TIME, SPACE-TIME and GRAVITY
Time, space-time and gravity are terms we are relatively familiar with, but the interaction between them is only now becoming of great interest to science.
Time, and it's 'cousin', the space-time continuum are extremely complicated and I do not possess sufficient brain cells to fully understand either term.
So, let's reduce both terms to the simplest possible definition and proceed from there.
In doing so, some specific points may be arguable, but in general, the theory is sound.
We begin by determining that time is somewhat of a paradox.
It's something that governs our daily life. We use it to decide when we get up in the morning, how long to cook an egg, or how early we must leave for work.
But all of these 'times' are arbitrary. They are an approximation of the duration of an event, or a measurable period during which an action, process, or condition exists or continues.
For most of us, the 'second' is the smallest unit of time we normally consider. However, mathematicians and scientists sub-divide these into smaller and smaller units such as milliseconds, microseconds, nanoseconds and so on, and that's where the seeming paradox arises.
When we get down to yoctoseconds, (that is a second divided by 10−24), we find we are unable to measure time as a duration. The duration of the measurement itself, takes place over a period of 'time', regardless of how small that duration might be.
Physicists are very clear that time is not absolute, despite what common sense tells you and me. Time is relative, and flexible and, according to Einstein, "the dividing line between past, present, and future is an illusion".
So reality(or time, if you prefer), is ultimately TIMELESS.
For our purposes, let's just stick with the simple idea that time is the thing that is measured as seconds, minutes, hours, days, years, etc.
With that under our belt, let's tackle the Space-Time Continuum.
Space-time is a universal continuum. That is, a mathematical model that stretches out across the whole universe, where space is three-dimensional and time has the role of the fourth dimension. In short, a sort of 'force field'.
If we imagine this 'force field' as a thin sheet of elastic substance, like a sheet of rubber, it really has no significant effect on the universe itself.
That is, until we introduce gravity.
If we place an object such as a star on our continuum, it warps the field, creating a sort of dip in its surface. The denser the object, the deeper the dip and the more space-time is stretched.
This tells us that not only space can be manipulated and stretched by mass, but so can time.
A ball placed upon our continuum, would roll toward that dip. Moving ever faster as it approaches the object.
Now let's place another object of the continuum at a distance from the first.
Our ball would alter its path and roll toward the closest or largest object. At some point between the two objects, there would be a 'null', or a place where the dips from the two object would cancel each other and the ball would roll toward neither.
Okay, we're ready to place a lot of objects, of various sizes, on our continuum, representing stars, planets, and general space debris. Each object, regardless of its density or distance from it neighbor, would establish null points for each object.
If we carefully manipulate our ball to remain within these null points, it could travel endlessly without colliding with any objects.
This is what keeps our universe in sync, and by carefully manipulating our ball to utilize these dips, and calculating the effects of centrifugal and centripetal forces, we can place a satellite in continuous orbit, or 'slingshot' it into unlimited journeys.
We have now figured out how to get from one object to another with maximum efficiency and minimum expenditure of fuel.
It is this knowledge which enables us to envision travel to distant planets and even stars.
We have achieved some control over space, and even learned how to utilize the forces of gravity, but time still eludes us.
Einstein postulates that the speed of light is the absolute limit, which means that even if we could achieve that ultimate speed, it would still take thousands or even millions of years to reach nearby object outside our solar system.
Possible, but hardly practical.
So, does the dream end here? Will we be forever bound to our solar system?
Luckily there are 'tricks' we can use to work around these limitations.
Chief among these tricks is manipulation of the space-time continuum itself and the interaction of possible dimensions.
Since we know that the fabric of space-time can be 'bent', there is no reason to believe that it cannot be 'folded', much like a piece paper.
Imagine a sheet of paper with two dots placed 6 inches apart.
By folding the paper we can bring those two dots to within the thickness of the paper.
And so it appears with space-time*
Now we, as humans, cannot 'bend' the space-time continuum, but nature can, and experiments indicate that it does.
Furthermore, it appears there may be 'tunnels' connecting those two 'dots'.
These are known as 'wormholes'. Wormholes , called Einstein-Rosen bridges, theoretically create a shortcut that could reduce travel time and distance.
But, (and there is always a but), wormholes bring with them the dangers of sudden collapse, high radiation and dangerous contact with exotic matter.
Another problem is size. Primordial wormholes are predicted to exist on microscopic levels, about 10--33 centimeters. However, as the universe expands, it is possible that some may have been stretched to larger sizes.
It's obvious that there is much we do not yet know, but all indications are that the answers are there, just waiting for us to stumble upon them.
While much of this is unproven and a bit imaginative, there is so much evidence pointing to its truth that we cannot ignore the possibilities.
We also cannot overlook the idea that 'There's more than one way to skin a cat'.
The most popular theory concerns the existence of multiple dimensions, or 'layers' to reality.
At first blush this idea seems to be pure fantasy, but upon closer examination, it would seem to answer many questions which have puzzled us for eons.
Persistent stories of ethereal visions, strange phenomenon and even precognition, abound.
Could they be evidence of other dimensions or realities, of which we are presently unaware?
Next week we will look at this idea of alternate or even duplicate realities.