The Present Moment
Only the present exists. Everything else is a record of it, or has not happened.
The past is kept in records or nowhere at all. A memory is a pattern in a brain now; a fossil is rock now; a photograph is ink now. Every trace of the past that anyone has ever found is a present object, which is why knowing about the past and the past existing are different claims. And a complete record could not be kept inside the universe in any case: it would need about 10151 pieces of information against the 10123 available.
None of this is new. Two schools of Buddhist philosophy argued precisely this question for six hundred years from the second century, one holding that past and future exist and the other that only the present does. Augustine reached the same place around 400 AD. What none of them proposed — what nobody proposed until 1905 — is that the present moment might differ from place to place.
Two things are deliberately left out. Clocks disagree when they move or sit near a mass, which is real and is memo E.13. And relativity holds that distant events have no single answer about happening together, which is the strongest argument against everything here and is memo T.2.2. Neither is answered in this one.
What this memo does and does not do
It argues that only the present exists, that the past survives only as present records, and it calculates that a complete record of every past moment could not be held inside the universe — short by a factor of 1027.
It does not establish that the present is universal. That is the claim, not a result. The argument against it — that relativity leaves no fact about what is happening now — is conceded in section 8 and answered nowhere yet.
Draft. A working draft, published for scrutiny rather than as a settled result.
This memo is about the present moment and nothing else. Two matters that belong to time are deliberately left out: what clocks do when they move or sit near a mass, which is memo E.13, and whether two distant events can be said to happen together, which is memo T.2.2. Both are conceded here in a paragraph and argued nowhere in this one.
1. Only The Present Exists
The claim is as plain as it can be put. The universe is in one arrangement at a time, and that arrangement changes. There is no other arrangement anywhere — not one behind it, not one ahead of it.
What we call the past is the arrangement it used to be in. What we call the future is an arrangement it has not been in yet. Neither is a place. Neither is stored.
The screen
Think of the universe as a three-dimensional screen showing one image. The image is everything there is: every particle, everywhere, in the position it is in.
The image changes. When it does, the previous image is not filed somewhere or moved into a back room. It is simply not the image any more. There is one frame, and it is always the current one.
This is not a projector with a reel of film waiting to be shown. A reel would mean the future already exists, wound up and queued. There is no reel. The screen is not showing anything from anywhere — it is just the arrangement the universe is in.
2. Where The Past Is Kept
In records, or nowhere at all.
Every trace of the past that anyone has ever found is a present object. A memory is a pattern in a brain now. A photograph is ink on paper now. A fossil is rock now, arranged in a shape that something living once had. Light from a distant galaxy is light arriving now, carrying a pattern from when it left.
| What we call it | What it actually is |
|---|---|
| A memory | A pattern in a brain, present |
| A photograph | Ink on paper, present |
| A fossil | Rock in a shape, present |
| Starlight from a million years ago | Light arriving now |
| A tree ring | Wood, present |
| Anything not recorded | Gone |
This is why nothing is in conflict
People sometimes object that the past cannot be gone, because we clearly know things about it. But knowing about the past and the past existing are different claims.
A record is always a present thing. We read the record, here, now, and work out what must have happened. Nothing about that requires the past to be somewhere.
And it explains what we actually find. There is no way to reach the past — only ways to read what it left behind. If the past were a place, that would be strange. If the past is gone and only its marks remain, it is exactly what you would expect.
What is not recorded is not filed elsewhere. It is gone. Most of what has happened has left no trace at all, and there is nowhere it could be waiting.
3. Could Everything Be Recorded Somewhere?
It is a serious question and it has a definite answer for anything inside the universe.
There is a limit on how much can be stored in a region — not a practical limit but a physical one, set by the size of the region. For the observable universe that limit is about 10123 pieces of information.
Recording the arrangement of everything, at every moment since the beginning, would take about 10151.
Short by a very long way
That is not a shortfall of a few per cent. It exceeds what the universe can hold by a factor of 1027 — a thousand million million million million times over.
So a complete moment-by-moment record of the past cannot be kept inside the universe. What we have instead is what we observe: a partial record, full of gaps, in fossils and starlight and memory.
A complete record held outside the universe is untouched by this argument, because nothing inside can measure, bound or test it. That is a different kind of claim and this memo does not argue it either way.
4. The Future Is Not Yet Made
The future is not a place you have not reached. It is an arrangement that has not happened.
The distinction matters. If the future is a place, then it exists and you are travelling toward it, and what you will do tomorrow is already the case. If the future is simply what has not happened, then it is made as it arrives, out of what is here now.
