Aquinas and Modern Physics

[lelinator]

I bet you thought that I had forgoten all about this post…nope. However my thoughts on this idea have gone through a number of iterations since you posted it.

My perception of time is that it always moves in one direction - forward.

But isn’t this true of space as well? Aren’t you always moving away from where you have been, and toward where you will be? In this sense, even if you appear to be moving backwards, you’re still moving forwards. So whether it’s from a spatial perspective or a temporal one, you’re always moving away from where you have been, and toward where you will be.

Ah, but you might counter that in the case of space you can always go back to where you’ve been. But that simply isn’t true. Space is constantly expanding, so you can never actually go back to where you’ve been. You can go back to where you were relative to some things, but you’ll be in an entirely different location relative to other things. So motion through space is relative. But because space is expanding, you’re always fundamentally moving forward, although in relation to some things, it may appear as though you’re moving backwards.

And isn’t this also true of time, that any motion through space is accompanied by an equal motion through time, because time dilates in the direction of motion. So as you’re moving through space relative to things, you’re also moving through time relative to those very same things, and in equal measure.

So in both cases you’re always fundamentally moving forward, although relatively speaking, you’re moving toward some things and away from other things.

My perception of space is quite different as I can see a rope extended both forward and backward.

In the case of the rope, it’s extended away from you, both in space and in time. The farther away the rope is, the further back in space and time it is, because they’re both constantly moving forward. Things are always trailing behind you, not just temporally, but spatially as well. So in both cases you’re not looking forward, you’re looking backward, and any perceived directionality is only relative.

 

[AlNg]

because space is expanding, you’re always fundamentally moving forward

Is there a physical law that says that space cannot contract? Time never moves backward toward the past.

you’re not looking forward, you’re looking backward,

If you are at the middle of a long extended rope, there are two directions : left or right. And an ant on the rope can move either way. An ant cannot move backwards in time. The ant can only move one way in time.

 

[Wesrock]

So, if we consider a chicken that comes from an egg, which comes from another chicken that comes from another egg, etc. (a variation of the father and son example), my contention is that there was a first chicken or first egg (but I will let science determine that). I believe this to be the case because I believe that the world was created, and that it was neither infinite nor everlasting. But that things have a beginning in time is an article of faith, not a proposition demonstrated by metaphysics, as St. Thomas said. . . Therefore, if my definition of an essentially ordered series is used in any of the Ways of St. Thomas, it will always work. The arguments of St. Thomas are not jeopardized just because I have a different definition of an essentially ordered series.

You admit to saying your way only works because you believe there was beginning and that belief in a beginning is an article of faith and not demonstrable by metaphysics. Then you say that you can supplement your definition in for St. Thomas’ and it still works. That doesn’t follow, since St. Thomas is not using any article of faith as a premise for his arguments. Assuming an article of faith as a premise undermines what St. Thomas was trying to do with the Five Ways.

And it sounds like you’re simply writing of the principle of proportionate causality, that what is in the cause is also in the effect, and in the case of natural generation the cause is in the effect formally.

It’s just something different. I’m not sure I wantto contimue this line of discussion. At least maybe we’ve cleared up the confusion for others who brought it up.

 

[Dovekin]

our perception of time requires consciousness of motion. It also involves the memory, or the remembrance of what happened before and after. The perception of space requires none of those. In space you can see what is before and after an object; you don’t have to remember it. In time you need to remember because the event in the past is no more. Therefore, we don’t perceive time in exactly the same way as we perceive space.

I am commenting for @lelinator, who is commenting on something like this.

The perception of our “3D world” is a mental construct as much as time is. Depth in particular is not immediately perceived, but is the result of comparng two images, one from each eye. That comparison of images is similar to the comparison of before and after.

There are things we perceive that are clearly embedded in time. Music, for instance. This is similar to our grasp of depth in looking at a tree or a mountain.

 

[rom]

You admit to saying your way only works because you believe there was beginning and that belief in a beginning is an article of faith and not demonstrable by metaphysics.

