This was an interesting read, but to me felt like a focused/narrowed view on very specific phenomena.
If you've ever taken psychedelics, you are familiar with time dilation. In a dose-dependent manner, (external) time ticks slower and slower.
The classic joke is "Two friends are tripping together, one puts on music, and they listen. At the end, one says to the other 'Hey that was great, what album was that?' To which the other replies 'Huh? That was just the first song.'.
It's possible to experience time dilation so intense on psychedelics that external progression of time halts completely and you're sort of "suspended" in a moment in time. (I know it sounds ridiculous and completely impossible)
So I'd be really interested to see research on how it is that psychedelics impact time perception and what the brain activity looks like.
I once had an experience of "time-looping" on acid where I returned to the beginning of the same scene over and over. After four or so rewinds I would say the words of whoever's turn it was to talk before they said it. I'm a pretty rational guy but that experience shook me to the core. There's a Midnight Gospel episode I saw recently that portrayed it in animation dead-on. So I can't be the only one.
Certainly not the only one. I once took too much (only obvious in retrospect) with friends, and the scene replayed what felt like thousands of times. Each time was subtly different than the last, but cumulatively it felt like a whole different world. Eventually I ran into the very difficult dilemma of having to "reconstruct" my original timeline so that I could return safely to it, rather than to the bizarre new timeline we all seemed to occupy. It felt like a Herculean (or maybe Sisyphean) effort to rebuild all of reality to the place where we had left it, but juuust as we managed to do it (seemingly eons later), the trip coincidentally ended. Haven't touched LSD / AL-LAD since.
If I were a materialist, I'd find this hard (but not impossible) to explain. The only permissible explanation would be that the whole thing was an illusion of some sort (insert lots of handwaving), brought on by chemicals in a very real brain. But I'm (roughly) an idealist, and this isn't even the strangest experience I've had on psychedelics, so there's a much broader set of possibilities here -- some of which actually inform my sober life in practical and beneficial ways.
FWIW, I also had the experience/sensation of being "removed" from the standard reality we experience daily, and put into a slightly-altered one that had been "created" or brought on by what was happening. And it felt very clearly like "the rules do not apply here".
This sort of sensation only happened in those particular experiences, all the other ones just felt "normal" (ironic term here).
Look at how absurd all of this sounds when you say it publicly. Psychedelics are something else...
Yes, I've also had very powerful demonstrations of the rules no longer applying. And the more my mind tried to fight it, the more explicit and painstaking the demonstrations became, until I was forced to submit to a shocking realization (roughly: that I do not, and cannot, know what reality "really" is, and shame on me for having the hubris to so confidently insist otherwise).
It would have been very easy for me to ascribe this to something like advanced alien technology, or the simulation hypothesis, or other extraordinarily strange possibilities. From the Buddhist perspective, it is the very nature of mind to demonstrate and teach -- in whatever ways the sentient being requires -- the infinite flexibility and unlimited potential of experience. If one is receptive to it, it can be integrated in a healthy way (much unlike the alien or simulation explanations, IMHO). In my experience, that is why psychedelics are not necessarily appropriate for all people at all times.
Would love to hear more about your story, if you feel like sharing.
> The more my mind tried to fight it, the more explicit and painstaking the demonstrations became, until I was forced to submit to a shocking realization
Exact same experience as well. It was like a Gordian Knot -- the worse I struggled, the tighter it squeezed. It's kind of eerie how similar all the variants of this experience I've read online are.
> Would love to hear more about your story, if you feel like sharing.
Sure. I think it's useful to share things like this so other people don't think they've gone insane/are the only one.
Had a long discussion and went into detail on it before here:
I think it's easier to explain (as a materialist, which I am) if you posit that what has been disrupted is not the real-time sensory and self-awareness functions of the mind,
but those of encoding memory of those experiences,
memory being the necessary stack layer through which this all transpires.
Metaphorically, remember how skipping CDs sound?
Generating and recording the same stream of sound is possible but as you say, "hard," but if the same outcome can through a relatively trivial disruption of a different part of the system...
(I have intentionally made glitch music of various kinds... the fast path is always to force failure modes in the tools, not to try to replicate them through intentional construction :))
To add my own observation of the alternate experience of time on psychedelics: one reason I have loved the 2C family is the recurring perception that the entropic arrow hides from us that all states (T - N, T, and probably T + N) exist eternally all the time; the "we" of any given moment T merely experience it as illusory flow.
As more and more friends die, and other things are lost, it is deeply reassuring to imagine that this might be so–that those people and things are still "there" in a literal real sense, even, nearby in some sense...
