Does Time Exist? | Hacker News Reader

Does Time Exist?

bigthink.com

49 pointspseudolus67 comments

Time doesn't exist as an independent physical objective entity, it exists only as a measurement. Sometimes we represent that measurement with physical objects, such as with clocks or watches or in our heads (I can hold my breath for N seconds). It's no different than your height existing as a measurement, or the distance from here to the wall existing a measurement, or the distance of 10 meters existing. There are physical entities that exist within the measured space of course, the measurement entity as such does not exist (only in your head, or similar (eg in a computer), as a calculation). It's also the same as three apples and three oranges sitting on the table, and you multiply them to get the number nine - there is no new independent physical entity of nine objects created, other than the calculation as represented temporarily in your brain space (ie you're not able to manifest new tangible entities into physical reality this way, you can merely calculate and store the count as a computer by rearrangement).

This is also why time travel backwards can't happen. There is no back there to go to, there is no saved record that some omnipotent entity is keeping track of. Backwards time travel requires either a fantasy premise of time (the mistaken notion that time is a separate, independent, physical thing and not a measurement), and or a god-like creature that has infinite energy to record the location of every unit of matter at every unit of time along with the ability to reassemble all of existence back to each save point - it gets comically silly fast for a rational person, you're better off believing in ghosts and the easter bunny.

That's certainly one view of time. Relativity views all time as existing "simultaneously"; the block universe. The past exists along with the future. The passage of time is then just an illusion seen from within the greater whole.

I prefer a view of time closer to yours I think, where there is a single moment of existence, the now, that evolves.

For more on this topic, I recommend Carlo Rovelli's The Order of Time. The book is very accessible to non-experts in the field (like me), and it opened my eyes to some super interesting and unintuitive ideas about time.

I’ve been wondering a lot lately if it’s possible that time is felt differently (I guess moves) for us on an individual level.

I think about this a lot too but I think it just has to do with the way memories are stored in the brain - not anything to do with time itself.

It's sorta handwavey but I've seen it explained that at age 40 a year represented 2.5% of your life while at age 10 2.5% of your life (especially your post baby life) may only be a few months.

And to put it in terms of some advice I do think time moves differently depending on how much new memories you are taking in. Vacations to me can seem to be very long while weeks where I settled into my normal routine flew by.

As I approach 40, a year feels about as long as a month did when I was elementary-school aged. I worry that if the current rate-of-increase continues, my last decade will feel weeks long.

I think the answer to this is to do more interesting things on a regular basis. If every weekend you do something different, then the month feels longer than when you stay home every weekend.

I've long been skeptical of this explanation. Later school ages (junior high and high school) were probably the most monotonous and regimented part of my life, period—I've certainly never experienced that much concentrated, intense boredom without any way to do anything about it—yet subjective time had only barely sped up from elementary school. It should then have slowed way down in college, but it didn't. It should have slowed down again a ton when I had kids, but it didn't. The change has been consistently in one direction, as has the acceleration of the effect.

I’m less interested in how long it feels in my memories, and more in how long it feels while I’m living it. If it makes any sense, the question is how to cram as much—consciousness, I guess?—as possible, into however many decades I get.

That’s the rub, isn’t it? So many people are focused on every other moment besides “now”. Memories build from our past, and they’re constantly appearing in our minds based on various stimuli. Moreover, society is structured in such a way that people are constantly focused on the future. It’s very difficult to actively live “in the now” and focus on the actual experience of simply existing.

That’s really the biggest tragedy of modern human existence, many people never get to see the true beauty of living in the now, they only get to see it from the “bad” perspective, when their negative emotions become overwhelming and time seems to slow down to a standstill.

Normalize living in the now. Normalize the idea that our “purpose” on this Earth is simply to exist, and that “purpose” can be the most important of all possible purposes.

To quote the ever-wise Ferris Bueller, “Life moves pretty fast. If you don’t stop and look around once in a while, you could miss it.”

