Before I begin,
it should explained why understanding the nature of time is seemingly important. Unlike
the strong and weak nuclear forces, electromagnetism and to a certain extent,
gravity, we have extremely limited control over time. To understand time would
potentially allow us – or whomever controls the knowledge or technology – to
gain one more advantage over nature. If the nature of time could be understood,
it is assumed we could control or at least manipulate it. Based upon our
current understanding of physics and cosmology, I believe I’ve come to
understand the nature of time. Equally important is that in understanding how
time works, this understanding destroys the extravagant notion of time travel*
altogether.
[*Time travel
into the past, that is. Time travel into the future is known to be logically
possible, but this concept of time travel is not regarded as ‘sexy’ because it
does not allow any control or interaction with the past, much less the ‘now.’]
Why would we
think time travel is possible in the first place? Human beings have been the
stewards of impossible ideas for a long time and time travel is no exception.
It is an even more bizarre thing to contemplate time travel when you take some
of the most popular theories of time into consideration. For example, in the
B-Theory of Time aka Tenseless Time or Eternalism, it is hypothesized that the
past, present and future exist all at once and this would certainly not allow
time travel. The B-Theory of Time is most likely a false hypothesis given Einstein’s
Theory of Special Relativity as it relates to the relativity of simultaneity and
time dilation due to the effect of gravity (it is well confirmed that time runs
differently, say, near massive objects as opposed to further away due to
gravity). A similar criticism can be leveled against what is called Block Time,
in which it is hypothesized that the past and present are real but the future
is not; that the future amounts to an ever shifting ‘now’ that somehow leaves a
trail of breadcrumbs we could potentially go back to and pick up. There’s less
of a problem with imagining that only right now exists given anyone’s
perspective from any point in three dimensional space, though upon reflection,
what now is there? For as soon as it is now, now is in the past. This last
point brings us to whether or not there is a flow to time.
Does time flow?
That is, does time flow like a river or it does it manifest as a series of
infinitesimally small pieces, like a quantum-sized roll of film? While some
scientists believe that the latter is the case and have scaled packets of time
down to what is called Plank Time (trust me, a super-duper small measurement)
there is no explanation as to how one frame of time ‘becomes’ or seemingly ‘flows
into’ another. It also seems odd that any scientist would insist on dividing
time into packets since this would make time appear to be unlike anything else
in physics; the strong and weak nuclear forces, electromagnetism and gravity
are not even matter are cleanly divided into packets. (Of course, just because
the others are not a divisible ‘something’ doesn’t necessarily rule this out of
time’s nature.) Where would solid matter even go during the intervals in which
time changes in this view? If on the other hand time is part of a fabric that comes
from the stretching of space, this would appear to make more sense as there would
be a connection between space and time that makes it plausible that any
interaction with gravity would have differing effects. These differing effects
are what ultimately causes time to flow in the only direction we have ever
known – forward. Thus, whether or not time flows is rather irrelevant; it’s the
seemingly forward direction of time that matters*. And, the reason why time
only goes in one direction is because it is an emergent property of the
expansion of space and not a dimension unto itself.
[*On the
macroscopic level of organization in which we interact with the world. Time
appears to have little meaning in the subatomic world, though overall this has
little impact on time as we experience it.]
In trying to
understand time, people seem to overthink or want to complicate the answer as
to its nature because time is so hard to pin down, metaphorically speaking. Anything so elusive must be difficult to
understand, is what conventional wisdom seems to want to say. But the
question and answer are not intractable. What is time? It is the perception or
measurement of space and matter in relationship to each other. Time is observed
as changes in the differences between these two aspects of nature. And these
things change in relationship to each other – all the time – because space
itself is always expanding.
We know that on
both a cosmic and local scale, space itself is expanding and doing so in every
direction (thus there is no ‘center’ to the universe). It is also expanding at
a speed per distance in every
direction that is faster than the ability of light to transverse already
interstellar distances, which is about 70km/sec per megaparsec and accelerating
(we’ll see what this has to do with anything soon). Because of this, most
galaxies are getting further and
further away from each other (and not themselves necessarily ‘moving’ away from
each other). Keep in mind for a moment that the expansion of space at the
subatomic and local scale is overcome – that is, not taking place or doing so
imperceptibly – due to the strong and weak nuclear forces, electromagnetism,
and even gravity whereas massive objects like a planet, solar system, or galaxy
is concerned. In deep space, space itself is expanding (more rapidly than at
the subatomic and local scale) and as it expands, the change of objects in
relation to each other changes. These changes are perceived as the passage of
time. For example, in the smaller confines of space, such as within the area of
a galaxy – which is small, cosmically speaking – a galaxy’s position changes in
relationship to everything else in the universe and because the matter therein
changes in relation to space – which is not static in any direction – this is
what we construe as time. Even if space were not expanding and instead were
collapsing, we would still see the arrow of time go forward because of the
different arrangement of matter in relationship to space. (Or in another
scenario, we would be unable to tell if time were flowing backwards or forward
since we’d be part of the changes taking place. And now you’ve just realized
that, heck, that means time could be flowing backwards right now and we wouldn’t
know it.)
