1
00:00:00,000 --> 00:00:21,000
With the coming into view of a quantum mechanical picture of matter and of all that exists,

2
00:00:21,000 --> 00:00:29,000
many of the traditional ways in which physicists were thinking about nature had to change.

3
00:00:29,000 --> 00:00:36,000
In the pre-quantum world, Newton thought of objects as being made of particles,

4
00:00:36,000 --> 00:00:42,000
and the particles had mass, they had size, they had motion,

5
00:00:42,000 --> 00:00:47,000
then they had other attributes that later were added on, like electric charge.

6
00:00:47,000 --> 00:00:55,000
So the object, and all of these could be measured, so that in a Newtonian picture of physics,

7
00:00:55,000 --> 00:01:00,000
everything was made out of particles and the particles could all be measured,

8
00:01:00,000 --> 00:01:08,000
every aspect of them could be measured, so that the object or the matter was identical to its observables.

9
00:01:08,000 --> 00:01:12,000
Everything you could think about, you could measure.

10
00:01:12,000 --> 00:01:15,000
Quantum mechanics changed that in a profound way.

11
00:01:15,000 --> 00:01:21,000
Quantum mechanics began to show us that whereas matter obviously exists,

12
00:01:21,000 --> 00:01:27,000
the things that are available for us to know about it are limited.

13
00:01:27,000 --> 00:01:34,000
For example, the position and velocity of an object are not simultaneously knowable

14
00:01:34,000 --> 00:01:38,000
with arbitrary precision in the same direction.

15
00:01:38,000 --> 00:01:44,000
So in these ways, quantum mechanics gave us a sense of humility about our level of knowledge.

16
00:01:44,000 --> 00:01:49,000
matter exists, but what it presents to us is limited.

17
00:01:49,000 --> 00:01:54,000
There is only so much we can know about it.

18
00:01:54,000 --> 00:02:03,000
But there has been a very long-standing, and in fact ongoing, question in the field of quantum foundations

19
00:02:03,000 --> 00:02:11,000
as to what is actually going on, what is really happening to matter, so that it behaves in the ways that we see.

20
00:02:11,000 --> 00:02:18,000
For example, there is this simple experiment that people often use to describe quantum mechanics.

21
00:02:18,000 --> 00:02:21,000
They talk about a double-slit experiment.

22
00:02:21,000 --> 00:02:26,000
So in a double-slit experiment, you consider a situation where you have a source of particles,

23
00:02:26,000 --> 00:02:29,000
you have a wall, and the wall are, let's say, two holes.

24
00:02:29,000 --> 00:02:34,000
You close one hole, you look back behind the wall, and you have a detector.

25
00:02:34,000 --> 00:02:38,000
And from this source, you shoot off, let's say, bullets.

26
00:02:38,000 --> 00:02:47,000
Eventually, on this back surface, you see a pileup of incidents, of hits, of events.

27
00:02:47,000 --> 00:02:50,000
When you look at that distribution, you see a hump.

28
00:02:50,000 --> 00:02:54,000
Now you do the experiment again. You open this hole, and you close the other hole.

29
00:02:54,000 --> 00:02:59,000
Now from this one, you do the same thing. You see the same thing. It's just another distribution.

30
00:02:59,000 --> 00:03:06,000
Now the strange thing is that when you open both holes, you expect to see just the sum of the two distributions.

31
00:03:06,000 --> 00:03:09,000
In other words, you know, they would add up together.

32
00:03:09,000 --> 00:03:15,000
But in fact, you see a pattern that looks like an interference, looks like as if a wave went through.

33
00:03:15,000 --> 00:03:22,000
And in some places, what you see is less with both holes open than with one hole open.

34
00:03:22,000 --> 00:03:26,000
How is it that I open the second hole and some go away here?

35
00:03:26,000 --> 00:03:30,000
And this was the first hint that something very mysterious or something very strange is happening.

36
00:03:30,000 --> 00:03:34,000
That there seems to be a wave nature involved as well.

37
00:03:34,000 --> 00:03:44,000
Now the question is, how do we then have a coherent, consistent ontology, which means a description of existence,

38
00:03:44,000 --> 00:03:50,000
that is consistent with both this particle nature and the wave nature?

39
00:03:50,000 --> 00:03:53,000
And that's been a subject of great debate in quantum mechanics.

40
00:03:53,000 --> 00:03:58,000
And I would say at this point, there is not a definite answer.

41
00:03:58,000 --> 00:04:02,000
And this is an area which is still needing a lot of work.

42
00:04:02,000 --> 00:04:10,000
Whereas we know enough about the quantum world to predict the results of experiments extremely well,

43
00:04:10,000 --> 00:04:16,000
we don't have a clear understanding of the underlying things that are going on.

44
00:04:16,000 --> 00:04:27,000
One philosopher and mathematician by the name of Wolfgang Schmidt is proposing a picture these days of quantum mechanics

45
00:04:27,000 --> 00:04:31,000
in which he's invoking essentially a classical ancient picture,

46
00:04:31,000 --> 00:04:38,000
in which it kind of goes back to, for example, what the Greeks would have called the hylomorphic conception of nature.

47
00:04:38,000 --> 00:04:47,000
Whereas the hyla, which is the substrate of matter, and then morph, which is the shape of the matter.

48
00:04:47,000 --> 00:04:54,000
So if you think of a piece of marble, the marble, a big chunk of marble, there is, you can think of a statue as in there.

49
00:04:54,000 --> 00:05:02,000
But until the sculptor actually puts that shape in, carves that shape out of the marble, there is none of that statue in there.

50
00:05:02,000 --> 00:05:05,000
The statue is in there, but it's not really in there.

51
00:05:05,000 --> 00:05:08,000
It's really in the form that the statue is.

52
00:05:08,000 --> 00:05:11,000
But the form without the marble is also not a statue.

53
00:05:11,000 --> 00:05:14,000
So the hyla and the morph need to come together.

54
00:05:14,000 --> 00:05:24,000
So Wolfgang Schmidt kind of uses this to say that in reality there seems to be, at one level, a corporeal world,

55
00:05:24,000 --> 00:05:28,000
in which it's the world of objects we see and sense and touch.

56
00:05:28,000 --> 00:05:33,000
But then in another level there is the world of the physics, of the physicist,

57
00:05:33,000 --> 00:05:41,000
which is something in between sort of this corporeal world and this sort of the highly kind of space,

58
00:05:41,000 --> 00:05:43,000
this Greek highly concept.

59
00:05:43,000 --> 00:05:50,000
And that there is the potentiality that quantum mechanics talks about is really in this in-between state,

60
00:05:50,000 --> 00:05:52,000
which Schmidt calls the physical world.

61
00:05:52,000 --> 00:05:55,000
It makes for a difficult ontology.

62
00:05:55,000 --> 00:05:58,000
It's one that I don't feel like I fully grasp.

63
00:05:58,000 --> 00:06:07,000
But also I can tell you that it tells us there is still a lot of exciting work ahead.

64
00:06:07,000 --> 00:06:15,000
That even understanding the very basic nature of matter is still something that's not fully grasped.

65
00:06:15,000 --> 00:06:16,000
It's a humbling thing.

66
00:06:16,000 --> 00:06:25,000
It says that God created the world with much more depth and detail than our simple approximations

67
00:06:25,000 --> 00:06:28,000
can just dispatch and make it look like, oh yeah, we know everything.

68
00:06:28,000 --> 00:06:31,000
No, there is a lot more to learn.