even time gives you a direction, a way to head forward! Time has a big role to play when we speak about dimensions. A baby would have been a baby if there was no time. There would have been no centuries, decades, years, months, weeks, hours, minutes and seconds if time was not a dimension! So we say that, other than 3 physical dimensions, we have a fourth independent dimension called time. We can feel and measure time as a dimension, even if we cannot see it. Hence, in this four-dimensional world, we have got the three basic independent physical quantities – length, mass, time!
Now, if we talk about higher dimensions, how are we supposed to find them? How are we supposed to prove that they exist, if we can’t feel them? Why do higher dimensions exist? According to laws of mathematics, if we prove a quantity to be independent of all other existing quantities, then we prove that quantity to be another dimension. The problem with higher dimensions is that we cannot see them or feel them, but they do exist. They exist for reason. With the limited physical quantities that we have, it is difficult to express the laws of physics, with all the limitations considered. This is just like a tiger put in a cage! If we look into higher dimensions, the ease of expressing the laws of physics increases, as we will have the freedom of selecting more number of physical quantities. There will be no restrictions on the expression of these laws. Just like, tiger shows all his grace and power when he is left in the jungle where he belongs! In the same way, laws of physics cannot be confined to a few number of quantities. Till now, it is believed that we have 11 such independent dimensions in our universe, but that has only been proved on paper, dimensions which are due to or which lead to the abnormalities in space-time warping.
There is another interesting theory about the dimensions! A theory was proposed in the mid-20th century after the Big Bang theory was proposed. It said that our universe is four dimensional one and is expanding every second. To compensate the energy, we have a twin 6-D universe, besides us, that is shrinking at the pace at which we are expanding. Once that universe reaches singularity, the process is going to get reversed, and that world will start expanding. And our overly expanded universe will undergo reverse- Big Bang! Our little universe will again come close together to reach the ultimate singularity….. So, this is all about dimensions! All you have to do now is, bring out all your curiosity and keep thinking about the dimensions..!!
References: The HYperspace - Michio Kaku