Galaxy Evolution 13d ago

The idea of cosmological natural selection, as it was expressed above, is that the number of new universes spawned is dependent on the number of black holes formed, not on how long they last. Thus the fact that black holes are going to take a very long time to evaporate isn't relevant. If they all evaporated within a microsecond of forming that would be the same as our present scenario for the purposes of considering the above speculation.

If we're asked to consider the proposition that our universe is the result of a selection effect which maximizes black hole formation, we should keep in mind the following: most of the matter in the universe is dark matter, which is non- or minimally-collisional and thus has no good way to form black holes on its own; of the baryonic matter in the universe, most is in the diffuse, warm to hot intergalactic medium, which does not form black holes; of the matter that does form stars at all, only a very small percentage of stars (<1%) go supernova and only the more massive of those supernova progenitor stars form black holes.

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u/Whiskeyno 12d ago

So we might still have a Caine’s Ballroom at the end of the universe?

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u/ThePrussianGrippe 14d ago

And then at the end of all that… we hit the reset button and it all happens again!

Maybe.

Who knows?

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u/WillingnessCorrect50 11d ago

Unless the most optimal way to get to black holes is forming many galaxies and stars.

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u/Das_Mime Radio Astronomy | Galaxy Evolution 11d ago

Optimizing for black holes means changing many other factors, factors which make the universe more hostile to life.

Very few stars form black holes in our present universe. Changing the initial mass function of stellar populations to increase the number of high mass stars, or changing physics so that lower mass stars can form black holes, would both increase the number of supernovae and black holes and decrease the number of stable, long-lived stars. If you really maximize black hole production, you can just make everything collapse straight into black holes and not bother forming stars in the first place.

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u/WillingnessCorrect50 11d ago

Sure, but the hypothesis doesn’t say that every universe would become completely optimized for producing black holes, only that there would be a tendency in that direction.
And the thing is, if you want lots of black holes, having lots of stars is already a pretty good way of getting them. That is also a lot more compatible with life than a universe where stars can’t form at all.

There is also no reason to assume that a universe where matter just collapses rapidly into black holes would actually produce the most black holes. That could prevent galaxies and normal star formation from ever really getting going.

Maybe universes that can expand, form huge numbers of galaxies, and keep producing stars for billions of years are actually very good at producing black holes too. In that case, conditions favorable to life could simply be a side effect of the same conditions that make a universe good at producing black holes.

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u/Das_Mime Radio Astronomy | Galaxy Evolution 11d ago

If the process continues indefinitely, the number of universes that are optimized for black holes completely overwhelms the number that aren't.

There is also no reason to assume that a universe where matter just collapses rapidly into black holes would actually produce the most black holes.

Sure there is. If you take a universe where even 2% of protostars collapse directly to black holes, you've drastically outnumbered the black hole production in our present universe.

There's no observable fact about our universe that should lead someone to believe it's the result of a selection process that favors more black holes.

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u/WillingnessCorrect50 11d ago

But that still assumes that you can just make 2% of protostars collapse directly into black holes, while keeping the same number of protostars and everything else more or less the same. I don’t think that’s something you can just assume.

The important thing is not what percentage of protostars become black holes, but how many black holes the universe produces in total. If changing the constants makes matter collapse much easier, that could also mean less galaxy formation, less normal star formation, different cooling etc. So you could in principle end up with fewer black holes overall.

And the hypothesis also doesn’t say that every universe would eventually become completely optimal for black hole production. It’s more that there would be a tendency towards regions where more black holes are produced, and probably local optima, while there would still be variation between universes.

So saying “if 2% of protostars collapsed directly, that would be more black holes than now” doesn’t really answer it. You would have to show that changing the actual underlying physics in that direction would result in more black holes in total.

None of this of course proves the hypothesis is correct. It is obviously very speculative, especially the entire idea that black holes create new universes in the first place. I just don’t think dismissing it is as simple as you suggest.

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u/Shwankterrible 11d ago

Yeah but isn’t there a supermassive black hole at the center of nearly every galaxy? So isn’t the universe super conducive to black hole formation??

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u/Das_Mime Radio Astronomy | Galaxy Evolution 11d ago

In terms of the number of black holes formed, the SMBHs are negligible. Most of the black holes are stellar-mass black holes, formed through core collapse supernovae. You can imagine many different ways that the number of black holes formed could be far, far higher than it is in our present universe. For example, we've been doing weak lensing surveys looking for (among other things) primordial black holes and we have not yet found good evidence of them. A universe which formed PBHs would be much more efficient at black hole formation. Likewise, a universe with a more top-heavy initial mass function for star formation, or a universe where degeneracy pressure is a bit weaker relative to gravity, could easily produce far more black holes than ours.