I didn’t say that my way only works because there was a beginning in the series. What I was saying is that my way would work even if there was no beginning, which would be the case if the series were carried to infinity. Because, if the series were carried to Infinity, the money (the actuality of motion) would remain unexplained if we do not posit the existence of a Prime Mover outside and above the series itself. St. Thomas admits that philosophy alone could not prove that the world had a beginning. But even in that hypothetical case that the world is everlasting and had no beginning, motion in this everlasting world will still remain unexplained without an Unmoved Prime Mover. I did not violate St. Thomas’ proof. I extended it to cover the case that he himself admitted, that is, that the world possibly is an everlasting world.

I’m not sure I wantto contimue this line of discussion. At least maybe we’ve cleared up the confusion for others who brought it up.

That is your privilege. Both of us have already explained our sides adequately, so we may stop. But I will miss you, because you are an intelligent participant in this discussion. Peace.

 

[rom]

The perception of our “3D world” is a mental construct as much as time is.

The “3D world” is, of course, also a concept. The difference is that it is also real and exists outside the mind. Spacetime does not. I already explained this in Post #31 above.

 

[lelinator]

Is there a physical law that says that space cannot contract? Time never moves backward toward the past.

As far as I’m aware there are no physical laws that say time can’t move backwards either. So perhaps it’s just a coincidence that they’re both moving forward. But then again…maybe not.

If you are at the middle of a long extended rope, there are two directions : left or right.

Due to the speed of light, when you look out at the world around you, you’re looking back in time, to what things used to look like.

Due to the expanding universe, when you look out at the world around you, you’re looking back in space, to where things used to be.

And an ant on the rope can move either way. An ant cannot move backwards in time. The ant can only move one way in time.

First, the ant is always moving through both space and time. It can’t stop doing either one.

But every relative motion through space comes with a proportionate motion through time.

If the ant just sits there, then it’'ll move through both space and time in harmony with the things around it. It won’t seem as though it’s moving, but it is. But if the ant starts to move, then it’s motion through space will increase or decrease relative to the position of the things around it. And the same thing will happen with time. It’ll increase or decrease in proportion to it’s motion through space relative to the things around it.

Both the ant’s spatial and temporal position relative to the things around it increases or decreases with motion.

So the two things to remember are that everything is always moving through space and time. And any relative motion through space comes with a proportionate motion through time. What makes it so counter-intuitive is that motion through time is much harder to detect. After all, if nobody told you, you wouldn’t realize that you’re seeing the stars as they existed billions of years ago. And you wouldn’t realize that time passes more slowly for faster moving objects than for slower moving ones.

Time and space are intimately connected, and motion through one is proportionate to motion through the other.

Sorry, I have to go now. Be back tomorrow.

 

[rom]

Another objection mentions no individual changes observed nor the motion of the universe is essentially subordinated chains.

I already replied to this in my Post #85 above. However, I just want to share something that just popped in my head. If you are looking for a chain of essentially subordinated movers and things moved in nature, using the definition given by the Thomists, then I think you will find it very difficult to find many examples. I gave an example of a chain of movers in my post #85 above. Although I think the example represents a chain of essentially subordinated movers, some Thomists will not think so. Because in my example the fruit dropped from the tree because of the action of the wind. The sight of food (the fruit) in turn moved the animal to come and get it. Suppose the motion of the animal happened after the wind stopped blowing. Is the chain of essentially subordinated movers broken? According to the Thomists, yes. According to my definition, no. Because the action of the wind “explains” why the fruit dropped. And it is because the fruit dropped that the animal is moved toward it. To me this is an essentially subordinated chain. To the Thomists, it is not because the wind is not continuously blowing. So, I think the complaint that there are no observed essentially subordinated movers in the universe applies more to their definition than to mine. If the Thomists were to drop the notion of continuous action from the definition of essentially subordinated series of movers, then many more examples will be observed in nature.

 

[AlNg]

everything is always moving through space and time.

Time is not reversible. You cannot go backwards in time.

As far as I’m aware there are no physical laws that say time can’t move backwards either.

With the possible exception of an infinitesimal Planck time unit, as given by the uncertainty principle in QM, it is impossible to reverse time, because if you could go back in time, you could kill your grandfather when he was a child, or your father when he was a child. (I don’t advise this even if you did go back in time, but I am just saying it would be possible for someone to do such.)
OTOH, you can reverse your direction in space. It is not impossible.