I've had a pretty opposite experience. The busier I am, the more I have to process, and time feels to pass more slowly. I feel like the first 6 months of my kids life took at least twice that.

Saw someone wearing this T-shirt at a 10k race:

"Life is short. Running makes it seem longer."

Great advise! I wanted to add a bit more to it. As you age the number of novel experiences and "space" for those experiences in your brain decreases. So the first 20 years of your life you accumulated a lot of new experiences while your brain was growing an expanding. For this reason it feels like you lived in regular time. Your final 20 years will mostly be nothing new and what is new will largely include a base that is shared based on past experiences. This is why as you get older time moves faster.

I feel the same way about my time in elementary school. My theory is that it was boredom that made school time feel so slow. Summer vacation always seemed to fly by.

Time is felt differently at different points in our life, even within an individual’s experience. When you pay more attention to the passage of time itself, it appears to elapse more slowly. When you don’t pay attention, it appears to elapse more quickly.

Yes, I would absolutely accept that we all perceive time at different rates, but where we externally synchronize with measured “seconds”, we don’t have any way to communicate that my “second” may subjectively feel longer than your “second”. Similar to how we can’t really describe what “red” looks like to someone else, without using the word “red”.

I think someone has proposed a formula according to which we experience the passage of time as a function of age. So basically time passes faster the older we get, I guess the reason would be that there's less and less fundamentally new things to experience and hence less lasting memories. I saw it in a numberphile video, but don't remember which one unfortunately.

To me it's pretty intuitive that time isn't real (outside of being a concept). We just use time as an elaborate way to explain our movement through distances (and how fast or slow we cover those distances), that's about it. The twin paradox[1] does a good job of explaining this.

There's no discernable difference between today and lets say, arbitrarily, 1984. The only difference is our movement through that spatial distance.

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

In your rebuttal, you used a concept that necessarily assumes time ("how fast or slow", i.e. speed) to argue against the existence of time?

Velocity is real, distance is real, time is how we've decided to describe their relation.

Physically and philosophically, the "idea of time" isn't real. It just helps us describe our reality.

velocity is defined as distance over unit time so I’m not sure how you square that circle

Semantics but velocity being a measurement of somethings movement through a distance is exactly what I'm saying time is. I've stated that we use time to describe stuff, like velocity. But "time" as a physical property like gravity does not exist.

You could probably replace the usage of "time" with "increase in entropy", but it just makes it harder to understand WRT velocity. As your velocity increases, the entropy in the universe has increased as a result of whatever mechanism for acceleration is being used. If it's gas, then you are going from a nice, mostly orderly/low entropy liquid in a container, to a chaotic, high entropy gas that's now in the atmosphere.

Given that the speed of light directly relates time and distance in (to the best of our extremely precise measurements to date) an absolute manner, then if time doesn't exist, neither does distance.

Also, as TFA mentions any dismissal of time as a concept must also deal with thermodynamics.

here is another way of looking at it: the speed of light actually shows us the maximum speed of causality (how fast can a change in point A in space propagate). Some might speculate that the same speed of causality is observed in everything, it just so happens that most transformation happen in place giving us the illusion that we are stationary in space.

The speed of light is still just the movement of something over a measured distance.

I can flip that around and say that a distance is just the movement of something over a measured time. By your original argument, distance doesn't exist.

I get what you're saying. But the physicality of a distance seems more meaningful than our movement through that distance.

I've tried articulating this idea before but its very cumbersome: You want to go make a drink in the kitchen, the difference between the future you making that drink and right now is only your movement to get to that point. You making the drink and you not making the drink are exactly the same "points in time". But for perception, you making the drink is an idea you see as a future event as opposed to a concurrent event that involved some movement through a distance.

Given distance, velocity and time; choose any two as physical and the third will be emergent. Choose according to the view you want to explore.