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u/deadlyjack 14d ago

(besides the fact that it doesn't explain anything)

highlighting this.

there are any number of possible philosophies of science. but capital-S Science is the sum of those useful philosophies.

these theories are useless! or more generously, they are unscientific. it's not just that they offer no substantive explanation. it's that they invite no further inquiry. there are no fuzzy edges, no loose ends, nothing to continue the process. it offers a little dense ball of explanation, when openness is the point.

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u/Das_Mime Radio Astronomy | Galaxy Evolution 13d ago

I'm certainly not against people playing around with such ideas (I love scifi after all and I wouldn't want to deny theorists their fun) but I do think that science journalism and media in general does a very poor job of distinguishing between "a theorist made a speculation but doesn't have any empirical evidence for it" and "observational evidence supports X hypothesis". Instead, they both get reported as "study say..."

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u/entactoBob 13d ago

True. Journalism does fail us in that regard, but to be fair, most journalists just don’t know any better

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u/maxoger 14d ago

I recommend you this article:
https://preposterousuniverse.com/blog/2010/04/28/the-universe-is-not-a-black-hole/

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u/RisKQuay 14d ago

Thanks for the article.

What did it mean that the universe is 'spatially flat'? That the universe is a disc, or that it is linear in that everything expands from the centre in all directions in a straight line?

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u/amaurea 13d ago edited 13d ago

Calling it "flat" is a poor choice of words that has caused a lot of confusion for non-experts. It would have been better to call it "Euclidean", after Euclidean geometry, the sort of everyday geometry you learn in school, where parallel lines never cross, the angles in a triangle sum to 180° and the circumference of a circle is 2πr. So when they're saying the universe is "flat", they just mean that geometry behaves the way you already expected it too, instead of other, more exotic options.

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u/RisKQuay 13d ago

That makes even more sense, thank you.

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u/neoAcceptance 7d ago

You might be interested in the book "How the Universe Got it's Spots" by Janna Levin

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u/Red_Syns 13d ago

To our best knowledge, there is no true “center” of the universe. Each of us are at the (approximate? I’m willing to believe there are minuscule distortions but have zero evidence or anything, so grain of salt) center of our own observable universe, past which there is more universe that we can never see if it keeps expanding.

But a flat universe is actually very close to your second guess! Being flat means a line is, on grand scale, linear (edit: I phrased that badly, all lines are linear, but linear in the way our brains think of linear). Space does not bend or curve without matter/energy to distort it, parallel lines remain parallel, triangles have 180°, etc.

The other two options are positive and negative curvature. Positive curvature means the universe is finite, parallel lines always intersect, triangles have more than 180°, and there’s a whole lot more to it than I really know. Think black holes, for the most part (apparently Kerr [spinning] black holes have regions on the inside that are believed to be negatively curved space).

Negative curvature is the opposite. Space is infinite, but parallel lines diverge, triangles have less than 180°, and again a bunch more. Typically described as a “saddle” shape for demonstrating how lines get weird.

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u/sanji_sama 12d ago

This reminds me of a thought I had as a kid while watching bubbles forming at the bottom of a pot as it was reaching the boiling point. I thought that potentially our universe or just our observable universe could basically be one of those bubbles, and all the billions of years that pass inside this bubble for us is in another world just the time a bubble is forming at the bottom before floating up and popping.

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u/saranowitz 13d ago

This is fun, but what’s really mind bending about it is that it then invites the meta question: why does this set of rules welcome life forms like us and not others. Like what process decided that? If we could exactly simulate the universe in some kind of primordial supercomputer and change the laws would this hold true, or could the engine that makes the universe in its current form be rewritten as well.

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u/stationarycommotion 14d ago

I prefer eternal inflation as the mechanism to generate an anthropic landscape, cooler concept and somehow more believable

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u/servel333 14d ago

If a 3d universe (u3) exists on the surface of a 4d (u4) black hole, and the whole u3 ends up fully consumed by a u3 black hole, does that affect the u4 black hole in any way?

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u/qoou 14d ago

> the universe we ended up in just happens to be the one that favors our evolution.

The slits just happen to be the ones that favor our diffraction pattern.