 

[rom]

Ah, but you might counter that in the case of space you can always go back to where you’ve been. But that simply isn’t true. Space is constantly expanding, so you can never actually go back to where you’ve been.

You can only say that space is constantly expanding because you have assumed a fixed point of reference. Without it, you will not be able to tell that things are moving away from you, or that the universe is expanding. Since you MUST assume a fixed point of reference, then if you want to locate any position in space, you have to get its coordinates with respect to that fixed point.

Let us now arbitrarily assume that the center of the earth is our fixed point in space, and that all points are measured with respect to it. Consider a point A, with coordinates x1, y1, and z1 with respect to that fixed point. If there is a stone at point A and the stone does not move, then its coordinates at any future time will still be x1, y1, z1. If its coordinates change, then it means that it didn’t remain stationary; it moved.

Now, suppose you are a traveler and you start at point A (the same place where the stone is) at time t1. This means your initial coordinates are x1, y1, z1. Suppose you travel and at time t2 reach another point B with coordinates x2, y2, and z2. This is your new position with respect to your fixed point of reference (the center of the earth). Since everything is moving away from the earth, the stone at your starting point would have also moved to a new point A’, with coordinates x1’, y1’ and z1’. However, the coordinates of your starting point will still be at x1, y1, z1. The stone will no longer be there, but your starting point A is still there with respect to the center of the earth. Theoretically, if you have a vehicle fast enough to overcome the universal rate of expansion, it would be possible for you to return to your initial starting point, which is at coordinates x1, y1, and z1.

You might say, “But the earth is also moving.” Yes, but not with respect to itself. As long as we have already agreed to take the center of the earth as our fixed point of reference, then the earth itself cannot be moving. Otherwise, we have a point that is moving and not moving at the same time, which is impossible.

Therefore, AINg is right. You cannot go back in time, but you can always go back to where you were in space.

 

[Richca]

What do you make of this short video that states the First Way works with Aristotle’s physics and cosmology, but is now invalidated by modern physics? One objection mentions physical changes resulting from gravity, nuclear forces, and electromagnetism do not come about from continual action of an external moving agent, but from intrinsic capacities identified as “fundamental forces”.

St Thomas concludes in the first argument that God is the first mover and God’s activity in creation is metaphysical, not something that can be observed, measured, or quantified by modern science. So, this first objection appears to be based on simply for looking for movers, whether few or many, in the created physical world when the prime or first mover, God, is outside it.

It is a common misunderstanding of Aristotlelian physics that whatever changes or is moved in the physical world is changed by the continual action of a physical external moving agent. For example, Aristotle recognized that the inanimate simple elements, namely, earth, water, air, and fire have natural movements that move of themselves in a certain sense, not like an animal does, without the need for the continual action of some external physical agent. For example, water falls from the sky as rain because water has a natural downward movement due in part to its weight. The per se mover here, Aristotle said, is that which gave the substance of water its form and natural accidents which includes its natural downward movement which is ultimately reduced to God, the creator and maker of all things and preserves everything in existence at every moment. An excellent book concerning this is called ‘Nature and Motion in the Middle Ages’ by Fr. James A. Weisheipl.

A very interesting commentary on Aquinas’ first argument for the existence of God can be found in the rather recent (1963) new translation of the Summa Theologiae by Dominican fathers and published by Cambridge Press. I think Aquinas is using deep metaphysics in the first argument and that is how one must attempt to understand it.

 

[rom]

You can go back to where you were relative to some things, but you’ll be in an entirely different location relative to other things. So motion through space is relative.

Be careful, lelinator. It is not motion itself that is relative, but our measurement of motion. Space and time are not relative. It is how we measure space and time that is relative. Einstein’s theory of relativity is not a relativity of things, but a relativity of the measurement and perception of things.

Suppose you have three physicists, A, B, and C located along the same straight line in space, and that B is midway between A and C. Let us further assume that we are a stationary outside observer and noticed that B is moving to the left with a speed of 5 mph (with respect to us, of course), while A and C are both moving to the right at the speed of 10 and 20 mph respectively (also with respect to us).