The fact that the third is emergent seems to me like more evidence that it is real, rather than the opposite

c is the render speed of god's GPU

When I was younger I imagined in my head that a specific moment in time is literally just all of the information about the observable universe -- the position, momentum, temperature, etc of all of the particles in existence relative to one another. I’m running on very little sleep right now so be prepared for a little woo here; I’m expecting someone smarter to come correct some misconceptions in my take and hoping to learn a little bit from that.

For me, that idea always been enough to get by (without existential questions), albeit it's a little bit different from the three-axis-plus-time description in the article. It explains really intuitively why reverse time travel isn't possible (non-reversible reactions, energy required to reverse the entire universe into a previous state, etc). It also makes it intuitive that time does exist, since "time" is a noun referring to the overall state of the universe - a specific state in a set of states that at least appears to progress sequentially... but perhaps does not. Actually, looking at the questions in the article, it seems to jump out that time is uncountably infinite (since "absolute time" cannot exist). Even so, the “arrow” of time would be evident from within any of these states because there is only one direction that certain starting conditions can lead. “Time” does not account for parts of the universe in isolation, but rather all of it as a whole - so there are always plenty of pointers.

Edit: This seems to be a naive/flawed way of understanding canjobear's statement: > Time is the direction in which entropy always increases. It's the most real thing there is.

I want to rephrase to, "if time doesn't exist, how do we know where things are?" or "if time doesn't exist, how do things move?" - which seem to get back to the 3-axes-plus-time description.

Agreed! In my mind, to go back in time is to put all particles or whatever fundamental components back in the same place and state as they were previously. Thus, that would include the particles that make up you as well. How would you ever do that and if you did, how would you notice and is it really the past or just now with a replicated state?

perhaps if there is order to the expansion of the universe and all its things you could contract it and theoretically cause all particles to shift back to their older states. i guess noticing is dependant on how much our consciousness is coupled to the physical

I have no clue about the science but I like to think of time as an illusion, just for the fun of it. It appears to me to be our way of making sense of reality based on our limited senses of what's really going on. There is only "now" in reality - and we can't begin to imagine what that is like - so our minds layer up moment after moment to create the illusion of time. Previous moments are our memories, right now is reality and future moments are our imagination.

If we didn't have the ability to "layer up" moments in our minds, we probably wouldn't be able to make sense of music or speech for example.

Reminds me of my favourite film Memento. If the protagonist forgot everything every nanosecond instead of every 10-30 minutes or so, he would probably be completely in touch with reality and have no concept (or illusion) of time. If you put two Leonard Shelby's in a room and lock the door and observe what happens, they will eventually bump into each other but only from the observer's perspective (his mind observing the layering of moments). Neither Shelby will be aware of how many times they have bumped into each other or what "bumping into someone" is like (because even something as small as bumping into another person is hundreds of little moments layered together in the mind).

afaict, "time" is simply a measure of matter in motion... ie resonant frequency or how long it takes a liquid to flow x distance. Thus, time is just a mental construct, not a "dimension", and "time travel" is not possible. There is only "now".

Unless all "times" exist at every "moment" and we are merely switching consciousness between those. Maybe we are not even switching, because by "going backwards" we would be losing memories and would not know, that we went backwards. Same goes for forwards. It only seems forward, because our memories change that way. Maybe we are all just coping, trying to make any sense of every state, future, past, present, existing "all the time".

My DMT “time loop” experience makes this whole topic extremely fascinating to me. I very clearly (to me, within my own subjective experience) witnessed some of the exact same events happen multiple times (within the timeframe of the experience, anyway). It was like there were two separate chronologies existing simultaneously - that of my subjective experience (the “observer”, if you will) and that of the perception of my reality.

Time exists in the similar sense that rivers exist. If you look too closely the thing fades away into individual water molecules. But when you zoom out it's not a rain drop or a cloud or fog, it's a river.

I'll ask another one: Does it matter, whether time exists? If we go with the idea, that time merely describes a number state changes of the universe, then it might not matter, whether time actually exists.