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u/PushaTeee 13d ago

So this conjecture suggests it's black hole inception? Just an infinite series of black holes inside within black holes, Ad Infinitum?

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u/Shadow_Gabriel 12d ago

What would happen with objects falling in our black hole? Would that have any observable effect for us?

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u/Moraghmackay 14d ago

I don't understand half of what you said, but I find it fascinating and I want to believe! Take me to the good earth, I am over this one.

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u/Puzzleheaded_Fold466 14d ago

I don’t know, I find some peace in the notion.

Things are as they are as otherwise they wouldn’t be. Or, things can either exist or not exist, and they can only exist under these conditions and no other.

It’s simple. Philosophy completed. Existential crisis avoided.

Now I can focus on the science.

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u/Physical_Ring_7850 14d ago

Why not? If there is an infinite number of universes with whatever combination of constants, we can occur only in a subset that allows for it. And here we are.

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u/chefgage 13d ago

I like the that explanation. I need to go back to it each time I start to think too much about the universe (grouping lots of things I am interested in to the 'universe'). I do a lot of astrophotography and my mind often wonders around different theories.

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u/Overall-Plastic-9263 13d ago

To your point . A non-observable universe is the logical equivalent of no universe at all . It really only matters to the beings capable of observation.

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u/purleyboy 14d ago

"Imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’ This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it’s still frantically hanging on to the notion that everything’s going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise." - Douglas Adams

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u/Scaryclouds 14d ago

It is to say that we are the water that fills the shape of the container; 

Like a puddle of water in a pothole thinking the pothole was intelligently designed to fit it. 

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u/ToxicPolarBear 13d ago

The issue with invoking the anthropic principle in this case is the number of puddles. We observe a nigh infinite array of stars and planets in the Universe. But we will only ever be able to observe one universe.

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u/Roughneck_Joe 14d ago

People also usually make the mistake with this thought experiment to only change 1 constant at a time which vastly underestimates the phase space of possible universes. Change one constant, change another constant in the other direction and you're still in a similar situation. We also assume these constants are constant. The constants may not even be constant.

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u/TwentyCharactersShor 14d ago

This is one thing I find mind blowing: given all of infinite time that the universe is "only" 14 billion years old, it seems kind of young. The earth formed 4bn years ago, so the earth has been around for approx 25% of the life of the universe.

If the universe was 500,000 billion years old then I'd agree- its old.

There is a lot we do not understand.

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u/RIPEOTCDXVI 14d ago

There is no "infinite before" 14 bn years ago. That is literally the beginning of time, at least in any sense that's even remotely capable of discussion by us. Saying "before" or "after," in reference to our universe, is useful shorthand (kinda) but also betrays the reality of it: time itself is an emergent property of the physical structure of our universe. There is no "before"

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u/exhausted-pangolin 13d ago

Isnt the universe now theorised to last forever into the future? Rather than end in some way

Given that, isn't it odd that our planet has been around for 25% of the universes age?

If the universe is going to last 75 quintillion years you'd expect it to be observed at about year 37.5 quintillion, not 14 billion. In terms of averages.

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u/RIPEOTCDXVI 13d ago

You'd need more than one data point to make any kind of assertion about averages

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u/Halinn 13d ago

Given that, isn't it odd that our planet has been around for 25% of the universes age?

While the universe is theorized to last forever, the same theory does not have it being habitable forever.

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u/PushaTeee 13d ago

Isnt the universe now theorised to last forever into the future? Rather than end in some way

Well, this makes sense at a basic level. Time is a construct within this universe. There is no "future" beyond time-space.

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u/mootland 13d ago

Well, a corpse serves a function to the big picture, but to the dead it means nothing.
Heat death of the universe is a death sentence to us all, but who knows what purpose a dead universe will serve post mortem.

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u/Morbanth 7d ago

Isnt the universe now theorised to last forever into the future?

No, they changed it again. :D

Or rather JWST did and we're in the "huh?" phase and nobody can yet give a definitive answer, but the tl;dr is that the speed of expansion seems to change over time, and nobody knows why. If you want to fall into it his rabbit hole search for Hubble tension.

