Jimmy Akin

What is the nature of time?

Three views have been proposed:

• Presentism holds that only the present is real (so the past and future are not)
• The growing block theory holds that the past and the present are real (but the future is not)
• Eternalism holds that the past, the present, and the future are all real

The Church does not have an official teaching on this, and orthodox Catholics take different views.

However, the Church does teach (as we recently saw) that God is eternal—outside of time—and this seems to have implications for the nature of time.

Let’s suppose that presentism is true and that only the present exists.

What would that mean for God’s eternity?

The Eternal Now and Presentism

In this case, we could speak of two moments that are actually real:

• Outside of time, there is God’s “eternal now”
• Inside of time, there is the present, which we may think of as the “temporal now”

The former is, by definition, changeless, while the latter changes constantly.

At one moment in the temporal now, it’s 8:00 a.m., but a minute later it’s 8:01 a.m., and so forth. At one moment, you’re waking up, at another moment you’re getting out of bed, etc.

How would an eternal, changeless God relate to a constantly changing temporal now, if that is the only moment of time that exists?

Here we run into what strike me as problems. We’ll look at several of them.

Getting the Universe Started

If presentism is true then, in the eternal now, God would create time—a single moment (the “temporal now”) which constantly changes, alongside his changelessness.

One of the things that is constantly changing about time is what the current time actually is. Suppose that God created the universe at 12:01 a.m. In that case:

• At the moment of creation, the temporal now is 12:01 a.m.
• One minute after creation, the temporal now is 12:02 a.m.
• Two minutes after creation, the temporal now is 12:03 a.m.
• And so on.

It follows that God knows all of these things in the eternal now. Thus:

• In the eternal now, God knows that at the first moment of creation it is 12:01 a.m.
• He also knows that a minute after creation it is 12:02 a.m.
• And he knows that two minutes after creation is 12:03 a.m.
• And so on.

By virtue of his omniscience, in the eternal now, God knows what time it will be at all moments after creation—even if those moments haven’t occurred yet.

Now let’s ask a question: Supposing that presentism is true and only the present moment is real, what does God know about what exists?

Notice that we’re not asking about what will exist or what did exist. We’re asking about what exists.

If we ask this question at the moment of creation then we will find the following:

• God knows that he is real, and that he exists changelessly, outside of time.
• God knows that the universe is real, and that in time it is currently 12:01 a.m.

But if we ask the same question a minute later, we will find these things:

• God knows that he is real, and that he exists changelessly, outside of time.
• God knows that the universe is real, and that in time it is currently 12:02 a.m.

We have a problem.

When we first asked the question, God eternally and changelessly knew that the moment 12:01 a.m. exists.

The second time we asked the question, God eternally and changelessly knew that the moment 12:02 a.m. exists.

We have a contradiction.

If only a single moment of time exists then 12:01 a.m. and 12:02 a.m. cannot simultaneously be real. Consequently, God can’t simultaneously know that they are real.

For God to first know that 12:01 a.m. is real and later know that 12:02 a.m. is real, God’s knowledge would have to be changeable, and God would have to be experiencing time.

He would not be timeless.

The same problem appears if we ask about what times God knows are not real. For example:

• At the first moment of creation, 12:02 a.m. is not real because it is in the (unreal) future.
• A minute after creation, 12:01 a.m. is not real because it is in the (unreal) past.

If we asked what God knows about the times that are not real then, when we first ask the question, God would know that 12:02 a.m. is not real (and that 12:01 a.m. is real), but when we next ask the question, he would know that 12:01 a.m. is not real (and that 12:02 a.m. is).

Again, God’s knowledge would be changing with time.

The Underlying Logical Problem

This contradiction happens because we are entertaining the following propositions:

1. God is real.
2. Time is real.
3. God knows what is real.
4. God is changeless.
5. Time consists only of a single, changing moment.

These propositions are not all consistent with each other. Up to four of them can be true, but not all five.

If God knows what is real and what is real changes, then so must God’s knowledge, so God is not changeless.

If you want to accept propositions 1-3 then you must sacrifice either proposition 4 or proposition 5.

Ongoing Change

The same problem reappears when we consider other things God knows.

For example, the way the things in the universe are arranged constantly changes with time.

Even if the total amount of physical energy and mass in the universe stays the same, as modern physics holds, that matter and energy is constantly being rearranged.

Thus there was a time before matter and energy was arranged into stars, a time before it was arranged into living beings, a time before it was arranged into our bodies, etc.

We thus might consider the following:

• At the first moment in time, the matter and energy in the universe was arranged in Configuration 1.
• At the second moment in time, it was arranged in Configuration 2.
• At the third moment in time, it was arranged in Configuration 3.
• And so on.

If we ask our previous question about what God knows is real, it will turn out that—the first time we ask the question—he knows that Configuration 1 is real. But if we ask the same question again, he will know that Configuration 2 is real, etc.

This generates the same kind of problems that we saw above.

God’s Conserving Action

The problem is even worse, because it doesn’t apply just to God’s knowledge. It also applies to his actions.

The Church teaches that the world would not continue to exist unless God sustained it in existence. Thus John Paul II stated:

By creating, God called into being from nothing all that began to exist outside himself. But God’s creative act does not end here. What comes forth from nothing would return to nothing if it were left to itself and not conserved in being by the Creator. Having created the cosmos, God continues to create it, by maintaining it in existence. Conservation is a continuous creation (conservatio est continua creatio) (Audience, May 7, 1986).

This means that, at the first moment of creation, God would generate the universe , with all of the matter and energy in it in Configuration 1.

But then God would have to stop conserving Configuration 1 so that Configuration 2 could come about.