This memo takes the second. The only thing that exists is the present arrangement, and the next one will be made from it.
5. Time Is Duration, Not A Direction
Time is often drawn as a line you move along, like a road, with the past behind and the future ahead. That picture is useful and it is also the source of a great deal of confusion, because a road has places on it whether you are standing there or not.
On this account time is not a direction at all. It is duration — the fact that things change, and the measure of how much.
What would remain if nothing changed
Imagine everything stopping. Not people stopping, but every particle everywhere frozen in place, with nothing moving at any scale.
Nothing would mark the passing. No clock could tick, because a clock works by something moving. No process could advance. There would be no way, even in principle, to say how long it lasted.
That is the sense in which time is not a thing in its own right. It is what change amounts to. Stop the change and there is nothing left over that is still flowing.
6. Everyone Who Looked Found The Same Thing
The idea that only the present exists is often treated as a naive first impression that careful thought gets over. The record shows something different: it was examined in detail, argued over for centuries, and defended.
Two schools of Buddhist philosophy fought over precisely this question from about the second century.
| School | Position | In modern terms |
|---|---|---|
| Sarvāstivāda “the theory that all exists” | Things exist in past, present and future alike — the “three times” | The block universe |
| Sautrāntika | Only the present moment exists. Past and future are constructions of the mind | This memo’s position |
The argument ran for six hundred years. The Sautrāntikas held that the other position contradicted the most basic principle they had, that nothing persists. Nagarjuna set out the dispute in the second century, and an older text put the position in six words: the past and future are not; the present and the unconditioned exist.
Around 400 AD, Augustine reached the same place from a different direction. He argued there are not three times but three presents: the present of things past, which is memory; the present of things present, which is sight; and the present of things future, which is expectation. All three are now.
And this is the part that matters
Those schools disagreed about almost everything. They disagreed about whether the past exists, which is the whole of the dispute above.
Not one of them suggested that the present moment might be different in different places. Whatever they thought was in it, they took for granted there was one of it, everywhere, at once. So did Augustine. So did every tradition that left a record.
Nobody proposed otherwise until 1905, and that proposal rests on a particular way of setting two distant clocks — a matter section 8 returns to.
7. What The Contemplatives Report
There is a second body of observation on this, from people whose entire method was the direct examination of experience, sustained over a great many years.
What they report is consistent across traditions that had no contact with each other: the present is singular and immediate; the past is reachable only as memory; the sense of passing is unbroken. Not a belief about time but a description of what is found when attention is turned on it closely.
Why that counts, and how far
It counts because it is a fact that needs accounting for. If every moment exists equally, as the block universe says, then why is one of them lit up, and why does the lit one move? That is a recognised difficulty and not a fringe complaint. The account in this memo has no such problem: the present is singular in experience because it is singular in fact.
And here is how far it goes. Looking closely at your own experience establishes that your present is singular. It does not and cannot establish that the present is singular across the universe — no amount of attention to what is here reaches Andromeda.
The contemplatives assumed one present everywhere, as everyone did. They did not check it, because nobody thought to. What their observation supports is the first half of this memo, not the claim that section 8 leaves open.
8. Two Things This Memo Does Not Settle
Both are real, both are serious, and neither is argued here.
Clocks disagree. A clock that moves runs slow. A clock near a mass runs slow. The GPS system carries a correction of 38.5 microseconds a day and fails without it; muons created high in the atmosphere reach the ground when they should have decayed on the way; a clock has been measured running slower than another one a millimetre below it. All of that is real and none of it is in dispute. What every one of those measures is a clock — an instrument, made of matter, doing something physical. Whether the instrument changed or time changed is a separate question, and it is memo E.13’s.
And “now” is disputed. Relativity holds that whether two distant events happen together depends on who is asking, and that both answers are correct. If that is right in the way it is usually taken, there is no single present moment and this memo is wrong. That is the strongest argument against everything above. It is memo T.2.2’s, and it is not answered here.
What a clock can and cannot tell you
A clock measures time the way a thermometer measures temperature. It is an instrument, and it can only report on now. No clock has ever gone to the past to check whether it was right.
So the question of what time is may not be answerable by measuring it, and it is worth saying so rather than pretending otherwise. This may not be settled, ever.
What survives is narrow: one present moment, universe wide. That claim touches no measurement. Every result above is about how fast an instrument ticks, and none is about whether there is a single now.