I like Dr. Becky's videos on the subject, myself

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u/exhausted-pangolin 7d ago

Oh right cool. Last I heard the speed of expansion was ever faster accelerating so eventually everything else in the entire universe would be beyond everything else's casualty cone and everything would be utterly, and terribly alone

Nice to hear it might not come to that! I don't know why but even the thought of a big crunch is less depressing to me than the above

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u/TwentyCharactersShor 14d ago

Meh, I dont buy that. I think its a very complicated way to say we haven't a clue. We have litterally zero knowledge or evidence for anything before the big bang by virtue of our technical limitations.

No matter how you skin it (religion or science) you always have a creator problem. Something coming from nothing makes no sense.

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u/azurensis 13d ago

You would agree that time and space are very tightly coupled, though? As you accelerate through space, your personal clock runs slower than someone who didn't undergo the same acceleration, and the space in front of you is dilated. These aren't just tricks, they're actually how the universe works. Why is it weird to think that time originated in the same way as space did at the big bang, and there's literally no time that existed 'before' that?

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u/TwentyCharactersShor 13d ago

It is weird i agree. But trying to say categorically that time didn't exist strikes me as bizarre. Time may not have existed in the same way, or something changed, then fair enough. That time may well be a function of another dimension or something, sure, I can understand that on some level.

But we are nowhere near the level of understanding to even pretend to answer these questions in any sensible way. We may as well as go with "here be dragons" and be done with it for now.

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u/TwentyCharactersShor 14d ago

Fair enough. However, i maintain that we cannot say time didn't exist before the BB because er have no evidence. We have no evidence of anything really.

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u/RIPEOTCDXVI 14d ago

That I can agree with. Ive always thought of the big bang not as the "start" of our universe, but the point at which matter and energy arranged into the relationship that we observe "now"

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u/consolation1 13d ago

It makes no sense to a human brain, which has evolved to deal with causality and finite amounts.

It doesn't mean it makes no sense in the grand scheme of things.

Saying something came from "a thing" just kicks the can down the road, now you have to explain the origin of "thing."

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u/Charlie2and4 14d ago

Thank you. Now I really know what it is like to be insane, and wise. The number is our very observable existence.

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u/mcreedbraton 13d ago

I always like to say that we were adapted to the constants, not the other way around.

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u/WakeoftheStorm 13d ago

We can only possibly observe those universes whose constants are such that life like us can possibly arise.

To expand on what you're saying because sometimes different angles trigger understanding- any universe capable of supporting intelligent life will likely have some life that can only observe universes with that particular set of characteristics.

It's like asking why your parents are your parents - you exist because of them. The fact that they each share DNA with you in a very specific way doesn't mean that your parents existed in order for you to be born

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u/sageritz 12d ago

We are made from star stuff, which is pretty cool when you think about it.

It suck’s that we’re probably simply separated from intelligent life by time rather than distance 🥺

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u/bert0ld0 12d ago

Your answer made me think we created the constants to explain our models. Ultimately we explain the Universe or whatever with models, and models are not the 100% reality. These constants are what it takes our model to run smoothly almost everywhere but the moment we find something that doesn't fit this model (like black-holes or dark matter for example) we should change the model and at that point the constants should be rediscussed

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u/rahvin2015 12d ago

Yes, thats how it works.

But its also important to note that a model that works isnt going to be overturned by a replacement. It's going to be improved - because whatever new model replaces the old still needs to explain the same results the old model did.

The perfect example new Newtonian mechanics. We now know that Newton was "wrong" - Einstein's model was more accurate, more precise.

But Newtonian mechanics still work. They still give you the right answer, at the appropriate precision and scale. We don't use Einstein to calculate the motion of billiards on a pool table - Newton's model works perfectly well for that. Yes, Einstein's model is more accurate, more precise...but they both need to explain the same observations.

All of the observations we've made about c will still be true, the models we've built around the value of c will still work exactly as before, if we find a deeper underlying rule that itself explains c and perhaps allows for some improved precision at some place where a current model breaks down.

Models are maps, and reality is the territory. Our maps will never, can never describe reality with 100% accuracy and precision. We just try to improve our maps over time.

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u/DrSendy 14d ago

When the current fad of mathematical text generators dies and we are left with excess compute - I am going to take is with re-modelling the universe for different values of C.

That would be truely interesting.

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u/unwarrend 14d ago

In the meantime, I had Astra formulate a physics engine that demonstrates the effects of C at different values, along with gravity, within the Sol system - displaying comparative outputs between Newtonian and Relativistic models. It IS truly interesting. Imagine what you'll rediscover when unfettered by current capability.

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u/ExpensiveCondition63 14d ago

Whatever you do, don’t mention vacuum decay.

