The closer we look at time, the stranger it gets

[thom]

All of this should be familiar to the average programmer. The Creator (I call him Colin), rushed for time and bereft of more elegant ideas, has widely deployed lazy loading as a solution to the finite processing power of the universe. Almost all of physics (the speed of light, the expansion of space, quantum entanglement) is an answer to the question of how the universe (and indeed Colin himself) can avoid doing too much work.

[ndsipa_pomu]

I bet Colin gets annoyed every time we point a telescope at far away objects as he has to rush around behind the scenes and paint in all the details.

[jesuslop]

he sends the electron both slits so is also doing some complex-numbers montecarloing. Since he has infinite ram he can sum every-single-path.

[ChuckMcM]

This was perhaps my favorite part of Physics 390 ("modern physics") which was about quantum dynamics and relativity. The speed of light is defined in terms of a velocity (~300,000,000 m/s) but if you were traveling at the speed of light time stops (which keeps the rule that its constant in all frames of reference). That and time passes more quickly at higher altitudes and these days we can actually measure that. Wild stuff.

[MaxikCZ]

The fact that at speed of light time stops is just so bonkers to me.

A photon is, from its point of reference, at the point of creation and at the point of destination at the same "time". Its literally seeing both parts of the universe at the same time, and since its traveled some distance over that time it cannot perceive, its essentially connecting 2 points in spacetime.

If I understand it correctly, every photon exists, from its point of view, for only infinitely small amount of time (similar to how virtual particles do exist from our point of reference), but for us its so easy to "play" with the photon along its path, giving us plenty of time to even decide what we want to do with it after it has already been created.

Its just so bonkers that time can be perceived such differently depending on frame of reference.

[euroderf]

> but if you were traveling at the speed of light, time stops

Are we saying then that it is theoretically possible that (a) photons have a zero or near-zero lifetime, but that also (in our frame of reference) (b) they exist for a finite duration of time and are visible during that time simply because time stops for them ? Or did someone manage to slow down light to some fraction of light speed ?

[tacker2000]

Also see the twin paradox, which is related to this and equally fascinating.

If one twin stays on earth and the other makes an intergalactic trip (with the speed of light), upon return, the one on earth will have aged much more than the one on the trip.

[gilbetron]

My favorite explanation: https://www.youtube.com/watch?v=Vitf8YaVXhc

[tornikeo]

Not related to this article, but this post seems to attract so many cranks. Just look at other comments. The amount of weird (out-of-touch) comments on this post is fascinating.

[f3b5]

Some of those might be AI accounts that found an ambiguous topic for upvote farming.

[sbuttgereit]

I think I like Tim Maudlin's approach to the question. Time isn't all that mysterious: it's simply fundamental meaning it cannot be explained has being the sum of some things more fundamental. The argument is that's where the difficulty lies for many is they want to express time as though it's a composite, and it just isn't. So the best you can do is explain time by referencing those other aspects of existence which incorporate time.

Here's a much longer take from Tim Maudlin, "Tim Maudlin: A Masterclass on the Philosophy of Time" (https://youtu.be/3riyyEmWwoY?si=9aI-bETWcNpdjMW9), Tim Maudlin is Professor of Philosophy at NYU and Founder and Director of the John Bell Institute for the Foundations of Physics. The podcast is Robinson Erhardt's.

[grebc]

I like Tim, his arguments come across as an honest attempt to answer real questions. I feel as if the current crop of physicists look down on things that appear too simplistic.

Their math give an answer with artefacts they can’t match to reality so they keep probing the outliers of these absolutely bonkers ideas, and rabbit holes keep getting deeper & weirder.

Time doesn’t exist. Do the people writing this garbage live in a vacuum? Is it AI slop?

[finghin]

SEP is always an interesting companion to these articles about physical fundamentals. [0]

[0] https://plato.stanford.edu/entries/time/

[rausr]

I'm only slightly disappointed that this is not the "Someone Else's Problem" version of SEP.

[My_Name]

They nearly have it in the article but don't take the next step, which is to realise that time is gravity. We are falling towards the future at the speed of causality. You can slow your experience of that by travelling really fast, or by being near something with a large gravity. Quantum particles can simply ignore gravity and time while we are forced to feel their effects due to our size, like a mote of dust can ignore gravity, but a brick can't.