Meanwhile, as
space expands and matter spreads itself out (for the most part) on the cosmic
scale, the Earth is moving through space around the Sun at 30km/sec, the Sun is
moving around the center of the Milky Way at about 200-250km/sec, and the Milky
Way is moving approximately 600km/sec toward the constellation Hydra. This,
too, provides us with a positional change between objects that we can observe
and measure. Notice if you will how often scientists assert that time and space
cannot be separated; this is a bit confusing because it is an incomplete
assertion: time and space and matter
altogether cannot be separated if time is to be observed and measured. Time and
space may exist on their own together, but to do so would be irrelevant to the
matter of which we are comprised. You will likewise hear scientists say that
time didn’t exist before the moment the universe came into existence. As space
came into existence after quantum fluctuations supposedly caused the Big Bang
(or Big Bounce depending on what theory you want to go with), matter formed as
space expanded and cooled, providing the universe with time as we know it*.
[*We’re not
exactly sure how the Big Bang or Bounce could happen as quantum fluctuation
would suggest the necessity of the passage of time. But it appears that the
so-called arrow-of-time means little if nothing at the subatomic scale or at
least little or nothing to massless particles such as a photon. Empty space,
teeming with energy – meaning it’s not really
empty – doesn’t rely on a direction of time for changes. I do realize this
seems counterintuitive for those of us who live at the macroscopic level since
we perceive changes as going forward in time. Quantum physics doesn’t play by
the same rules, apparently.]
What implications
does this hold for time travel? It makes time travel, at least to the past,
impossible. (How could you use ‘forward’ time to go back in time anyway?) Space
and time and their relation to matter do not allow for a ‘map’ in which there
are points in the past we can revisit on a whim. Due to the expansion of space
and the movement of matter within space – which is a drive towards the equal
distribution of matter and energy in the universe – the position of the matter
within the universe is constantly changing; to visit the past would necessarily
no longer be the past we knew, but a new past that included the input of (our)
new matter into the initial position of matter within the universe at the time
in question. Some might speculate that to do such a thing would result in a new
timeline/alternate universe, but there is no evidence to suggest creating an
alternate timeline or universe is possible. Hence, to “go back in time” would
be paradoxical and paradoxes are by definition impossible.
As I alluded to
in passing several times now, quantum physics doesn’t play by the same rules of
time that we are used to. Massless particles such as a photon, light, do not
have experiences in the traditional sense because they are not directly
affected by the forces that dictate the behavior of particles with mass. A
photon can be pulled into a blackhole because of the curvature of space due to
extreme gravity, but gravity has no direct effect on a photon. The curvature of
space is what appears to make a photon – something that experiences no time –
to experience time, by changing the photon’s position because space around it
expands and/or curves. Although a photon has no mass (and can therefore exert
no gravitational force or, again, be directly affected by gravity) and is essentially
‘frozen’ in time, it is perceived to experience the passage of time due to
space expanding through the photon’s fixed points. All of this is to once again
say and add to that, that not only is time a derivative of the expansion of
space, but is an emergent property of changes to the positions of mass and massless particles due to the
expansion of space while gravity curves that space.
Time travel to
the past is not possible unless we can reverse the expansion of space and un-curve
space to put mass and massless particles back in their previously experienced
positions. Even if we could do this, we wouldn’t know that we’ve done it because
we would all be in the same state we originally experienced. Again, if time
were actually running backwards right now and the so-called arrow-of-time is
just a phrase for the direction time flows, we wouldn’t know it because it is
normal to our experiences. In my conception of time, none of the legendary
logician Kurt Godel’s (1906-1978) ‘light cones’ are allowed to ‘tip over’ due
to extreme curvatures of space and allow information or you to travel to the
past.
Given this
conception of time, some questions remain (though all are not directly tied to
the nature of time itself). If it is assumed by cosmologists that approximately
80-90% of the universe’s mass is missing, how does this missing mass affect
time, if at all? (Perhaps it isn’t missing and something we haven’t thought of
is overcoming gravity to drive the expansion of space, though, Dark Energy is
the name of this clandestine force I suppose yet sounds too precise for
something totally unknown). It would also be interesting to know how consciousness
allows us to perceive the passage of time.
Naturally, this
theory of time as I have formulated it is without a certain level of
preciseness as I am not a physicist. My theory, though, makes far more sense
and possesses more explanatory power than other theories such as the B-Theory
of Time or Block Time, both of which are not confirmable.
Time only goes
in one direction, expanding so to speak, and this doesn’t allow for time
travel. But don’t shoot; I’m just the messenger. Go back in time and kill me
before I figure all this out if you don’t believe me. (Or, more courteously, simply
point out where my argument fails. Thanks.)
