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The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers.

The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers. I cannot imagine anything being infinite in the physical world. I find the simulation hypothesis more probable than Universe being infinite. Space and Time is not infinite. It may be Gazillions of centuries old, but not infinity. It can't be.

jstanley 4y ago
If you're happy for mathematical structures to be infinite, why can't our universe (including ourselves) just be one infinite mathematical structure? Yes, it's very complex, but there's plenty of room in infinity. It doesn't need to have a "real" physical instantiation anywhere. It's like the simulation hypothesis, except you don't need the simulation. We're just the inside of an infinite self-experiencing mathematical structure, with nothing on the outside.
- defrost 4y ago
  It's an assumption that someone is happy with mathematical structures being infinite. There are mathematicians unhappy with the notion even while being well versed in the Cantor (and other) arguments. You can wander down that rabbit hole via (say) [1] as a starting point. [1] https://en.wikipedia.org/wiki/Constructivism_(philosophy_of_mathematics) https://en.wikipedia.org/wiki/Constructivism_(philosophy_of_...
- GoblinSlayer 4y ago
  Because universe is a physical structure, not mathematical, e.g. you can't define things into existence.
  - jbotz 4y ago
    Is it? Says who? This is an untirely unfalsifiable assumption. I personally don't share it. "It from bit"[0], I say, mathematics is fundamental, physical reality is just our perception of the underlying math. [0] Title of a paper by John Wheeler. Can't find it right now, but if you google "it from bit" you'll find a lot of commentary on it.
    - GoblinSlayer 4y ago
      The concept of fundamentality doesn't exist in mathematics, and it's by design. What is fundamental, Tailor series or Fourier transform? Mathematics doesn't care, it simply has no such concept.
    - GoblinSlayer 4y ago
      Found commentary on "it from bit". It looks like an attempt to resurrect antirealism (participatory universe). The reason why antirealism was buried is because there's too much realism in quantum physics, so it won't fly.
  - jstanley 4y ago
    This is exactly the position I'm trying to argue against. What does it mean for something to be a physical structure? That you perceive it to be physical? But aren't your perceptions part of the universe? So how would you know if it actually "exists" anywhere?
    - GoblinSlayer 4y ago
      Physical structure works by its own rules, mathematical structures work by our rules. For example, in mathematics you can complete an infinite process, because there's no time in mathematics, it can just be assumed out of existence. It can't be done with physics, because physics isn't affected by our assumptions.
      - jstanley 4y ago
        Time and physics are just things you experience. They're parts of the universe, they're within the universe. The mathematical universe itself can quite easily be infinite in both space and time, you just can't experience all of it.
- CuriouslyC 4y ago
  Physical systems have finite information storage capacity. Our infinities are descriptions of recursive processes (either iteration or subdivision). The quantization we've observed in the universe is a strike against infinities of subdivision, and it's literally impossible to observe a macro-infinity, so from a scientific perspective physical infinity is unsupported and seems unlikely. Space might appear "infinite" if you set up a word problem where you fire two photons off in opposite directions and track the distance between them over time, but without an observer the only place information exists is in those photons, and space is meaningless. Infinities of time are likewise artificial constructs of measurement, there is only the current moment.
chimprich 4y ago
The universe being finite in any way is even harder to grasp for me. How can existence itself have a beginning?
- sidcool 4y ago
  That's a great point. I don't know (obviously). But I tend to think that there is actually a point in space beyond which it does not make sense to ask the question "What is beyond this". Just like when we are at North Pole, the question "Which way is North" does not make sense.
threeseed 4y ago
Based on his talks Penrose doesn't either. It's just that we are talking about googolplex timescales.
schiffern 4y ago
>infinity seems impossible to me "Me," in this case, is a microcontroller that evolved to move muscles on a primate body effectively. Do we have any reason to believe such a system should be capable of grasping the true nature of the universe? After all, it's far outside the design spec!
- imbnwa 4y ago
  >"Me," in this case, is a microcontroller that evolved to move muscles on a primate body effectively. Distinction between brain and body not really a thing though, yeah?
user8501 4y ago
But it can’t NOT be infinite! If space were three dimensionally finite, then there must be a boundary. But if there were a boundary, then there must be something beyond that boundary. And now we have a paradox that infinitely regresses. Same goes for time. Same goes for distance. How can there be both a finite distance, as well as an infinite number of points between two distinct points? To me, infinity seems to be everywhere I look
- deleted 4y ago
  [deleted]
- kaashif 4y ago
  > If space were three dimensionally finite, then there must be a boundary. Not true, space might just repeat in all directions - a finite volume but with no boundaries. Maybe if you go far enough you always end up back where you came from.
  - user8501 4y ago
    That may be true. But if that we’re the case, then a fourth spatial must exist for the entire 3rd dimension to wrap in on itself. And then we find ourselves in the same infinite regression, wondering about the boundaries of the parent dimension.
- rramadass 4y ago
  https://news.ycombinator.com/item?id=35524131 https://news.ycombinator.com/item?id=35524131
twangist 4y ago
That seems to be a personal problem. There's nothing inconsistent about either space or time being infinite.
- sidcool 4y ago
  It's a personal outlook, not a problem. It's not a statement of fact. It's an opinion at best.
wafer_thin 4y ago
I can't think about these things too hard... stresses me out. What's a quark made up of again? 'Tiny rubber bands' :)
rramadass 4y ago
All "Infinities" are not the same, you are using the word in a colloquial sense (i.e. non-converging) while there actually are different definitions/interpretations. See wikipedia : https://en.wikipedia.org/wiki/Infinity https://en.wikipedia.org/wiki/Infinity "Cosmology" section; the key point being The question of being infinite is logically separate from the question of having boundaries.