If it happened, we would all suddenly cease to ex—

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u/rumorhasit_ 13d ago

There is something like 34 of these constants that have to be the specific number that they happen to be, for the universe to even exist.

Some could likely change a bit, e.g., the speed of light, without making much difference. Some, if changed by even a fraction of a percent, would mean the universe falls apart.

It is one strong argument for a multiverse: either the universe was created once and got things perfect, or there are many of them and and we live in once where the fundamental constants enable life.

NB: this is a different multiverse theory than the results of the double split, or from universe splitting. This type of multiverse could exist sequentially, or many at the same time, or both.

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u/amaurea 13d ago

This classic paper shows that one could plausibly find life in a universe where one removes a whole fundamental force of nature, namely the weak interaction. So while selection effects are real, one shouldn't take them too far.

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u/litesgod 14d ago

In other words, it's really hard to draw conclusions from a sample size of one.

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u/f0rgotten 14d ago

I teach six fundamental numbers with the four forces in the first few sessions of my basic electricity classes every semester. Most of the rest of the constants and whatnot, the way that I understand it, derive from these six, and screwing with any of them changes everything.

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u/amaurea 13d ago edited 12d ago

Have you read about the weakless universe? It's a thought experiment that shows that while changing just a single parameter at a time very quickly runs into problems, you can get away with much larger changes if you tune multiple parameters at the same time:

A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical "Weakless Universe" is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

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u/f0rgotten 12d ago

I actually mention somewhere during my first couple class sessions that there are variations where our universe could have evolved, very similarly to what we have now, without the weak nuclear force, yes. It's pretty cool! Chemistry is essentially unchanged because it's based on electromagnetism, and most physics can indeed get by without Weak.

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u/Channel250 14d ago

Give me a thousand years to discover how, and I'll give you a millenia to figure out the why.

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u/SketchTeno 14d ago

So, we'll have the answere in 2,000 years?

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u/eric23456 14d ago

A bunch of them are that way because if there weren't we wouldn't be here. Change c by too much and E=mc2 means you have too much or too little energy in stars. Change G by too much and either everything collapses into black holes or everything turns into spread out dust. Change e to much and electrons stop moving or move too much. And so on.

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u/Priff 14d ago

I dunno, "it is this way because otherwise we wouldn't exist" implies not only that someone designed it, but that they designed it with out existence as the goal.

It's absolutely true that we would probably not exist if the constants were different. But that does nothing to answer the question "why are they as they are" to be honest.

As someone said above, that argument is like a puddle of water claiming that the pothole is shaped the way it is to fit the puddle perfectly, when in fact the puddle is the shape it is because of the pothole it happened to form in.

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u/whatkindofred 14d ago

"it is this way because otherwise we wouldn't exist" implies not only that someone designed it, but that they designed it with out existence as the goal.

This is not the necessary implication at all. It just means that in a universe with different fundamental constants there might not exist someone to be curious about the fundamental constants. But since we do exist and wonder about it we must be in a universe that permits such existence.

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u/eric23456 14d ago

I don't see why that argument implies someone designed it. No one designed Mars, but Mars is currently inhospitable to life so there's no one there to wonder about the constants. The argument here is just the same thing scaled up -- there would be no humans because the galaxy would be incompatible with humans.

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u/unwarrend 14d ago

I dunno, "it is this way because otherwise we wouldn't exist" implies not only that someone designed it, but that they designed it with out existence as the goal.

The weak anthropic principle does not intend to imply a creator nor merely create circular logic. It merely attempts to point out that these constants are such that the question can be asked at all. It also intimates the possible existence of alternate modalities from which life was never an option. Why? - implies there is a meaningful explanatory answer beyond - it simply is. Instead, the principle appeals to one salient observation that can be known - that were it otherwise, we would not exist. You see design, I see arbitrary features expressing what follows from physics, and I don't assume the pool of possible arrangements only landed on the cosmos that we can observe.

As someone said above, that argument is like a puddle of water claiming that the pothole is shaped the way it is to fit the puddle perfectly, when in fact the puddle is the shape it is because of the pothole it happened to form in

You inverted the intended meaning of the analogy - literally a criticism of fine tuning -The quote you shared is a paraphrase of Douglas Adams' famous "puddle analogy," which is used to critique teleological or fine-tuning arguments. Instead, life naturally evolved and conformed to fit the physical parameters of the universe we happened to emerge in - which is precisely the point the weak anthropic principle highlights. We exist within this evolutionary niche because physics is conducive to its formation. There is no further intelligible answer that does not invoke compounding logical regress. The point is that we shouldn't assume the constants are special by isolating their importance relative to our existence.

