# Proof of extra dimension from primordial BHs

• friend
In summary, the article talks about how scientists might be able to detect an extra dimension by looking at the frequency of a pulse that is emitted when an exploding black hole creates mini-black holes. The size of the mini-black hole is directly related to the size of the extra dimension, and this might help scientists figure out which cosmological model is the most accurate.
That's an interesting article, here's something I don't understand in the article:

By analysing the frequency of the pulse, scientists could calculate the size of the extra dimension, which could lend insight into which cosmological model best describes the universe. "The size of the black string is directly related to the size of the extra dimension at the time of the explosion," Kavic says.

How does a dimension have size?! A dimension is a degree of freedom of movement - it's not exactly a measurable quantity is it?

Helical said:
How does a dimension have size?! A dimension is a degree of freedom of movement - it's not exactly a measurable quantity is it?

Think about an ant crawling on an infinitely long garden hose. It has two degrees of movement, X and Y. If it walks along the X dimension, it can keep walking forever. But if it walks along the Y dimension, it can only go about an inch or so before it comes back to its starting point. We can think of the Y dimension as having a "size", or being "small", because although the ant has freedom of movement in that direction, it doesn't have much.

String theory people think of the universe as being ten-dimensional, but they (usually) think that six of the dimensions are "curled up", like the surface of the garden hose. This is how they explain that we don't observe those dimensions-- they are curled up VERY small, like the distance you can travel in that dimension is on the Planck scale and thus undetectable. Sometimes string theorists talk about specialized versions of string theory with "large extra dimensions". When they say "large" in this case they mean, like, a millimeter.

Helical said:
How does a dimension have size?! A dimension is a degree of freedom of movement - it's not exactly a measurable quantity is it?

If you look at a piece of paper, it seems to be completely two-dimensional. In reality, it's just really thin and if you zoom in on it, you can tell that it obviously has thickness.

So even if it looks like it only has an X and Y dimension, it also has a Z dimension. The idea is that if you zoom up on space-time, you will be able to see other dimensions that are too small for us to normally notice.

This obviously isn't a great analogy, since a piece of paper is an object, not a degree of freedom like you said, but then again humans don't have the capacity to visualize these extra dimensions, so this is the best I can give you.

## 1. How do primordial black holes provide evidence for extra dimensions?

Primordial black holes (PBHs) are thought to have formed in the early universe, when conditions were extremely dense and hot. The formation of PBHs is predicted by certain theories that include extra dimensions, such as string theory. If extra dimensions exist, they would affect the formation and properties of PBHs, providing evidence for their existence.

## 2. How can we detect PBHs and study their properties?

PBHs are typically much smaller than regular black holes, making them difficult to detect. However, there are a few ways to indirectly study their properties, such as observing their gravitational effects on surrounding matter or looking for signatures of their evaporation. Future experiments, such as the Laser Interferometer Space Antenna (LISA), may also be able to directly detect PBHs.

## 3. What are the implications of finding evidence for extra dimensions through PBHs?

If PBHs are found to provide evidence for extra dimensions, it would be a significant breakthrough in our understanding of the universe. It could also help validate certain theories, such as string theory, which have long been studied but lack experimental evidence.

## 4. Are there any other possible explanations for PBHs besides extra dimensions?

While extra dimensions are a leading explanation for the formation of PBHs, there are other theories as well. Some researchers propose that PBHs could be remnants of the Big Bang, while others suggest they may be created through the collapse of cosmic strings. Further study and observations will help determine the most likely explanation.

## 5. How does the existence of extra dimensions impact our understanding of gravity?

The presence of extra dimensions would greatly impact our understanding of gravity, as it would require a new understanding of how gravity behaves in these additional dimensions. It could also help reconcile the differences between general relativity and quantum mechanics, which are currently two separate and incompatible theories. Studying PBHs and their implications for extra dimensions could provide valuable insights into the nature of gravity.

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