Does Planck length and irrational solutions mean time can't be reversed?

In summary: It proposes that space and time are made up of discrete, indivisible units called "atoms of space" or "quanta of space-time." This is similar to how particles are quantized in quantum mechanics. However, this theory is still being researched and is not yet widely accepted.In summary, the conversation discusses the concept of quantizing space and time, with a focus on the Planck length as a unit of measurement. The speaker suggests that quantizing space-time would break rotational and Lorentz invariance, but also mentions the theory of loop quantum gravity which proposes that space and time are made up of discrete units.
  • #1
TylerH
729
0
If there is an irrational solution to an equation for where a particle should be, for example from an ODE, then what effect does Planck length have on that? Does the actual position of the particle get rounded to an a multiple of the Planck length? If it does, wouldn't that imply there is a loss of information as time flows forward, making it impossible to go back?

Thanks for your time,
Tyler
 
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  • #2
The plank length is just a unit to measure distance with (although it is nice in the fact that in plank units G=c=h=1), any irrational solution could easily be made to be rational by picking units that make it rational so irrationality doesn't really matter. Why would things have to round up to a multiple of the plank length?
No standard theories quantise distance.

I could be misinterpriting what you're trying to ask here however
 
  • #3
No, you seem to be interpreting what I said correctly. I assumed that since between Planck length, two points are indistinguishable, then space is quantized.
 
  • #4
Thanks for the explanation. I need to really learn physics before I try to disprove time travel, apparently. :)
 
  • #5
No problem buddy :D
If theories were to quantize space then the plank units would be the perfect candidate to quantize it as (but then results derived from these theories would have explicitly quantised results so you wouldn't bump into the problems you described). There's also been thoughs about the plank length being lorentz invariant and I believe that loop quantum gravity quantizes area in units of plank length squared, but I really know very little about these theories.

In terms of the results of your standard run of the mill quantum mechanics, as it is now, there is no quantization of time or space
 
  • #6
I'm not that well educated on the standard theories of higher physics. I know there are ODEs for the relation between the change in time and some function of gravity and speed; with gravity itself really being a function of position and time, and speed being a function of time. Which I think are from Einstein's theory of relativity...

What I was thinking is that maybe spacetime was actually quantized itself, as in it actually rounded somehow to quantize to the Planck length. (Even subatomic particles would be centered around an integral of the grid. I just found out this is called a lattice gauge theory, I think.) I tend to think like a computer scientist, since that is my favorite area of study. Hence my tendency towards a quantized and finitely computable theory of the universe.
 
  • #7
I can't think of any way of quantizing space-time without breaking the concept of rotational invariance and Lorentz invariance. If we assume each grid cell has the same shape, it seems to me that the grid cell needs to be some 4d variant of cubic or hexagonal closest packing. Hexagonal grid cells would limit you to rotation by 60 degrees, which totally diagrees with measurement.
 
  • #8
Loop quantum gravity, one of the major hypotheses for unifying general relativity and quantum mechanics, quantizes space-time.
 

1. What is Planck length and how does it relate to time reversal?

Planck length is a unit of length that represents the smallest measurable length in the universe. It is derived from fundamental constants such as the speed of light, gravitational constant, and Planck's constant. The concept of time reversal refers to the idea that if we reverse the direction of time, the laws of physics will still hold true. However, at the Planck length, this concept breaks down, and it is believed that time reversal may not be possible at this scale.

2. How does irrational solutions affect the concept of time reversal?

Irrational solutions refer to solutions in physics equations that cannot be expressed as a ratio of two integers. These solutions have been observed in the study of quantum mechanics and may play a role in the concept of time reversal. Some theories suggest that irrational solutions can lead to time asymmetry, meaning that time reversal may not be possible in certain scenarios.

3. Can time ever be reversed at the Planck length?

At this time, it is not definitively known if time can be reversed at the Planck length. Some theories suggest that time reversal may not be possible at this scale due to the breakdown of the laws of physics. However, more research and experimentation are needed to fully understand the concept of time at the Planck length.

4. How does the concept of entropy relate to time reversal at the Planck length?

Entropy is a measure of the disorder or randomness in a system. It is closely related to the concept of time, as time is often seen as the direction in which entropy increases. At the Planck length, the laws of physics that govern entropy may break down, which could affect the possibility of time reversal at this scale.

5. What are the implications of time reversal not being possible at the Planck length?

If it is proven that time cannot be reversed at the Planck length, it could have significant implications for our understanding of the universe. It could challenge the concept of causality, which is the idea that events are caused by previous events, and could also impact our understanding of the origins of the universe. However, more research is needed to fully understand the implications of this concept.

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