Question about Space -- Is Space itself a 4th dimensional object?

In summary, the instructor referred to how the universe is expanding, and so much so that there are places we could never ever get to because it's expanding fasterling than the speed of light. Anyways, this got me thinking about Space itself and I was wondering. Is Space in of itself a 4th dimensional object? Because clearly it can't be NOTHING if it is expanding... right?
  • #1
SaniT404
3
0
Ok, so I was just in physics class today and we were talking about special relativity... anyways, the instructor referred to how the universe is expanding, and so much so that there are places we could never ever get to because it's expanding fasterling than the speed of light. Anyways, this got me thinking about Space itself and I was wondering. Is Space in of itself a 4th dimensional object? Because clearly it can't be NOTHING if it is expanding... right? It's just intangible to us... so couldn't it just be a really big object perpendicular to the 3d matter on/in/around it?
 
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  • #2
The local topology of our universe is 3-dimensional so spacetime also has 3 spatial dimensions.
 
  • #3
SaniT404 said:
the instructor referred to how the universe is expanding, and so much so that there are places we could never ever get to because it's expanding fasterling than the speed of light.
This is not quite correct. See:



SaniT404 said:
Is Space in of itself a 4th dimensional object?
Space-time is 4D, space is 3D

SaniT404 said:
Because clearly it can't be NOTHING if it is expanding... right?
See this similar question:
https://www.physicsforums.com/threads/on-space-time.783833/
 
  • #4
Space is 3D where we have (x,y,z), then we add the third component, time or t, then we have (t,x,y,z) a 4D; which is why we call it Space-time. This t is most affected by massive objects such as black holes which not only bent space but also time.
 
  • #5
SaniT404 said:
Is Space in of itself a 4th dimensional object? Because clearly it can't be NOTHING if it is expanding... right?
No, space is not a thing. The expression 'space is expanding' is a misnomer. It is more accurate to say the distance between distant objects is expanding.
 
  • #6
So what I'm getting... that time is the 4th dimension, which is what I always thought. But then I saw several other places that changed the way I saw it. The first dimension would be considered a line. 2nd dimension is a square, which is simply a shape perpendicular to the 1st dimension. We can all agree with that as well, yes? So the third dimension is perpendicular to a square, or the second dimension. So the fourth dimension must be perpendicular to the third. That's where the tesseract come from. A 4d cube. If I'm correct, this is what the string theory operates on, 11 dimensions, all perpendicular to the dimension before it. So how then is time the 4th dimension... these 2 theories, einstein's and the string theory seem to conflict...
 
  • #7
Those dimensions are all spatial dimensions, and some of the string theory ones are very weird indeed. String theory is not an accepted mainstream theory (meaning that there's not enough evidence to use it over competing theories) at this time, so even though string theory and GR conflict, we don't have a problem. GR has plenty of observational evidence to support it over competing theories. String theory has little if any.
 
  • #8
Drakkith said:
Those dimensions are all spatial dimensions, and some of the string theory ones are very weird indeed. String theory is not an accepted mainstream theory (meaning that there's not enough evidence to use it over competing theories) at this time, so even though string theory and GR conflict, we don't have a problem. GR has plenty of observational evidence to support it over competing theories. String theory has little if any.
Ok, thanks, that helps alot!
 

1. What do you mean by "4th dimensional object" in relation to space?

In this context, a 4th dimensional object refers to something that exists in the 4th dimension, which is a theoretical dimension beyond our three dimensions of length, width, and height. It is often used to describe abstract concepts or phenomena, such as time or space itself.

2. How do scientists know that space is a 4th dimensional object?

Scientists do not currently have concrete evidence that space is a 4th dimensional object. However, many theories, such as the theory of relativity, suggest that space and time are interconnected and cannot be fully understood without considering the 4th dimension.

3. Can we physically observe the 4th dimension in space?

No, it is not currently possible for us to observe the 4th dimension in space. Our human senses are limited to perceiving only three dimensions, so we cannot directly see or experience the 4th dimension. However, scientists use mathematical models and theories to understand and study the concept of the 4th dimension.

4. How does the 4th dimension affect our understanding of space?

The concept of the 4th dimension challenges our traditional understanding of space and forces us to think about it in a new way. It allows us to explore ideas such as the curvature of space, the expansion of the universe, and the concept of spacetime. Understanding the 4th dimension can also help us better understand the fundamental laws of physics.

5. Could there be more than 4 dimensions in space?

Some scientific theories, such as string theory, suggest that there could be more than 4 dimensions in space. These dimensions are often referred to as "hidden dimensions" or "compactified dimensions" and are believed to be too small for us to perceive. However, this is still a topic of ongoing research and has not been confirmed by scientific evidence.

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