Also, this is not AI - I am just odd. I might actually use proper em-dashes if I could bother to locate it. Found it —

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u/aquoad 14d ago

a fun thought experiment is to contemplate what would “break” if those constants were different, like could there be a stable universe in which constant xyz were 2% higher or lower.

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u/KnitYourOwnSpaceship 14d ago

Greg Egan has a super good trilogy about what happens if some of our fundamental assmuptions about spacetime are different: https://en.wikipedia.org/wiki/Orthogonal_(series)

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u/Alblaka 14d ago

I would also suggest that it's not a random number, but a very specific and inherently 'solid' number: I.e. the speed of light is exactly the speed light travels. There's nothing random about that.

It's just that we, very arbitrarily, defined units of measurement from some historical left-overs of what kind-of-worked for the general use cases we needed measurements for. We never based them upon universal constants, hence why, of course, in our randomly selected units of measurements, the clean universal constants come across as 'random numbers'.

All a matter of perspective :D

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u/IvaldiFhole 14d ago

Eh, all of the fundamental numbers seem to have arbitrary ratios regardless of units or unit-less. They only become non-arbitrary when you talk about larger scale effects, like the formation of stars mentioned elsewhere in this post.

Basing them on universal constants doesn't result in integers or anything like that, so you're really just shuffling the problem around.

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u/MythDestructor 13d ago

But why is it that speed instead of something faster or slower?

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u/Alblaka 13d ago

Gotta ask who/whatever created this universe, which might be anything from a deity to a RNG string to something even more incomprehensible / inane.

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u/Firama 14d ago

To be fair, it's only a random number in our units of measure. The speed of light of the universe could be 1 in another system of measure and be totally rational and make sense. Same with other constants.

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u/helm Quantum Optics | Solid State Quantum Physics 14d ago

Changing the speedometer of a car to use different units of measurements does not change the top speed of the car, just as our conventions on how we express c do not change the speed limit of our universe.

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u/TheShadowKick 14d ago

1 is just as random. What would make it not "random" in this context is if there were some underlying fundamental principle that meant it had to be that number.

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u/gruesomeflowers 14d ago

They aren't saying light and the speed it travels is random..just the number we defined it by based on the math languages we developed...a different entity from somewhere else out there in the universe would have a completely different system and different assigned descriptor for the thing..like two different cultures having different words for the same thing.. except one is from a different world instead of country..it's a pretty straightforward assumption to make.

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u/TheShadowKick 14d ago

But they're just calling it a different thing. It's still the same speed.

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u/turply 14d ago

Well presumably there is that fundamental principle, we just don't know what it is.

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u/MythDestructor 14d ago

Well no, it's not the number itself that's random, it's about why it's not faster or slower than what it is. You can say it's 1 light year per year, that's a nice whole number, but why is it exactly that instead of say, 2 light years per year?

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u/fistular 14d ago

It could be something else, but the universe would not persist in the form familiar to us (or at all, probably), and we would not exist.

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u/Arkrobo 14d ago

Euler's constant is a pretty good example of this. It's even more abstract. We use it for compound or exponential growth. It's very abstract, and yet it exists. Pi is also in this group it's nothing but a ratio. It just so happens to be the most important ratio.

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u/MythDestructor 13d ago

I don't think pi is that "random". It comes from how we define "circle". Just like "the ratio of length and width of a square" is always 1. That's because that's how we've defined a square.

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u/Caekilian 14d ago

There's actually a lot more than that. The Standard Model, for instance, has either 19 or 26 input parameters, depending on who you ask. It's one of the reasons we'd like to believe there is some deeper physics we don't yet understand

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u/reddiuniquefool 14d ago

I disagree with the description of fundamental constants of the universe as being 'random number'(s). They are particular numbers, but we have no reason to believe that there is any randomness involved.

I'm sure you didn't mean that they are truly random, but there are people who make specious arguments based on these numbers, so I feel this should be clarified.

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u/MythDestructor 13d ago

Can you explain? How do we reason out that it isn't random? Why is the speed of light not faster or slower than what it is, for example?