Since none of them can detect their own motion, they can each arbitrarily assume that they are stationary. See what happens:

If A assumes that he is stationary, then he would measure that B is approaching him at the speed of 15 mph, while C is moving away from him at the speed of 10 mph. If B assumes that he is stationary, then he would perceive that A is approaching him at 15 mph, but C is going away from him at the speed of 25 mph. If C assumes that he is stationary, he would perceive that A is going away from him, at 10 mph, while B is moving away from him at 25 mph.

Their measurements are all different from each other, and are also different from our own measurement as an outside observer. Each one will have a different measure of motion, not because there is a change in their motion, but because each one is using a different stationary reference to measure their motion. This is not a relativity of motion, but a relativity of how we measure motion. The same is true of space. The same is true of time. Motion, space and time are all absolute. It is the measurement of motion, space and time that is relative.

I have to bring this up because the world is full of muddled thinking. Because of the popularity of the Theory of Relativity, people started thinking that everything is relative, the mind is relative, and that God is relative. They fail to see that Einstein was a mathematical physicist; and that his interest is not the nature of things, but the measurement of the observable features of things. It is now up to us, Catholic philosophers of nature, to clarify the issues, and to untangle the knots where the minds of many are now entangled.

 

[lelinator]

First, let me say that I absolutely love it when people logically think through their arguments. So kudos.

That being said, I’m going to try to logically pick it apart. (That’s my job)

Consider a point A, with coordinates x1, y1, and z1 with respect to that fixed point. If there is a stone at point A and the stone does not move, then its coordinates at any future time will still be x1, y1, z1. If its coordinates change, then it means that it didn’t remain stationary; it moved.

This is true from a relative perspective, but if the universe itself is expanding then although the stone’s relative position hasn’t changed, it has in fact moved. There are two types of movement here, the ongoing movement which applies to all points in the system equally, and the relative movement, which applies between points in the system. Whenever something moves relative to something else, that change in position is both spatial and temporal.

Now, suppose you are a traveler and you start at point A (the same place where the stone is) at time t1. This means your initial coordinates are x1, y1, z1. Suppose you travel and at time t2 reach another point B with coordinates x2, y2, and z2. This is your new position with respect to your fixed point of reference (the center of the earth). Since everything is moving away from the earth, the stone at your starting point would have also moved to a new point A’, with coordinates x1’, y1’ and z1’. However, the coordinates of your starting point will still be at x1, y1, z1.

Relatively speaking, the stone hasn’t moved at all, x1, y1, z1 is in the exact same place as it was before. You either have to apply the movement caused by the expanding universe to both you and the stone, or not, in either case their relative starting positions don’t change. Both the stone’s starting position and your starting position have moved the same relative amount as measured from the center of the earth. The only thing that’s actually moved relative to anything else, is you.

My point is that everything is always moving through both space and time. But within that universal motion there’s relative motion, and that relative motion entails an objects relative position in both space and time. Things move backwards and forwards in both space and time, relative to other things.

And once again I’ve run out of time, so I’ll get back when I can.

 

[Dovekin]

Suppose you have three physicists, A, B, and C located along the same straight line in space, and that B is midway between A and C. Let us further assume that we are a stationary outside observer and noticed that B is moving to the left with a speed of 5 mph (with respect to us, of course), while A and C are both moving to the right at the speed of 10 and 20 mph respectively (also with respect to us).

This is a description from Newtonian physics, which was corrected by special relativity for near lightspeed velocities. While your example holds at the speeds listed, it breaks down as our physicists approach the speed of light. Suppose the speeds are .8c, .9c and .95c instead of 5, 10, and 20 mph, where c is the speed of light.

In your classical system, A would see B approach at 1.7c. Faster than light speed is not allowed in Einstein’s system, so this is an incorrect answer. A sees B approach at about .98c if I have done the math correctly. B is moving away from C at .99c. Velocity is always less than c.

I am not sure how this affects your “world…full of muddled thinking.” People started thinking different speeds are seen by different people looking at the same things, because that is what happens. Understanding our frame of reference is critical. That may be what you mean by “clarify the issues”, i am having a hard time seeing what your point is.

