Question about planck lengths/quantized space and expanding space?

In summary, the length of a string in String Theory is comparable to the length of a circle with a circumference of Planck length, but the diameter of the circle is smaller than the Planck length.
  • #1
jeebs
325
4
If I'm not mistaken, it is thought that space is divided up into quantized little indivisible chunks, the size of which is called the Planck length.

Also, the space of the universe is thought to be expanding. We could have 2 objects stationary relative to one another at some time t_0, then allow space to expand from t_0 to t_max, and these 2 objects would then be at a greater separation.

Does this mean that each little block of space is itself stretching out (ie. the 2 objects have the same number of blocks between them at t_0 and at t_max)?

Or, is it that they stay the same size, but more blocks exist between the 2 objects at t_max than there were originally at t_0?
 
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  • #4
That's right, the Planck length is simply an order-of-magnitude length scale √(ħG/c3) at which both gravitational and quantum effects become dominant. There is so far no successful theory of what happens at that scale. Presumably the simple concept of continuous spacetime will no longer apply, but whatever replaces it must be rather complicated.
 
  • #5
hmmm, this will teach me to take what I read on random internet sites seriously without checking for proper peer reviewed papers. There are so many sites out there that paint this idea of quantized blocks of space as fact.
 
  • #6
jeebs said:
If I'm not mistaken, it is thought that space is divided up into quantized little indivisible chunks, the size of which is called the Planck length.

Also, the space of the universe is thought to be expanding. We could have 2 objects stationary relative to one another at some time t_0, then allow space to expand from t_0 to t_max, and these 2 objects would then be at a greater separation.

Does this mean that each little block of space is itself stretching out (ie. the 2 objects have the same number of blocks between them at t_0 and at t_max)?

Or, is it that they stay the same size, but more blocks exist between the 2 objects at t_max than there were originally at t_0?

the problem disappears if our expanding universe is embedded in a larger 4D static hyperverse.

just sayin
 
  • #7
granpa said:
the problem disappears if our expanding universe is embedded in a larger 4D static hyperverse.

just sayin

I'll have to take your word on that because this means very little to me...
 
  • #8
This is something that i am interested in becasue i recently read that a new theory states that "that space is divided up into quantized little indivisible chunks, the size of which is called the Planck length." I am currently trying to re-find that article.

Is this some new theory with no information or is this something just for us simple mountain men like myself to pass time and sell magazines?
 
  • #9
I have a question about Planck length as the length of a string in String Theory. I understand that a string can be wound in a spiral and, apparently, the Cylinder thus formed will have a circumference of Planck length. At the same time, of course, we've two-dimensionally created a Circle with Planck length as its circumference. But such a circle must then have a diameter that is smaller than Planck length ---and yet there can be no measurement below Planck length. To restate the dilemma, given that the size of a circle is always its diameter, it seems as if we're now find ourselves speaking paradoxically in the form of Buddhist koan ----Can there exist a circle that has no size? (What am I missing here? Help!)
 

1. What is a Planck length?

A Planck length is the smallest unit of length that can be measured in the universe. It is approximately 1.616 x 10^-35 meters and is considered the fundamental length scale of quantum mechanics.

2. How is space quantized?

In quantum mechanics, space is thought to be quantized, meaning that it is made up of discrete, indivisible units. These units are known as Planck lengths and are the smallest possible units of length in the universe. It is theorized that this quantization of space is related to the quantization of other physical quantities such as energy and momentum.

3. What does it mean for space to be expanding?

In astronomy and cosmology, the term "expanding space" refers to the idea that the distances between galaxies and other objects in the universe are increasing over time. This expansion is thought to be driven by the presence of dark energy, a mysterious force that is causing the universe to expand at an accelerating rate.

4. How does the concept of quantized space relate to the expansion of the universe?

The concept of quantized space is closely related to the expansion of the universe in that it helps to explain how the expansion is possible. The quantization of space means that the universe is not infinitely divisible, and therefore there is a limit to how small the distances between objects can become. This limit allows for the expansion of the universe to occur without objects collapsing into each other.

5. How do scientists study and measure Planck lengths?

Currently, there is no experimental way to directly measure Planck lengths. However, scientists can infer the existence of these tiny units of length through observations of phenomena at the quantum level. They can also use mathematical models and theories, such as string theory, to help understand the properties of Planck lengths and their role in the universe.

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