Name: What Is Time? Determinism, Quantum Physics, Consciousness, Information, Free Will, Causality...
Uploaded: 2015-07-11T06:36:23.000Z
Duration: 31 min 18 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Adverbs of manner

This is probably one of the most difficult questions you can ever ask a physicist or

philosopher... I am not a physicist - yet - nor a philosopher, but here I am, little

old me, not only wondering about the nature of time, but also making a first ever Youtube

video about it. My aim is to make you think, to create discussion... And of course, I hope

The answer to what time is may be as simple as "Time is what the ticks of a clock measure"

or "Time is what keeps everything from happening all at once". But let's dig a little bit deeper

Let's start with Newtonian time. Newton's view of reality implied that time was external

and absolute. Newton's time is a kind of container, where events take place in a completely deterministic

way, linearly and independently of the observer.

Then came Einstein. His theory of special relativity, and then general relativity, both

led to the conclusion that time is relative to the observer. Time depends on where you

are and how you move relative to others. There is no such thing as universal time. Space

and time are constrained by c (the velocity of light) in such a way that the "now" of

one observer is not the same as the "now" of another observer. Mass, equally, can also

Time dilation and length contraction are not just theoretical constructs within an elegant

theory. These effects have been tested again and again without failure; at macroscopic

scales, Einstein's theory has been shown to be a very good model of reality.

Let's talk about time dilation with an example. We have the elementary particles called muons,

which have a half-life of around 1.5 microseconds. That means that if we have, say, 100 muons

in the lab, after 1.5 microsecond has elapsed, we will have, on average, 50 muons left. The

other 50 will have disintegrated. After another 1.5 microsecond, we will have, on average,

These particles are produced at the edge of our atmosphere due to incoming cosmic rays

hitting air molecules. They are constantly produced so there is a constant fall of muons

towards the Earth's surface, travelling at nearly the speed of light. What is observed

experimentally is that more muons are detected than one would have expected, when we consider

This fact can only be accounted for when we use the model of time and space given by Einstein's

special relativity theory, where time and space are constrained by c, the velocity of

light, and so times and positions are relative to the observer. In this case, from our point

of view, the muon's own time appears dilated. More of them can reach the earth's surface,

from our perspective, because a second of their time lasts longer than a second of our

So we can see that from the very beginning of last century, the concept of absolute time

was shattered, and time was understood as being completely dependent on the observer.

Newton's absolute time is only a good approximation, when speeds are low and when we can effectively

Now, let's take a look at the concept of time from a philosophical point of view. We have

what is called the A theory of time and the B theory of time. These were introduced by

the philosopher John McTaggart at the beginning of last century as well.

The A theory of time says that the only "real" time is the present; the past is gone and

the future exists as just a probability distribution, a potentiality of possible things that can

happen. There is no set future - on a kind of imaginary line "laid out there" for us

- just waiting to happen. Therefore, the future is not "real".

On the other hand, the B theory of time says that past, present and future all co-exist,

and are as "real" as each other. The B theory says that the distinction between past, present

and future are just an illusion of consciousness.

One of the consequences drawn by many orthodox physicists as a result of either Newtonian

physics or relativity theory is that determinism is a fact. That the past completely determines

the future, and hence, all what has happened since, say, the big bang, was determined by

the initial conditions, including you and me and our actions, thoughts and feelings.

There is no room for free will, which is seen as just an illusion, when we take this deterministic

Hence, it seems that it is the B theory of time, not A, the model of time that most closely

agrees with the classical equations of physics.

So... It appears that common sense agrees with A Theory, but classical physics agrees

with B Theory. Could it be that time is a bit more complicated than what A or B theories

of time suggest? That reality is a mixture of the two ideas? Could it be that a linear

model of time is not a good approximation of reality? We will explore this issue in

a bit when we talk about Quantum Physics.

Now - before going into quantum physics - let's take a little break. How do I personally think

of time? What is my own experience of time?

On a personal level, I intuitively feel that time is not some mysterious external dimension

or construct that flows in the forward direction, that kind of dictates in what order events

can happen, but I feel that it is rather a much much more fundamental concept, even more

I see time as a concept that is intricately linked to the individual's perception of change.

I think of time as "the perception of duration, of change and the ordering of events" by a

living entity or, in fact, you could say, by a conscious entity (here I'm defining consciousness

in line with awareness, hence animals and primitive organisms would have their own concept

of time, depending on how they perceive change).

On the other hand, I do not see time as a strict illusion either, nor as a block of

events completely determined beforehand. I see it as a pliable tool which, when used

within this particular universe, it enables our experience of 3D space and the perception

In this way, I often ask myself that, if time can be thought of as the perception of change...

what happens when there is no change and no perception? Imagine you are somehow still

conscious, but confined in a universe where nothing ever happens and you have no perception

of any change whatsoever occurring (this reality would obviously be nothing like our physical

What are you left with? The first thing that comes to mind is that time does not make sense

in such a universe, it does not exist, unless change can be perceived by some sort of being

or beings that populate it so that some order can be assigned as to what goes first, what

goes after, etc. Maybe time could be thought of as a perpetual "now" under those conditions.

And all these thoughts obviously bring up the idea of universal versus relative or,

we could say, individual time. However, here we are talking of ideas beyond Einstein's

relativity theory. We are not talking about time and space in our physical universe obeying

certain rules, whereby c, the velocity of light, and mass, restrict how space-time behaves...

but in addition to this, we are talking about time being something that is meaningless in

the absence of an entity / a being (or a consciousness, an awareness) who is able to perceive change,

therefore being able to assign a "before" and an "after" to events that occur.

The other idea that I often wonder about, and that I feel is very important too is:

are space and time fundamental? If so, are they equally fundamental? Could it be that

I intuitively see time as more fundamental than space. I can sort of picture a reality,

a state (let's say a state outside of this universe) where space does not exist but time

does, where only patterns of "states" exist and there is a chronological order that can