 

[rom]

This is true from a relative perspective, but if the universe itself is expanding then although the stone’s relative position hasn’t changed, it has in fact moved. There are two types of movement here, the ongoing movement which applies to all points in the system equally, and the relative movement, which applies between points in the system. Whenever something moves relative to something else, that change in position is both spatial and temporal.

If the universe is expanding, the stone, originally at (x1, y1, z1), will move to a new position A’ at (x1’, y1’, z1’) because it is an object in space; but its original position (x1, y1, z1) will not move. When it is said that the universe is expanding, it means that all material objects (which include the stone) are moving away from the center of the earth. It does not mean that our fixed point (the center of the earth), and all points in space relative to the fixed point, are also moving. The spatial point (x1, y1, z1) is a mathematical point, not an object in space. It does NOT move with the expansion of the universe because its point of reference is fixed.

 

[rom]

This is a description from Newtonian physics, which was corrected by special relativity for near lightspeed velocities. While your example holds at the speeds listed, it breaks down as our physicists approach the speed of light. Suppose the speeds are .8c, .9c and .95c instead of 5, 10, and 20 mph, where c is the speed of light.

You are correct. If our physicists, A, B and C, are traveling at speeds close to the speed of light, then we need to apply the relativistic equation for adding velocities. But since I used an example where the speeds are way below the speed of light, such refinement is not required. All that is required is simple arithmetic. In fact, even if you apply the relativistic equation for adding velocities in my example, A would still see B approach him at 15 mph, and B and C would still see themselves moving away from each other at 25 mph. So, my example stands unaffected by your objection.

The point of my argument is that it is not motion in the world itself that is relative. It is our mathematical description of motion that varies according to the system of reference used in the description. My contention still stands whether you use Newtonian mechanics or not.

I am not sure how this affects your “world…full of muddled thinking.” People started thinking different speeds are seen by different people looking at the same things, because that is what happens. Understanding our frame of reference is critical. That may be what you mean by “clarify the issues”, i am having a hard time seeing what your point is.

My point is that there is relativity in the description and measurement of things, but not in the things themselves. When you say that A is moving, then you are merely stating the fact that A is in motion. But when you say that A is moving at 10 mph to the right, then you are mathematically describing the motion. And when you describe the motion, it is important that you specify your system of reference, because different individuals will have a different description or measurement of motion depending on the system of reference used. In ordinary life you can say, “I am traveling at 10 mph” because it will be understood as a speed relative to the ground. But if you are a physicist in an empty space where the ground does not exist, and the only other people or objects are B and C, you cannot describe your motion adequately without specifying what you regarded as being stationary. My point, therefore, is that there is relativity in describing the motion of A relative to B and C. But there is no relativity in the fact that A, B and C are moving relative to each other. The observed motion in this world is NOT relative. It is the description of motion that is relative. To think otherwise is “muddled thinking.”

 

[rom]

It is a common misunderstanding of Aristotlelian physics that whatever changes or is moved in the physical world is changed by the continual action of a physical external moving agent. For example, Aristotle recognized that the inanimate simple elements, namely, earth, water, air, and fire have natural movements that move of themselves in a certain sense, not like an animal does, without the need for the continual action of some external physical agent. For example, water falls from the sky as rain because water has a natural downward movement due in part to its weight. The per se mover here, Aristotle said, is that which gave the substance of water its form and natural accidents which includes its natural downward movement which is ultimately reduced to God, the creator and maker of all things and preserves everything in existence at every moment.

Exactly! The essence of a body can be an internal principle of the body’s motion. As a principle of motion, the essence is sometimes called nature. For example, we say that it is of the nature of a bird to fly, that it is of the nature of iron to interact with a magnet, or that it is of the nature of copper to conduct electricity, etc. They usually will not have a visible external cause of motion because the principle of motion is the nature of the substance itself where they belong. Gravity, electromagnetism, and the strong and weak nuclear forces are models that describe some of the properties of a material substance. Unlike ordinary accidents, properties proceed or flow from the essence or nature of the substance. The natural motion of bodies is a consequence of their nature. If there is an external cause (efficient and final) of the natural motion of bodies, it would be nothing else but the Author of Nature itself, who created them. God is the invisible and unobserved efficient and final cause of the being and nature of all things.

