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+---- Thread: What Is Time, Really? — Physics vs Experience (/showthread.php?tid=401)
What Is Time, Really? — Physics vs Experience - Leejohnston - 01-08-2026
## What Is Time, Really? — Physics vs Experience
### Introduction
Time is so familiar that we rarely question it — until we do.
We feel it pass.
We measure it with clocks.
We remember the past but not the future.
Yet when physicists try to define **what time actually is**, the answer becomes surprisingly unclear.
Is time:
- a fundamental ingredient of the universe?
- an emergent property of change?
- a psychological construct?
- or something deeper we haven’t fully recognised yet?
This thread explores time from **two perspectives**:
1. **Physical time** — how science models and measures it
2. **Experienced time** — how it feels to exist within it
And most importantly: **why those two don’t line up as neatly as we expect.**
---
### 1. Time in Everyday Experience
In daily life, time feels:
- continuous
- universal
- always flowing forward
We divide it into seconds, minutes, hours — as if it were a smooth river carrying us along.
But this sense of time already hides assumptions:
- that there is a single “now”
- that everyone shares the same present
- that time flows independently of space or matter
Physics challenges *all three*.
---
### 2. Time in Classical Physics
In Newtonian physics, time is:
- absolute
- universal
- identical for all observers
Two clocks anywhere in the universe tick at the same rate, forever.
This picture works extremely well for:
- everyday motion
- engineering
- classical mechanics
But it turns out to be **wrong** at high speeds and strong gravity.
---
### 3. Time in Relativity — Not What You Think
Einstein showed that:
- time is not universal
- time depends on motion and gravity
- different observers experience different rates of time
Key consequences:
- Moving clocks tick more slowly
- Clocks in strong gravity tick more slowly
- There is no single, universal “now”
Time becomes woven together with space into **spacetime**.
This means:
> The universe does not agree on what is happening “right now.”
That alone should make us pause.
---
### 4. The Arrow of Time
Most fundamental physical laws:
- work the same forwards and backwards in time
Yet our experience is directional:
- eggs break, they don’t unbreak
- memories point to the past
- causes precede effects
This direction comes from **entropy** — the tendency of systems to move from ordered to disordered states.
Time’s arrow may not be fundamental at all — it may emerge from statistics.
---
### 5. Time at the Quantum Level
Here things become even stranger.
Some quantum theories:
- treat time as an external parameter
- not as a quantum variable like position or momentum
In attempts to unify quantum mechanics with gravity:
- time sometimes disappears entirely from the equations
- the universe appears “timeless” at a fundamental level
This leads to a profound question:
> If the deepest laws don’t contain time… where does time come from?
---
### 6. Is Time Fundamental or Emergent?
There are two major viewpoints:
**Time is fundamental**
- built into reality at the deepest level
- spacetime is the stage on which physics happens
**Time is emergent**
- arises from change, information, or entropy
- not fundamental, but a useful approximation
At present, physics does not have a final answer.
---
### 7. Why This Matters
Understanding time affects:
- cosmology (the origin and fate of the universe)
- black holes and information
- consciousness and memory
- causality itself
Time is not just another variable — it may be **the key constraint shaping reality**.
---
### Closing Thought
We live *inside* time, which makes it uniquely difficult to study.
We measure it, rely on it, and feel it — yet may not fully understand what it is.
Perhaps time is not something that flows…
Perhaps it is something that **emerges when the universe remembers its past.**
---
**Discussion prompt:**
If time did not exist at the deepest level of reality, what would that mean for cause, choice, and experience?