9. What Would Prove This Wrong
- Reaching the past, or the future. Not reading a record of it — arriving at it. If either is a place, it can in principle be gone to. Nothing has ever been found there because nothing has ever been there.
- Finding something that is not in the present. Every object ever examined has been examined now. An exception would end this.
- Establishing that simultaneity is genuinely observer-dependent in the strong sense — that there is no fact of the matter about what is happening now. This is the live one, and memo T.2.2 faces it.
- A demonstration that the passage of time is an illusion which also explains why the illusion is so uniform, so universal, and so sharply directed. The block universe owes this and has not paid it.
10. The Numbers
In summary, the figures behind the argument:
- Arrangements of the universe that exist at any time: one.
- Objects ever found that are not in the present: none.
- Information the observable universe can hold: about 10123 pieces.
- Information needed to record every past moment: about 10151 — short by a factor of 1027.
- Centuries the past-and-future question was argued in the second to seventh centuries: six.
- Traditions on record proposing that “now” differs by place, before 1905: none.
Terms Used Here
| Word | What it means |
|---|---|
| Aether | The proposed substance filling all space: one kind of particle which light would travel through and which matter would be built from. Not an established entity. |
| Deep space | The Aether far from any matter, at its natural density of about 0.9 kg per cubic metre. |
| “Empty space” | A misleading but unavoidable phrase. The space between the stars is not empty. What is genuinely empty is the void — the room the Aether occupies, which has no properties at all. |
Every term used across the series is on the terms page.
11. Sources
Reference codes read source.work.passage and resolve on the Master Source Register, which carries every source used across this series.
- Vasubandhu. Abhidharmakośa-bhāṣya (4th–5th century). The definition of the Sarvāstivāda position on the three times. Carried as reported from secondary sources; the original has not been consulted.
- Nāgārjuna. Mahā-prajñāpāramitā-śāstra (2nd century). The dispute set out directly. Carried as reported; not verified.
- Augustine. Confessions, Book XI (c. 400). The three presents. Carried as reported; not verified against the original.
- On the storage limit in section 3: the bound on information in a region scales with its surface area. Standard in the literature since the 1970s. The arithmetic in section 3 is computed here, not cited.
- T. Bothwell et al. Resolving the gravitational redshift across a millimetre-scale atomic sample, Nature 602 (2022) 420–424. Carried as reported; not verified.
- B. Rossi & D. B. Hall. Variation of the Rate of Decay of Mesotrons with Momentum, Physical Review 59 (1941) 223. The muon result in section 8. Carried as reported; not verified.
Verification register: every reference here is carried as reported from secondary sources and none has been checked against an original. References 1 to 3 are load-bearing for section 6 and should be read before publication — the six-word quotation in particular. The storage arithmetic in section 3 is computed rather than cited.
Ledger — memo T.2
- Derived
- That a complete moment-by-moment record of the past cannot be held inside the universe — about 10123 available against 10151 needed
- That every trace of the past ever examined is a present object, and that knowing about the past therefore requires no past to exist
- Measured
- The information bound for a region, from its surface area
- Clock rate differences with motion and with nearby mass — conceded in section 8, argued in E.13
- Assumed
- That the present is universal. This is the claim of the memo, not a result of it. Nothing here establishes that the present moment extends across the universe rather than being local to each observer, and section 8 says so.
- That contemplative reports are evidence about experience. A reader who holds that introspection is unreliable will discount section 7 entirely, and the memo does not argue against that.
- That the past being unreachable is evidence it does not exist, rather than evidence it is merely inaccessible. These are different claims and the memo does not fully separate them.
- Open
- Simultaneity. If two distant events genuinely have no fact of the matter about happening together, this memo is wrong. The strongest argument against it, and it is not answered anywhere yet — memo T.2.2
- What clocks measure. Whether a moving or low-lying clock records a changed instrument or a changed time. Conceded here; memo E.13
- Whether a record held outside the universe is a coherent idea. Untestable from inside, and this memo takes no position
- Whether “the past does not exist” and “the past cannot be reached” are the same claim. Treated as the same here; they may not be
- Prior art
- Sautrāntika Buddhism, from the 2nd century — the position of this memo, argued and defended for six hundred years. Nothing in sections 1 to 5 is new
- Sarvāstivāda — the opposing position, and the block universe eighteen centuries early
- Augustine (c. 400) — the three presents, which is section 2
- What is added here is only the storage calculation in section 3, and the observation that every tradition assumed a universal present without examining it