jstanley 4y ago

If you're happy for mathematical structures to be infinite, why can't our universe (including ourselves) just be one infinite mathematical structure? Yes, it's very complex, but there's plenty of room in infinity. It doesn't need to have a "real" physical instantiation anywhere. It's like the simulation hypothesis, except you don't need the simulation. We're just the inside of an infinite self-experiencing mathematical structure, with nothing on the outside.

defrost 4y ago
It's an assumption that someone is happy with mathematical structures being infinite. There are mathematicians unhappy with the notion even while being well versed in the Cantor (and other) arguments. You can wander down that rabbit hole via (say) [1] as a starting point. [1] https://en.wikipedia.org/wiki/Constructivism_(philosophy_of_mathematics) https://en.wikipedia.org/wiki/Constructivism_(philosophy_of_...
GoblinSlayer 4y ago
Because universe is a physical structure, not mathematical, e.g. you can't define things into existence.
- jbotz 4y ago
  Is it? Says who? This is an untirely unfalsifiable assumption. I personally don't share it. "It from bit"[0], I say, mathematics is fundamental, physical reality is just our perception of the underlying math. [0] Title of a paper by John Wheeler. Can't find it right now, but if you google "it from bit" you'll find a lot of commentary on it.
  - GoblinSlayer 4y ago
    The concept of fundamentality doesn't exist in mathematics, and it's by design. What is fundamental, Tailor series or Fourier transform? Mathematics doesn't care, it simply has no such concept.
  - GoblinSlayer 4y ago
    Found commentary on "it from bit". It looks like an attempt to resurrect antirealism (participatory universe). The reason why antirealism was buried is because there's too much realism in quantum physics, so it won't fly.
- jstanley 4y ago
  This is exactly the position I'm trying to argue against. What does it mean for something to be a physical structure? That you perceive it to be physical? But aren't your perceptions part of the universe? So how would you know if it actually "exists" anywhere?
  - GoblinSlayer 4y ago
    Physical structure works by its own rules, mathematical structures work by our rules. For example, in mathematics you can complete an infinite process, because there's no time in mathematics, it can just be assumed out of existence. It can't be done with physics, because physics isn't affected by our assumptions.
    - jstanley 4y ago
      Time and physics are just things you experience. They're parts of the universe, they're within the universe. The mathematical universe itself can quite easily be infinite in both space and time, you just can't experience all of it.
CuriouslyC 4y ago
Physical systems have finite information storage capacity. Our infinities are descriptions of recursive processes (either iteration or subdivision). The quantization we've observed in the universe is a strike against infinities of subdivision, and it's literally impossible to observe a macro-infinity, so from a scientific perspective physical infinity is unsupported and seems unlikely. Space might appear "infinite" if you set up a word problem where you fire two photons off in opposite directions and track the distance between them over time, but without an observer the only place information exists is in those photons, and space is meaningless. Infinities of time are likewise artificial constructs of measurement, there is only the current moment.

chimprich 4y ago

The universe being finite in any way is even harder to grasp for me. How can existence itself have a beginning?

sidcool 4y ago
That's a great point. I don't know (obviously). But I tend to think that there is actually a point in space beyond which it does not make sense to ask the question "What is beyond this". Just like when we are at North Pole, the question "Which way is North" does not make sense.

threeseed 4y ago

Based on his talks Penrose doesn't either. It's just that we are talking about googolplex timescales.

schiffern 4y ago

>infinity seems impossible to me "Me," in this case, is a microcontroller that evolved to move muscles on a primate body effectively. Do we have any reason to believe such a system should be capable of grasping the true nature of the universe? After all, it's far outside the design spec!

imbnwa 4y ago
>"Me," in this case, is a microcontroller that evolved to move muscles on a primate body effectively. Distinction between brain and body not really a thing though, yeah?

user8501 4y ago

But it can’t NOT be infinite! If space were three dimensionally finite, then there must be a boundary. But if there were a boundary, then there must be something beyond that boundary. And now we have a paradox that infinitely regresses. Same goes for time. Same goes for distance. How can there be both a finite distance, as well as an infinite number of points between two distinct points? To me, infinity seems to be everywhere I look

deleted 4y ago
[deleted]
kaashif 4y ago
> If space were three dimensionally finite, then there must be a boundary. Not true, space might just repeat in all directions - a finite volume but with no boundaries. Maybe if you go far enough you always end up back where you came from.
- user8501 4y ago
  That may be true. But if that we’re the case, then a fourth spatial must exist for the entire 3rd dimension to wrap in on itself. And then we find ourselves in the same infinite regression, wondering about the boundaries of the parent dimension.
rramadass 4y ago
https://news.ycombinator.com/item?id=35524131 https://news.ycombinator.com/item?id=35524131

twangist 4y ago

That seems to be a personal problem. There's nothing inconsistent about either space or time being infinite.

sidcool 4y ago
It's a personal outlook, not a problem. It's not a statement of fact. It's an opinion at best.

wafer_thin 4y ago

I can't think about these things too hard... stresses me out. What's a quark made up of again? 'Tiny rubber bands' :)

rramadass 4y ago

All "Infinities" are not the same, you are using the word in a colloquial sense (i.e. non-converging) while there actually are different definitions/interpretations. See wikipedia : https://en.wikipedia.org/wiki/Infinity https://en.wikipedia.org/wiki/Infinity "Cosmology" section; the key point being The question of being infinite is logically separate from the question of having boundaries.