Infinities and the Many Worlds theory

In summary, the conversation discusses the Many Worlds interpretation of quantum theory and whether it implies an infinity of parallel universes. Some argue that it does, based on the idea that there are an infinite number of possibilities for a photon's trajectory, while others argue that it may be finite depending on the underlying theory. There is also discussion about the implications of classical physics in each parallel universe. Ultimately, it is unclear what implications MWI has for the number of parallel universes, as it is an interpretation of another theory.
  • #1
Gordon Imroth
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Can anyone help me understand a feature of the Many Worlds interpretation of quantum theory, please?

Many people (on this forum and elsewhere) say that the Many World's theory implies infinity parallel universes. I can understand why people think so. For example:

Suppose a photon is sent through a slit to hit a screen at any point. There are infinity points (of the power of the continuum) where the photon can hit the screen, so the Many Worlds theory implies the continuum number of universes, in each of which the photon hits at only one place.

Alternatively, we might say that the number of choices for a photon at any quantum event is always finite, however large. There may be infinity mathematical points on a screen where the photon can hit, but there are not infinity real physical points in space. This implies that space and time are atomic, however, and the problem with that idea is that, in the Many World's theory, classical physics is true in each parallel universe, and classical physics allows the infinite divisibility of space and time.

So my question is: does the Many Worlds theory imply infinity parallel universes, or is it an entirely finite theory? And if Many Worlds is entirely finite, then what happens to classical physics in each universe?

Thanks for your help.

Gordon.

P.s. Suppose we could design an experiment so the trajectory of the photon can follow every possible curve from source to target. As the infinity of curves is greater than the infinity of points on a surface, the Many Worlds theory implies an infinity of greater power than the continuum number.

And as for curves, so for surfaces (perhaps employing multiple photons); and the infinity of surfaces is even bigger than the infinity of curves.

If the Many Worlds theory implies a physical infinity, then what size infinity does it imply, or all of them?
 
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  • #2
Gordon Imroth said:
So my question is: does the Many Worlds theory imply infinity parallel universes, or is it an entirely finite theory? And if Many Worlds is entirely finite, then what happens to classical physics in each universe?
I would say the MWI approach is an interpretation of some other theory, so if the other theory is discrete, then MWI is discrete, and if the other theory is continuous, then so is its MWI. None of that means that there really are an infinity of worlds in MWI-- it seems unlikely that any continuous theory is an exact representation of actual reality. (I feel the same could be said of MWI, but that's a matter of opinion.)
P.s. Suppose we could design an experiment so the trajectory of the photon can follow every possible curve from source to target. As the infinity of curves is greater than the infinity of points on a surface, the Many Worlds theory implies an infinity of greater power than the continuum number.
I don't think there is any meaningful physical way to think about an "infinity of points" on a surface. We can treat the surface mathematically that way, but any actual experiment we use to test our theory is not going to be able to distinguish an infinity of different locations on the screen. "Infinity" doesn't mean anything in physics beyond "a number so large that making it any larger wouldn't have any important consequences." The same can be said about the continuity of classical physics.
 
  • #3
Ken G,

Thanks very much for your reply, and so quickly. I need to go away and think about what you said.

For now, I can say I understand your point that MWI is an interpretation and whether it is discrete or continuous depends on the underlying theory; in which case, what basis do people have for saying MWI implies infinity parallel universes, or (I presume) others say it does not?

What I am looking for is an objection to MWI, which I thought might be that MWI implies infinity parallel universes of many different powers all at the same time.

Thanks again,

Gordon.
 

1. What is the Many Worlds theory and how does it relate to infinities?

The Many Worlds theory, also known as the multiverse theory, suggests that there are infinite parallel universes that exist alongside our own. These universes are constantly branching off from each other based on different outcomes of events, leading to an infinite number of possibilities. This theory is related to infinities because it proposes that there are infinite versions of ourselves and our universe in the multiverse.

2. How is infinity defined in the context of the Many Worlds theory?

In the Many Worlds theory, infinity is defined as the endless number of universes that exist in the multiverse. This means that there are infinite versions of every possible outcome of events, leading to an infinite number of universes.

3. What evidence supports the existence of infinite universes in the Many Worlds theory?

Currently, there is no direct evidence for the existence of infinite universes in the Many Worlds theory. However, the theory is supported by the concept of quantum superposition, which suggests that particles can exist in multiple states simultaneously. This idea lends itself to the possibility of multiple universes existing simultaneously as well.

4. Are there any potential implications of the Many Worlds theory on our own universe?

One potential implication of the Many Worlds theory is that every decision we make could lead to a branching off of a new universe where a different outcome occurred. This means that there are infinite versions of ourselves in different universes, each experiencing a different reality. Additionally, this theory challenges our understanding of causality and the idea that there is one fixed future.

5. Is the Many Worlds theory widely accepted by the scientific community?

The Many Worlds theory is a highly debated and controversial topic within the scientific community. While some physicists support the theory, others criticize it for lacking evidence and being untestable. The theory is still considered to be a speculative concept and is not widely accepted as a scientific fact.

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