Does Time Exist

Is it possible that the concept of time only exists inside of your head?  General Relativity and Quantum Mechanics are thought to be in conflict with one another and most scientists feel that we need a new, more general theory and they are leaning toward loop quantum gravity, which appears to eliminate time entirely.  General Relativity works great for trying to explain how gravity works on a planetary scale where gravity is a strong force and Quantum Mechanics gives us a good picture of how things work on small scales when gravity is weak.  String Theory is an attempt in theoretical physics to explain the quantum nature of gravity, because it deals with how gravity works at the miniature scale of particles.  String Theory predicts that all elementary particles are, when viewed close-up, vibrating loops and strings.  According to Einstein, matter distorts the very fabric of space and time around it, creating the effect of an attractive force field.  But quantum theory describes all forces in terms of so-called ‘exchange particles’, flitting from place to place.  When the force of gravity is weak, it is described by Gravitons, which are thought to carry the force of gravity in a way that’s similar to how photons carry the electromagnetic force.  Quantum Gravity is thought to be a way for us to make the transition from quantum gravity to general relativity, as this is the marriage of quantum physics with general relativity and this theory may allow us to explain dark matter and dark energy help us unravel black holes and make quantum time travel possible.

In quantum mechanics, time is universal and absolute, steadily ticking along, but in general relativity, time is malleable, relative and dynamical, inextricably interwoven into a four-dimensional fabric known as space-time.  This fabric will warp under the weight of matter, causing nearby stuff to fall toward it and this is how we understand the attraction of gravity, and it will slow down the passage of time relative to clocks that are far away.  When you get on board a rocket to accelerate through space, time dilates, so you will age less than someone who stayed at home.  At the center of a black hole, our best description of gravity breaks down and our other great theory of nature, quantum mechanics, must kick in.  The problem is that larger scale doesn’t come together with the subatomic scale, because we just don’t understand gravity all that well yet.

Quantum gravity is expected to deepen our understanding of space and time, by grasping of the implications for space and time of the quantum nature of the physical world and this was developed to provide a complete and clear-cut answer.  Loop quantum gravity proposes that the fabric of space and time is made of a network of extremely small discrete chunks, or “loops”, but one remarkable aspect of this theory is that it appears to eliminate time entirely.  Every physicist is tasked to describe how the universe appears from the point of view of individual observers, but so far no one has been able to explain just how time appears to pass and some scientists feel that the future does not exist.  The past is generally seen as being immutably fixed, and the future is at least partly undefined, and the present is gone as soon as it arrives.  We don’t know if time is a reality that is independent of the universe, or if it is just a feature of it.  Many think that there is a distinction between past, present and future, and they see that time appears to move in only one direction toward the future, but no one believes that scrambled eggs will ever become whole eggs again, since irreversible processes occur from past to future, thus it is unlikely that time will ever run backward.

Entropy is often taken to be a measure of disorder, and this does not change with time, but entropy has a tendency to increase over time.  Time is viewed as an emergent property, whenever any change occurs anywhere in the universe then time advances forward.  A relational theory about the passage of time, theorizes that its passage is nothing over and above the succession of events, with one thing coming after another, so time is the relation we use when we locate events, like a date that is on the calendar or the time that is shown on a clock.  Relational time presupposes that things are going to change, but since physicists have described our universe as being a block universe where space-time is an unchanging four-dimensional “block”, this conflicts with the view of the world as a three-dimensional space modulated by the passage of time.  Now is a term that indicates that you are in the present, but now does not move or flow.  If time does not flow as we think it does, then time could end up being nothing more than an illusion and our past may not be gone, and our future may already exist.  Science is supposed to give us a refinement of everyday thinking, but since we are missing a clear indication on how to define time, the world does not make much sense.  Unless we can come up with a good account of how time emerges, it is not clear that we can simply assume time exists at any level.  Saying that time does not exist at any level is like saying that there is nothing at all, because our entire lives are built around time.  If you have any thoughts on time, please share them today on Friday Faithfuls.  If you would like to write a poem about time or share a story, or incorporate a time related song into your post, that would be wonderful.