Just completed a planck marathon. With that said... I’m worried I have an injury coming on from over training :(
I was going to post this to /r/askscience but I decided it's more of a philosophical question. But the basic premise is that the Planck length (in chemistry) is considered to be the smallest possible length in all of the universe. Could we not consider the accuracy of this value (1.616255(18)×10−35 m)1 to be the needed precision to calculate an "exact" definition of pi, given that the MOST ACCURATELY DRAWN CIRCLE could only ever exist down to this level of precision? Where is the difference between mathematically provable (pi is irrational) and what actually exists in reality? Because by this definition, what we think of as a circle can't actually exist in the physical world, but somehow it can exist in your mind. Or can it?
Thanks for listening! Newcomer here, hope this fits the vibe.
1 The two digits enclosed by parentheses are the estimated standard error associated with the reported numerical value
https://en.wikipedia.org/wiki/Planck_length#:~:text=In%20physics%2C%20the%20Planck%20length,developed%20by%20physicist%20Max%20Planck.
Edit: I really really appreciate all the thought people have put into their responses. I will take time reading through over the week and trying to respond where I can!
I'm intentionally not using real units so bear with me conceptually for a moment. If a planck length is traveled by applying some force what happens if you apply less force than that and a planck length is the smallest unit of distance something can move is space is quantized? What happens to the extra energy if the object does not move? Where does the force go, absorbed by the fabric of space as you push against it but dont move? What happens if you apply 1.5 units of force, still no movement? What about 1.999 units of force (where 2 units moves 1 planck length) would it still not move or if you get close enough to the energy needed to move it one planck length will it jump that distance and if so where does the extra energy come from?
I may not be using force energy etc appropriately here but I'm hoping you understand my fundamental question of if there is a minimum distance scale what happens if you apply energy to move over a smaller distance scale?
"There's quite a few of us in this universe... We should try to be discrete."
I'm not really into physics and what not, I just know the bare minimum. I'm a law student, so please believe I'm like 5 when it comes to this discipline of education.
Why is the Planck Length the "smallest thing in the world?" Or at least I hope I asked it right.
I've read that you cannot go smaller than this length, otherwise blackholes will occur and the world doesn't make sense anymore.
Could you explain the main steps to understanding "length" and it's relationship to energy before diving into the planks length? This concept is super interesting and I really want to understand it. From what I have read, understanding this concept is broken down like this:
(1) What is a wavelength actually?
(2) How are wavelengths and energy related?
(3) Why is the Plancks Length the smallest thing in the universe?
(4) What happens when something is smaller than a Planck Length?
Thanks!
For context, I have an advanced degree in mathematics but not much physics knowledge. I've been reading about how it is an unsolved question whether spacetime is fundamentally continuous or discrete. The fact that there is apparently a smallest possible unit of distance, to my limited understanding, would imply that spacetime is discrete, with Planck length acting as the "pixel" of the universe, so to speak. But I know it's not that simple, so what am I missing?
Edit: Ok, thank you. I saw a lot of non-wikipedia sources online that referred to Planck length as "the smallest possible size of anything in the universe" or "the smallest unit of length" but it seems that is not actually true. Should have noticed that the wikipedia article doesn't ever actually say that.
Posting here after this question was (for some reason I can't work out) deemed unacceptable to the mods of /r/AskScience
Disclaimer: I am in no way scientifically minded (History major...) so I'm sorry if I'm being ignorant/have a massive misconception in advance.
I'm familiar (from a layman's point of view) with the concept of a Planck length and a Planck time being the quantum of distance and time respectively, with measurements smaller than those being meaningless.
This kinda led me to think that light must have to functionally and instantaneously teleport the distance of a Planck length since there would a) be no way to meaningfully measure the time it takes light to travel half a Planck length and b) half a Planck length itself cannot for the same reason meaningfully be measured (as my chimp brain understands it).
In this scenario there would be no way to ever place an electron at the midway point, it would appear to teleport from the beginning to the end instantly (I think). Is this accurate? Am I secretly a genius (nop)? Or just a jumped up history frog who has no idea what they're talking about (YEP).
If I move sufficiently close to the speed of light relative to another observer, in one dimension I will be shorter than the Planck length. At that scale, quantum gravity should kick in and we don't know the rules. But should I and the other observer still be able to perform all experiments and get the same results?
Hello all, there's an aspect in regards to Cosmic Inflation that I keep trying to wrap my head around and was hopeing somebody smarter than myself can help me out with. How can you measure expansion if the reference frame itself is expanding? What is the ultimate reference, and why? ... What do I mean, I understand the ideea that space itself is expanding in all directions but I'm wondering if there could be a another 2 ways of seeing it:
1)If we observe (just as an example) two points in space that are exactly 1 light year apart , and then, after a long period of time, we observe the same two points are a little more than 1 light apart, a.k.a. it take light a little more than one year to traverse the distance, we could say that of course space is expanding...or, can we say that light is slowing down? (This is a purely theoretical example, regardless of speed of expansion or how to practically measure it). I know we consider the speed of light to be constant, but it's constant to what reference frame, an expanding reference frame ?
2)If we measure the distance between 2 points as a finite number of Planck lengths, the smallest unit of measurement , and over time, we see that between the same 2 points there are now more Planck lengths between them, we can conclude that the universe is expanding , but can we conclude that maybe the Planck length is getting shorter? In other words, what would be the difference, from a observational point of view, between an expanding universe, and a continuous "subdividing universe"?
The 2 examples are just "what ifs", not saying that this is the case. The General question would be, how can you really measure anything when everything is relative to everything else? ... And I don't think "the speed of light is constant, ...cause we say it is...and so we measure everything in relation to that" is really a good answer.
Can a slowing down of light speed or shortening of the Planck length produce the exact same observations as an expanding universe?
Sorry for the long post, If you could help me out with an informed option or related articles on this topic of relative reference frames that would be very much appreciated. Thank you. :)
EDIT: Please do not take too literally previous examples. I really regret the "light constant cause we say so" part. The real question, as formulated way better in a comment is: Is there an alternative, mathematically sound, model of the universe, where we consider distances fixed, and speed o
... keep reading on reddit ➡I don’t know how to describe this clearly but ..
Does this mean that time is running a planck’s time after a planck’s time?
To clarify, initially we'd start with a A4 paper 21x30cm (I rounded the 29,7cm to 30) with 0.1mm of thickness.
Then we'd have 21x15 > 10,5x15 > 10,5x7,5 > 5,25x7,5 ...
(Folding on the vertical axis then on the horizontal axis and following that pattern)
So how tall would it get if one side of the paper was 1,6 x 10^-35?
Pretty stupid question, but if any mathematicians are bored and want to try this out I'd appreciate.
Edit: A speeding object that is one Planck length still contracts in length for an outside observer by the Lorentz transform, right?
In the kurzgesagt Universe scale App it’s defined as “The Planck length is the distance light travels in single unit of Planck time. A unit of Planck time is defined as the time it takes for light to travel one Planck length. A bit of circular logic by Planck”. So essential what I’m asking is where does this “circular logic” derive from?
Why would universe have "pixels"? And why do physics stop working on the smaller sizes?
Think of the universe as the side of a piece of glass, and Planck Length as a tiny hole. Do you think that if we could reach further than Planck Length than we could travel to a universe parallel to our own (ie the other side of the glass)?
If the Planck length is the smallest length possible, is it possible to have 1.5 times the Planck length, or can you only add the Planck length.