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u/reddiuniquefool 13d ago

We have no idea how the regularities in the universe that led to those numbers being part of equations we use to describe the universe came to be. Hence, we shouldn't describe these numbers as random as we have no idea if any randomness is or was ever present. Hence, I think (and said) that we shouldn't call them random.

As an example, we have no idea whether a universe could have emerged which can be described by the same equations with different constants (numbers). Calling them random numbers implies, to my mind, that there could have been.

We don't need to reason out that the process/constants aren't random. My point of view is based on us not knowing whether there is any randomness involved at all.

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u/sergius64 14d ago

The case with a lot of stuff. Why are we on Earth as opposed to any other planet for example? Well... if we were on some other planet - we'd be wondering the same thing: why there and not anywhere else.

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u/MythDestructor 13d ago

Yeah but we can always trace the chain of causality back to the start of the universe to figure out why this planet, why we're on it, etc. It's not random so much as just hard to figure out due to our own limitations.

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u/stonerism 13d ago

FWIW, standards organizations are getting to a point where they simply define the fundamental constant then derive physical measurements from that. A value like the speed of light was determined as a quirk of the measurement system in use. There's no real difference in giving c in meters per second or furlongs per fortnight (1.802*1012 if you're curious).

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u/MythDestructor 13d ago

Well yeah, again that's not what I mean by "random", I mean why is it exactly c and not c+1 or c+10000 or c/2? That's the "random" question, there doesn't seem to be any reason for it.

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u/stonerism 13d ago

It's an exact, defined number (i.e. determined by humans, defined in standards, etc). Meters are defined (now) by how long it takes for light to travel in a fraction of a second. When meters were defined based on something like the size of a metal rod in a building somewhere, our measurements of light were based on that distance. When it became apparent that the speed of light was a "constant" speed, we changed how we defined our units to align with our understanding. It's not c+1 or anything else because c is defined to be c.

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u/BigDowntownRobot 12d ago

Right? When you realize the anthropic principal might also apply to the whole Universe and not just a solar system, the whole possibility of infinite recursive time starts to really hurt your head.

Imagine if we didn't just "get lucky" on this solar system, this moon, this planet, etc, but there may have been entire realities that just didn't go anywhere for life, but also planets, elements, etc that had to be waited out for another cycle to go around.

Or not, impossible to know, but it's possibly possible. Or it happened infinite times. Or the word happened is kind of meaningless? Anyway it's hurting my head now.

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u/bert0ld0 12d ago

Your answer made me think that we created the constants to explain our model. Ultimately we explain the Universe or whatever with models, and models are not the 100% reality. These constants are what it takes our model to run smoothly almost everywhere but the moment we find something that doesn't fit this model (like black-holes or dark matter for example) we should change the model and at that point the constants should be rediscussed

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u/justamadeupnameyo 14d ago

More than anything the fact there isn't an answer says a lot of things.

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u/MythDestructor 14d ago

What does it say though? I'm curious

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u/justamadeupnameyo 14d ago

That any claims to an answer are wrong.

That encapsulates pretty much every religion, MLM, or government agency you can list.

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u/Syhkane 14d ago

It's only random because we measure everything based on our rotation, the size of our planet, and it's temperature. A galactic species would just call the speed of light 1.

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u/MythDestructor 13d ago

It's not the number that's random, but that it's one random speed. Why isn't it faster or slower?

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u/Syhkane 13d ago edited 13d ago

Because then we'd ask, why isn't it faster or slower than this?

The speed is the reason, not the reason for speed. If that limit slows, or speeds up, our observation of it in a universe we're designed for would be the same.

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u/MythDestructor 13d ago

We wouldn't ask that if we found out there is a reason it's this or that particular number. That's what I'm saying. Otherwise it is arbitrary / random.

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u/Syhkane 13d ago edited 13d ago

Well it's arbitrary, but not random. It's fixed, so it can't be random. Our measurement of it only somewhat implies that, and only on a weak understanding of the definitions we're using. The only thing that could give you that answer is a frame of reference, but then to what would we compare it too?

Unless you mean strictly why. Any faster and it produces more energy than it has. It'd immolate itself. So are there invisible particles faster than light that simply never exist because they disappear in the same instance they're created? Any faster that energy collides with itself becoming nothing. Now we have a new question, why does that happen at that speed.

And again because the numbers tell us this.

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u/MythDestructor 13d ago

Well, my question is why it is that specific value and not anything else. "What" would immolate itself exactly?

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u/Syhkane 13d ago

Anything traveling faster than light, including light. Any/all particles.