If time doesn't exist, then... does space exist? If space exists, does motion exist?

It's pretty clear that things exist in different places, that things move, and that for certain events, there is a "before" and an "after". It's really hard to take those seriously and still say that time doesn't exist.

Perhaps a more interesting question is, which time exists? There's (at least so far) a rather fundamental difference between time in general relativity and time in quantum mechanics. If time exists, which time is it that exists?

I dont have time to read the article. do I exist?

the question is: does the article exist if you don’t read it?

One of favourite videos ever on the internet is a 'science slam' video about the thermodynamic nature of time (and entropy) from about a decade ago. It's in German but the auto-translate does a good job.

https://youtu.be/z64PJwXy--8

Obligatory Alain Connes post:

http://noncommutativegeometry.blogspot.com/2007/03/time.html

Asking about time gets you into adjacent issues like free will. I find that interviews with Lee Smolin are illuminating, even tho I'm totally OTL on the technical aspects.

Yeah, time is our tracking of the evolution of processes, and it can't go backwards but sideways like in Thomson's Lamp.

It cannot. For it to exist, it will have to occupy itself.

when all matter turns to EM radiation, at the end of the universe (arguendo), then time will cease to be measurable, and so will distance.

> Does Time Exist?

Only relative to a given frame of reference.

Time is the direction in which entropy always increases. It's the most real thing there is.

Or at least tends to increase. Entropy can always spontaneously decrease, or can simply not increase for a moment. This was actually discussed a week ago! [1] As discussed in those comments, entropy isn't well-formulated outside of equilibrium states, and is subjective: it is a function of an observer's knowledge of the system (particularly microstates).

I'd say time is very real, and an inescapable part of experience (no experience without change). As for time being the most real, we only know it through experience, so I think of it as secondary, along with space, etc.

[1]: https://news.ycombinator.com/item?id=31164725

In my—undergraduate, not-very-specialist—days of being taught something or other about entropy now and then, I felt like we were being told "This state is special, so the entropy is low, and then it probably ends up in one of these other states, and none of them are special, so the entropy has increased”, and it would seem to me that we could appreciate all of the states as equally special if we were big-brained enough. Maybe like the integers being Ramanujan’s personal friends.

Yes, good book on that is The Order of Time, for anyone who hasn’t read it.

https://www.goodreads.com/book/show/36442813-the-order-of-ti...

does entropy always increase? are there systems or forms of matter that literally cheat entropy?

Any system can cheat entropy as long as it's not a closed system, by decreasing locally but increasing it globally. Life is a good example.

life and information are good examples, yes.

i sometimes wonder if our understanding of physics is somewhat limited to what we can see/observe/measure (include instruments here) and wonder if the laws of physics as we perceive them are only a set of laws that are not necessarily universal and apply anywhere where matter exists (that a long way of saying that maybe entropy comes with only one set of laws of physics that just so happens to be the ones that we are experiencing right now)

A plant is what a seed does to the dirt around it.

It exists in the way weight or distance exists.

what if time is caused by movement? relative time, since we already know spacetime to be an entity

A great man once said, "Time is an Illusion...Lunchtime, doubly so."

Sounds like a deep quote I read from that page in Reader's Digest.

If that page was authored by Douglas Adams then yes that’s where you read it.

I was making a reference the next line in the book:

"Very deep," said Arthur, "you should send that in to the Reader's Digest. They've got a page for people like you."

(How embarrassing.)

Eh, it's one thing to know a highly memorable quote. It's another to remember the following line.

I've listened to the audiobooks of that series so many times.

Tangent, they got Simon Jones to read for book 6. which i thought was a mistake. He played Arthur in he radio dramas. It made the audiobook hard to follow because every character sounded like Authur.

Obviously no time to find another reader.

Didn't the great @jaden once say, "How Can Mirrors Be Real If Our Eyes Aren't Real"?

Reply on news.ycombinator.com