We are accustomed to the three dimensions of our universe - length, width and depth. We can imagine what things would look like in truncated dimensions - on a plane in 2D or along a line in 1D - but imagining what things would look like in more dimensions is difficult (if not impossible). We simply cannot imagine how something is moving in a direction that does not seem to be part of our concept of space. Our Universe has a fourth dimension (time), but it also has only three spatial dimensions. Attention, question:
How would people feel if the number of dimensions in our world changed like the seasons? Let's say that for six months we would live in three dimensions, and for the other six months we would live in four.
Imagine, if you can, that you have the opportunity to move in an additional direction, in addition to up and down, north-south, west-east. Imagine for a start that you are the only one in the world who can do this.
For someone in a 3D world, you could do incredible things that - in many ways - make you godlike:
- you could teleport from one place to another, disappearing in one place and reappearing somewhere else;
- you could rearrange or remove other people's internal organs, performing surgery without the need to open someone's body;
- you could simply remove someone from the three-dimensional universe in which he lives, placing him after a while in another place of your choice.
How is this possible? Imagine that you, a three-dimensional being, are interacting with a two-dimensional universe like an applique kit on a piece of paper.
From the point of view of our extra spatial dimension, we could get inside a two-dimensional being and move its insides without cutting it. We could flip it over, swap left and right. They could have "taken" him out of his universe and placed somewhere else.
And if we ourselves, three-dimensional creatures, decided to get into their two-dimensional universe, we would look strange, since the locals could only see two-dimensional slices at a given moment.
Promotional video:
We would first appear as two footprints
- then would grow into two circles, as we "descend" through their universe,
- the circles would grow until they merged into an oval,
- then other circles (fingers) would appear next to them,
- would grow into two large circles (hands, arms), together with an oval,
- then everything would merge into one large part of our shoulders,
- then it would shrink, grow and dissolve in our necks and heads.
Fortunately, four-dimensional beings do not live in our Universe, since they would seem to us to be divine beings that ignore physical laws. But what if we are not the most multidimensional creatures in the Universe, but the Universe itself has more dimensions than now? It should be noted that this is quite possible; it has been proven that the universe could have had more dimensions in the past.
In the context of general relativity, it is quite easy to construct a space-time frame in which the number of "large" (that is, macroscopic) dimensions would change over time. Not only may you have a large number of dimensions in the past, but in the future you may well have such a chance; you could generally construct a spacetime in which this number will fluctuate, changing up and down over time, over and over again.
For a start, everything is cool: we can have a universe with a fourth - additional - spatial dimension.
So this is cool, but what will it look like? Usually we do not think about this, but the four fundamental interactions - gravity, electromagnetism and two nuclear interactions - have such properties and forces, since they exist in the dimensions that our Universe has. If we were to decrease or increase the number of dimensions, we would change how, for example, the lines of a force field propagate.
If it affected electromagnetism or nuclear forces, it would be catastrophic.
Imagine that you are looking at an atom or inside an atom looking at an atomic nucleus. Nuclei and atoms are the building blocks of all matter that makes up our world, and are measured by the smallest distances: angstroms for atoms (10 ^ -10 meters), femtometers for nuclei (10 ^ -15 meters). If you allowed these forces to “flow away” into another spatial dimension, which they could only accomplish if this dimension reaches a sufficiently large size, the laws of interactions that govern the work of these forces would change.
In general, these forces will have more "space" for dispersal, which means they will become weaker faster at a distance if there are more dimensions. For nuclei, this change will not be so bad: the size of the nuclei will be larger, some nuclei will change their stability, become radioactive, or, on the contrary, get rid of radioactivity. It's okay. But electromagnetism will be more difficult.
Imagine what would happen if suddenly the forces that bind electrons to nuclei became weaker. If there was a change in the strength of this interaction. You don't think about it, but at the molecular level, the only thing holding you back is the relatively weak bonds between electrons and nuclei. If you change this strength, you change the configurations of everything else. Enzymes denature, proteins change shape, ligands disperse; DNA will not be encoded in the molecules it should.
In other words, if the electromagnetic force changes, as it begins to spread into a large fourth spatial dimension, which reaches the size of an angstrom, people's bodies will instantly fall apart and we will die.
But all is not lost. There are many models - mostly developed within string theory - where these forces, electromagnetic and nuclear, are limited to three dimensions. Only gravity can pass through the fourth dimension. For us, this means that if the fourth dimension grows in size (and therefore in consequences), gravity will “bleed” into the extra dimension. Consequently, objects will experience less attraction than what we are used to.
All this will lead to the manifestation of "strange" behavior in different things.
Asteroids, for example - that are locked together - will fly apart because their gravity isn't enough to hold the rocks together. Comets approaching the Sun will evaporate faster and show even more beautiful tails. If the fourth dimension grows large enough, gravitational forces on Earth will greatly decrease, causing our planet to grow larger, especially along the equator.
People living near the poles will feel as if they are in an environment with reduced gravity, while people at the equator will be in danger of flying into space. At the macro level, Newton's famous law of gravity - the inverse square law - will suddenly become the inverse cube law, greatly decreasing gravity with distance.
If the measurement reaches the dimensions of the distance from the Earth to the Sun, everything in the solar system will be untied. Even if it only lasts a couple of days a year - and if gravity is normal every three months - our solar system will completely collapse in just a hundred years.
There would come a time on Earth when we would not only be able to move an "additional" path through space, when we would acquire not only an additional "direction", in addition to up-down, left-right and forward-backward, but also when the properties of gravity changed would be for the worse. We would jump higher and further, but the consequences for the now stable universe would be apocalyptic.
Therefore, it is definitely not worth dreaming about the appearance of the fourth dimension. However, there is also a positive note. We wouldn't have to worry about global warming, since increasing the distance to the Sun would cool our world dramatically, faster than rising atmospheric carbon dioxide heats it up.
Ilya Khel