He would then have to stop conserving Configuration 2 so that Configuration 3 could arise.

This would also place God inside of time, since if he were simultaneously conserving all three configurations from outside of time, all three would exist simultaneously from the perspective of the eternal now.

That means all three would be real at once—three different moments of time would exist, contradicting the idea that only a single moment (the present, the “temporal now”) exists.

God would have to be in time if he were to initially create/conserve the moment containing Configuration 1 and then stop doing that to allow Configuration 1 to be replaced by Configuration 2 in the temporal now.

But the Church teaches that God is not in time, so we have another problem.

These aren’t the only problems with the idea that only the present exists. We’ll look at more next time.

(Go to Part 1 | Part 2 | Part 3)

The fact that we live in time and God lives in eternity leads to all kinds of questions. For example:

• If God is eternal and outside of time, does he create all of history all at once?
• Does the fact that what is true in time changes mean that God’s knowledge changes?
• How can God be eternal and yet incarnate as Jesus Christ at a specific moment in time?

To answer questions like this, we need to think about the nature of both time and eternity.

Three Views of Time

Philosophers sometimes talk about three views of time:

1. The view that only the present is real (so the past and the future are not real)
2. The view that the past and the present are real (but the future is not real)
3. The view that the past, present, and future are all real.

The first view is sometimes called “presentism,” since it believes that there is only one moment that truly exists: right now, the present. On this view, the past and the future don’t exist. The moments in the past once existed, and the moments in the future will exist later on, but right now, the only thing that is real is the present.

The second view is sometimes called the “growing block” theory, since it presents time as a block that grows with the course of events. The events that are in the past are real, as are events occurring in the present, at the leading edge of the block, but future events do not yet exist.

The third view is sometimes called “eternalism.” On this view, the past, present, and future are all equally real. The present is the moment of time that we are experiencing right now. We no longer have access to moments in the past, and we do not yet have access to moments in the future, but they still exist.

Which of these theories is true?

Arguments from Physics

A hundred years ago, Albert Einstein proposed that time is essentially another dimension—a fourth dimension, alongside the three spatial dimensions we experience: height, width, and length.

He proposed that, together, these dimensions make up a reality physicists now call “spacetime.”

This concept has served physics extremely well. It makes it easy to describe physical phenomena using equations, and it has proved enormously useful to scientists.

Consequently, modern physicists lean heavily toward eternalism.

The idea of time as a dimension has proved so useful, in fact, that even physicists like Lee Smolin—who wants to revisit the idea—acknowledge it is very hard to imagine an alternative that would make sense. (Smolin talks about this in his book Time Reborn).

It thus seems safe to say that, to the extent contemporary physics is a guide, there is significant support for eternalism.

However, the findings of science are always provisional—never final—so they are not definitive for the question.

Arguments from Philosophy

If the results of physics are not definitive, neither are the results of philosophy.

The debate about the nature of time has been going on since the ancient Greeks began wrestling with the question, and no definitive solution has emerged.

An individual philosopher may find the arguments mounted for one position or another to be the most compelling, but—as on most subjects—there is no definitive consensus among philosophers.

Theology

What I’d like to do, rather than proposing an argument from physics or philosophy, is mount a theological case.

I want to point out right up front that the Church does not have an official teaching on the nature of time, and I know orthodox Catholics who take different positions on the matter.

However, I think that what the Church teaches about God has implications for the nature of time.

So let’s look at that.

God’s Eternity

The Church teaches that God is eternal. The Catechism of the Catholic Church states:

We firmly believe and confess without reservation that there is only one true God, eternal, infinite (immensus), and unchangeable, incomprehensible, almighty and ineffable, the Father and the Son and the Holy Spirit; three persons indeed, but one essence, substance or nature entirely simple (CCC 202).

In popular speech, saying that something is eternal means that it lasts for an unlimited amount of time. However, when applied to God, the term “eternal” means something else: It means he is outside of time altogether.

The classic theological explanation of eternity was provided in the sixth century by the Roman philosopher Boethius, who wrote:

Eternity . . . is the simultaneously-whole and perfect possession of interminable life (On the Consolation of Philosophy 5:6).

This means that God’s life has no end (it’s interminable), and that he possesses all of that life all at once (in a simultaneously-whole manner). He does not experience it moment-by-moment, the way we do. God’s life thus is not spread out over time the way ours is, meaning that he is outside of time.

As St. John Paul II explained:

[H]is eternity . . . must be understood as the “indivisible, perfect, and simultaneous possession of an unending life,” and therefore as the attribute of being absolutely “beyond time” (John Paul II, Audience, Sept. 4, 1985).

He went on to teach:

God’s eternity does not go by with the time of the created world. “It does not coincide with the present.” It does not precede it or “prolong” it into infinity. . . .

He is eternal because he is the absolute fullness of being which cannot be understood as a sum of fragments or of “particles” of being which change with time. The texts quoted from the Bible clearly indicate this.

The absolute fullness of being can come to be understood only as eternity, which is, as the total and indivisible possession of that being, God’s own life.

In this sense God is eternal: a “Now,” a “Present,” subsisting and unchanging.

This mode of being is essentially distinguished from that of creatures, which are “contingent” beings (ibid.).

God therefore exists in what theologians refer to as an “eternal now” outside of time, a now where time does not pass from moment to moment. It is thus distinct from the “temporal now” we experience, where new moments arrive and then slip into the past.

A consequence of this is that there is no change in God. There is no progression from moment to moment in the eternal now, and so no change occurs in God.

This appears to have theological implications for the nature of time.

We’ll look at those next.

(Go to Part 1 | Part 2 | Part 3)