[benchly]

You might be interested in The Order of Time by Carlo Ravelli. Time and gravity are certainly linked, but from what I took away from the book (which is a lot to digest, even as non-mathy as it tries to be) is that Time is really heat. Heat moves only from hot to cold, dispersing in some entropic fashion as we move toward the final state of the universe, but in the meantime we can measure that time/heat "flows" at different rates, depending on how near or far you are from large bodies.

I likely need to reread it, though, as some of its ideas are a bit above my weight class when it comes to understanding physics. But, you may enjoy it!

[sigmoid10]

Well, almost. Because these usual descriptions you give here are approximations. Yes, to the first order, gravity is expressed as the effect on time in general relativity. So you could describe how planets move simply by calculating how they move differently through time. But in the full picture, the way you move through space or near strong gravitational fields also influences your experience of space itself. So the ultimate realization is that gravity is space and time. Or spacetime. Basically exactly what the article says when it references general relativity. And it holds as well for quantum particles. They experience spacetime just as well as we do. The ultimate question is, does spacetime itself also come quantized when you look close enough? This is the true head banging one that noone knows.

[throwaway77385]

A mote of dust doesn't ignore gravity in a vacuum ;)

[slyfox125]

We understand "time" in the context that we must: to subsist in order to procreate. The extent it exists outside of our own perception as we imagine it does, is debatable. Ultimately, time is our sensory interpretation of the world around us to facilitate our survival and thus, we may never make sense of it outside the constraints it exists within.

[ricardobeat]

We know empirically that time only flows in one direction, it can’t be described as just a perception. You’d have had at least the tiniest of evidence that time sometimes flows backwards.

[robot-wrangler]

IANACosmologist, but in for a penny, in for a pound. If one accepts weirdness along the lines of extra spatial dimensions and mathematical singularities made physical, why not throw in a few extra dimensions for time or why not have imaginary time (in Hawking's sense)?

> One might think this means that imaginary numbers are just a mathematical game having nothing to do with the real world. From the viewpoint of positivist philosophy, however, one cannot determine what is real. All one can do is find which mathematical models describe the universe we live in. [1]

[1] https://en.wikipedia.org/wiki/Imaginary_time

[actionfromafar]

"describe our observations of the universe"

[netfortius]

I strongly recommend reading Carlo Rovelli, starting with "The Order of Time"

[ndsipa_pomu]

One problem that I have with trying to understand "time" is that we can't measure how quickly it "flows" or at least how quickly we travel through it.

[skissane]

> One problem that I have with trying to understand "time" is that we can't measure how quickly it "flows" or at least how quickly we travel through it.

Our experience of time passing is heavily influenced by the temporal granuality of our subjective experience-at the upper end, “now” lasts 2-3 seconds; at the lower end, our temporal discrimination goes down to tens of milliseconds for visual and tactile stimuli, and reaches down to microseconds for certain types of auditory stimuli. But, one supposes other species with different neurology would have these durations be shorter or longer, which would make time pass more slowly or faster for them, in subjective terms.

[ben_w]

> we can't measure how quickly it "flows" or at least how quickly we travel through it.

I don't understand this, because it seems like "with a clock" is too obvious an answer, so surely you can't have meant what it sounds like it meant?

[sbuttgereit]

I guess I have to ask what more you're looking for, perhaps hoping for, than: 1 second per second?

[msuniverse2026]

In Anthroposophy or Western occult science time runs in reverse in something we call the etheric body. The physical body on the other hand is something that experiences the world through organs that register only the present moment. It can't perceive what no longer physically exists or what has not yet manifested physically. The etheric is a time-body, containing the complete formative record of one's biography and is the source of memory, the brain is sort of a receiving organ for it, though the whole body utilises it.

Upon death the etheric body opens up and turns itself inside out and as you identify less with your physical body and more with your etheric body your perception of time is now in reverse. Your entire life tableau is opened in front of you, and as your spiritual organs of perception once "facing inwards" to your interior are now "outward-facing" and working backwards you start to see the effects of all your choices and actions from the perspective of its consequences. This is the source of those "life flashes before your eyes" moments people with near death experiences go through.

Only for very unconscious people is it a hell-like experience. Even if you lived a rather thoughtless and abusive life it is said that it can still be a time of reflection and learning. Eventually after viewing your entire life "inside out" your perception opens up to your pre-birth condition, the etheric body sloughs off (being made of elemental beings itself) and is picked up and put together with all the karma of your previous lives for your next go-around on Earth. You liberate the elementals in your etheric body (which are just below humans in the spiritual hierarchy) by growing spiritually either during life or in the etheric condition and eventually, hopefully, move up the spiritual hierarchy to a being that liberates humans, an Angel.