In proving the existence of God, St. Thomas did not start with the realities of quantum mechanics. Instead he started with the “more manifest” fact that motion exists in the world. But St. Thomas did not trace a long series of movers and things moved. He made a shortcut. It is like looking for a name, such as Henry Smith, in a phone book. You do not look for it by opening the pages one by one starting from the first page, and reading all the entries line by line until you find the name. Instead you use common sense and do a shortcut. Since the last name starts with an S, you skip all the pages with names that start with A to R, then skip the pages that start with Sa to Sl, and so on. Likewise, St. Thomas simply started with the fact of motion by naming a few examples of movers and things moved. Then, instead of tracing a chain of essentially subordinated movers and things moved, St. Thomas used metaphysical insight and made an intellectual shortcut. He proceeded to build his argument based on the primary notions of potency and act. He proved (a) that whatever is moved, is moved by another; and (b) that a series of essentially subordinated movers demand the existence of an Unmoved Prime mover.

 

[Dovekin]

When you say that A is moving, then you are merely stating the fact that A is in motion.

If your frame of reference is A, then A is not moving. “A is moving” does not mean “A is in motion” but that some people in other frames of reference will see A in motion.

there is no relativity in the fact that A, B and C are moving relative to each other.

I cannot grasp what you mean by this. Motion exists only relative to different frames of reference. In A’s frame of reference, A is not moving. Motion is entirely dependent on comparing frames of reference. Motion, and any description of it, is relative to frames of reference. Motion is always relative motion.

 

[rom]

If your frame of reference is A, then A is not moving. “A is moving” does not mean “A is in motion” but that some people in other frames of reference will see A in motion.

I was only trying to explain to you the difference between simply stating that A is in motion and describing A’s motion. Extreme precision is not required. Read also my comment below.

I cannot grasp what you mean by this. Motion exists only relative to different frames of reference. In A’s frame of reference, A is not moving. Motion is entirely dependent on comparing frames of reference. Motion, and any description of it, is relative to frames of reference. Motion is always relative motion.

No, Dovekin, the description of motion is always relative, but not motion itself. Notice that we have been using the word “motion” in the context of local motion, which is just one kind of motion, and it is the one where the mathematical description of motion is most often applied. In reality, motion is not limited to local motion. There are other physical and chemical changes that we call “motion,” and they are not relative. Within us there is also a consciousness of our motion when we move. I know I am moving when I am moving. In ordinary conversations, I would simply say, “I am moving.” You will never hear me say, “In your frame of reference, I am moving.” You, too, are conscious when you move. Suppose you have a car parked 300 yards away and you ran to get it. Could you honestly say, “Well, it’s all relative to your frame of reference. I could either say ‘I ran to the car’ or ‘the car came to me.’ Both are correct.” Hahaha. Chesterton would easily contradict you by asking: if motion was relative, then why do you feel tired?

 

[Dovekin]

Within us there is also a consciousness of our motion when we move. I know I am moving when I am moving. In ordinary conversations, I would simply say, “I am moving.” You will never hear me say, “In your frame of reference, I am moving.” You, too, are conscious when you move.

In common speech, we use our shared experience as our frame of reference. If I am moving relative to my local experience of the earth, I think I am moving. If I am not conscious of being on a planet, I do not think I am moving around he sun. I project that motion onto the sun, instead of being “conscious” that I am moving.

If A is the frame of reference, A is not moving. He may be conscious of moving relative to other frames, but A is not moving, by definition. In your example, when A is the reference frame, B is moving at 15 mph, C at 10 mph, A at 0 mph. The 5, 10, 20 mph are measured in the Z frame of the narrator; they are not real to the physicists.

Suppose you have a car parked 300 yards away and you ran to get it. Could you honestly say, “Well, it’s all relative to your frame of reference. I could either say ‘I ran to the car’ or ‘the car came to me.’ Both are correct.”

Yes I could honestly say either. I doubt that I would because I share a frame of reference with whomever I am talking with. (wait. Often the car does come to me when someone else is driving…)

I would probably tell Chesterton that all this travelling around the sun tires me out.