What is time? The conscious present lasts only a tenth of a second

What is time? The second measures Earth, not time

The question remains open. What is time? And, even more uncomfortably, does the present exist? The starting point is deceptively simple: the second does not measure time, but rather Earth's rotation on its axis. The definition used for precision measurements—9,192,631,770 oscillations of radiation from the cesium-133 isotope—does not describe any underlying reality. It is an agreed-upon rule so that everyone talks about the same thing. The clock, not time. And precisely because the rule works, almost no one stops to ask what is actually being measured.

How long does the present last? About 45 frames per second

The human brain does not perceive reality continuously, although it appears to. As outlined in the thread, it processes images at between 45 and 60 frames per second. A fly, with a much simpler nervous system, connects sight and brain at 240 FPS: that is why hitting it with a swat is almost impossible. To it, the hand moves in slow motion. The same applies to a tennis player returning a serve at over 100 km/h or a driver seeing an oncoming car at 120 km/h.

This conscious present is also tiny. The strip of reality effectively lived lasts approximately one-tenth of a second: what precedes it is already past, and what trinc is future. And it does not always last the same amount of time. The brain works in cycles ranging from 1.3 Hz during sleep to 13.1 Hz in stressful situations. Hence why a boring class feels eternal, while a memorable hour passes in a flash. Age also alters the scale: time seems to stretch when young, but shortens with the years.

The arrow of time: entropy, kaons, and electromagnetism

It is important to separate two questions that are constantly mixed up. One thing is whether time exists; another, very different, is whether the present exists as we imagine it. Regarding the first, the argument defended in the debate is the second law of thermodynamics: entropy always increases, the universe comes from a more ordered state and moves toward a less ordered one. This process is verifiable and provides direction. The asymmetry of the kaon and electromagnetic flow are added to this.

Regarding the second, the answer from modern physics is uncomfortable. Relativity warns that there is no independent time: it only exists in relation to the observer's position and relative velocity. Each observer, strictly speaking, would have their own. It is counterintuitive and the hardest concept to digest.

The non-existent present: from Einstein to Buddhism

From this, more radical interpretations emerge. Some argue that past, present, and future are an illusion of the mind and that the "now" is a construct of the observer. The Buddhist tradition, cited several times, goes along these lines: time as an illusion, just like everything else. One of the classical texts cited states it clearly: time is the moving image of eternity, something to which only "is" applies, never "was" or "will be."

The matter complicates when fiction enters. One of the most repeated theses comes from a science fiction graphic novel: the 0 is the past, the 1 is the future, and the present does not exist. It sounds like a jest, but it coincides with what physics posits regarding events: the instant has no duration.

Can we make decisions if everything is written?

The most useful distinction that emerges is that between predestination and predetermination. If everything already exists and has already peine, there is no margin: pure predestination. If there is a given framework within which decisions are made, the analogy is a river. One can row faster or slower, stick to one bank or the other, but the course and current are not chosen by the rower. Most positions that cross paths in the conversation end up in this middle ground, although almost no one gives up their share of free will.

Why we sleep and what happens when the brain shuts down

On a rotating planet, natural selection specializes diurnal and nocturnal species. Sleep functions as a mini-hibernation: energy economy when there is nothing to hunt. The computer analogy used is that of a shut-down computer: when turned off, everything closes, but when turned on, it loads memory and resumes control. The brain, described in the thread as the most complex object in the universe, would be the extreme case. The counterpoint: that we do not understand something does not make it supernatural, and fossil and genetic evidence explains processes that no intellect grasps all at once.

Why we remain the same

The statistical counterargument deserves a paragraph. It is argued that there is no matrix determining consciousness, but rather probabilities of change, which are extremely low. For the "self" to dissolve, trillions of atoms in the brain would have to be altered simultaneously. It is statistically almost impossible. Hence, one recognizes oneself in the mirror each morning, and not a stranger.

The unsettling fact: a flat universe

And, as a bonus, a detail that breaks the narrative. We work with a model of a curved universe because it works in calculations: it allows us to talk about the Big Bang, the expansion of galaxies, and gravity. But recent measurements place its curvature at zero. That is, the universe would be flat. Fitting this into the rest of the picture remains pending.

This is where the analysis stalls: if the present lasts nothing, if time depends on the observer, and the universe turns out to be flat, it is unclear what exactly we have been trying to measure.