Thought maybe HN might be interested in some other conceptions of time. :^)

[juleiie]

Interesting that this comment appeared precisely when I needed and wanted to see it on the most unlikely of websites.

Thanks for your insights

[hikingsimulator]

Given how "western occult science" is just magical thinking and pseudo babble, it hardly fits on HN. Additionally, "western occult science" typically glosses over its 1920-1940s roots and branches. Wondering why...

[user3939382]

I have a solution that addresses this. Will publish soon, it’s a slow process.

[IAmBroom]

Ooh, do the unified-field thing next!

[Antibabelic]

Would you like to share any details?

[nrhrjrjrjtntbt]

Bad for the BBC brand to have this site licensed which is riddled with ads. Turning off JS does the trick though.

[euroderf]

I've read that cats can remember the future. Let's see someone fit _that_ into their theories.

[IAmBroom]

Yes, the internet is full of BS. Good for you for reading!

[zkmon]

What's new here? I spent a few minutes reading it end to end, and it sounds like slop without new info.

[grishka]

There's another inscrutable mystery in physics, the nature of consciousness. Time might as well be an artifact of that. I'm surprised this article doesn't mention this possibility.

Here's an interesting lecture about it: https://www.youtube.com/watch?v=YusrOYGAhqM

[IAmBroom]

The first problem with the nature of consciousness is describing what you mean by it. Try, and I guarantee you that someone will find a sponge, Apple product, or bathroom slipper that meets that definition.

Electro-magnetic radiation, on the other hands, is highly describable in precise, testable, repeatable terms.

When you can state Maxwell's Laws of Consciousness, we'll talk. And rename them "Grishka's".

[euroderf]

> consciousness. Time might as well be an artifact of that.

Psychedelics can remove the sensation of time passing. But they are also modifying the experience of "consciousness" itself.

[drcongo]

I got downvoted on here not so long ago for mentioning time as an emergent property of quantum consciousness so maybe it's controversial.

[juleiie]

Can anyone actually understand this at this point?

I will reread it like three times maybe the third time is the charm

[anal_reactor]

The ads on this website are atrocious.

[amanaplanacanal]

I recommend an ad blocker. I didn't see any ads.

[dotancohen]

  > Combining quantum mechanics and General Relativity is all well and good, but there‘s one key mystery it doesn’t address: why does time only seem to flow in one direction?

Could the problem just be with us? When time flows backwards, we lose the ability to perceive the events that came after the "current" event. As it flows forward again, we have more time in our context window. We are able to perceive only those events that have occurred before the current event.

Time still flows and ebbs, we just lack the ability to sense it just like a cork in a river doesn't feel the water flowing past.

[russdill]

For the "canonical" physics explanation, see:

https://en.wikipedia.org/wiki/Past_hypothesis

You can happily run physics backwards and forwards, and there's no difference. But assuming that entropy was very low in the distant past is very useful and lets us talk about fascinating things, like what happened last tuesday (or 12 billion years ago)

If you just know the current state of the a system, there isn't really any difference between running time backwards and forwards. Of course, if you know exactly the state of every particle, field, etc, and the past hypothesis is true, running time one way will lead to lowering entropy, and the other way will lead to raising entropy. But if you're a mere mortal and just know the macrostate, either way you run time, the entropy of the system will increase.

[hnfong]

there is no flow per se, as it’s a subjective experience. it’s just that our current environment (specifically human environment) is predominantly structured in a way that the past makes an imprint on the present (in terms of biological memory, historical records, etc) and the future generally being unpredictable because we kinda don’t want it to be too predictable (eg you don’t want to be too predictable when a tiger is chasing you for example)

but in other environments (talking about same universe here!) the future is more predictable than here on earth, for example motions of planetary bodies can be predicted way in advance within error bars as in the past, and when you have that kind of relatively symmetrical system, any subjective experiences within those systems would be much less inclined to feel that time flows on way or the other. (of course, the only kind of subjective experiencers we know are made of biological stuff which structurally remembers the past and leaves the future open as form of evolved ability, so this timelessness experience may be harder to imagine for us)