...just not one we are privy to given the limits of our embodiment.
Not something I suspect is falsifiable,
but if I'm going to have faith in something, as an aetheist,
When I had ego death, I (if you can use that word) was sort of trapped/floating in space in the universe for an eternity, felt like billions of years. But there was no planets or stars, just a massive void, and my tiny speck of consciousness.
Finally, the void "burst"/exploded and the energy from it caused me to feel "pain" the likes of which I can't even describe. It was like being hit with a laser beam that tore every atom in your being apart.
When I did, I realized it was the birth/creation of the universe, the "Big Bang" (except it's not one bang, it's a never-ending cycle) and I woke up in my bed.
I once experienced existing in multiple points in history as multiple people (no clue who they were) of all ages/ethnicities/gender simultaneously.
The other ones are things that felt related to various religions, except I wasn't aware of what they were until afterwards. But I have never been exposed to religion, and don't have any beliefs.
There are two that stand out to me.
1. I had an experience where my partner at the time, it felt like we were the same being. Two sides of the same coin. This experience wasn't going so well, and I was trapped in bed (not physically restrained, just that I couldn't get myself to move).
And the gist of it was that, I was trapped in time and forced into a choice, and it was to either let myself die and stay there eternally, or create the universe.
The theme was essentially this two-sided entity that wanted to create and then experience the universe to entertain itself, but in doing so would also unleash all the pain that would ever exist.
Later on I wound up running across the concept of the "Demiurge" in Gnosticism, and that aligned pretty nearly with my experience.
2. Nearing ego-death and in my head having the phrase "I am Who I am" repeating endlessly. It had several meanings. "I am", "I am who?" "Who am I?" "I am who I am." At some point I woke up and was speaking some very foreign sounding language that I couldn't stop and I had never heard in my life. I want to write it off as gibberish but the way the sentences flowed grammatically and my voice inflection was not something I could off-my-head improvise in a made up language and sound that natural.
Later found out that phrase has some religious meaning.
Alright, there's most of the batshit crazy stuff you won't believe haha.
One problem is that the further out the experiences get, the less easy they are to put into words (or even into memories). The other problem is that this can sound like bragging or attention-seeking. Nonetheless, as another commenter pointed out, it might be healthy to normalize some of these experiences (insofar as such a thing is possible). In each case, I'm not the only one who has had the experience.
On DMT, I've had the experience of retracting all of reality into a singularity, where I remained for eternity in infinite bliss, until I ("I") was ready to Big Bang the whole thing out again, which I of course dutifully did. As you can imagine, this is a very condensed version of the story.
I've had experiences of discovering how reality is "actually" a dream, and becoming privy to all of the precise, minute details of how everything is projected from the psyche of the Godhead that we all ultimately are.
I've had the experience of living countless lives, from the perspectives of both victims and their perpetrators, until I've seen very precisely why unerring compassion is the only sensible response to anything, ever, period. Why all evil is illusion, and can only be driven out by light (the primordial love that manifests as all of reality). Why humanity suffers so much: because we project the darkness within us outside of ourselves, so that we can avoid taking responsibility. How we wear these projections as a badge of honor: look, we are the good guys, fighting the bad guys!
I have also had more "conventionally strange" trips (if that makes sense) in which physical laws are broken in arbitrarily strange ways. Think of the old Tibetan Buddhist story of a master who was able to fit a large animal (a yak maybe?) into his shoe, without the Yak getting smaller or his shoe getting bigger. Some of these experiences offered me the chance to use all of my normal tools to confirm them as thoroughly as I would be able in sober reality, until I was thoroughly satisfied that no combination of neurotransmitters or standard physics could suffice as an explanation. I would love to share more details, but I'm not sure I can.
I would not blame someone reading this and concluding that I'm batshit crazy. From my perspective, the crazy part is us being so certain we've got reality figured out in the slightest bit. This belief in a fundamentally lifeless reality is the root of so much suffering (for example, the whole climate crisis), and yet we're doubling down on it. It breaks my heart.
My rational mind has even constructed radically skeptical arguments demonstrating why we should not (see my profile, e.g.). Your mileage may vary, of course.
Edit: wow, a lot in common with gavinray's response.
> the old Tibetan Buddhist story of a master who was able to fit a large animal (a yak maybe?) into his shoe, without the Yak getting smaller or his shoe getting bigger
This reminds me of something I once experienced on truffles (the kinds sold in Amsterdam smartshops), but I experienced only mentally. I had this vivid fractal "dream", if you will, of all of reality condensing into a point not dissimilar to the Mandelbrot fractal. When I looked at it, I realized the edges were the limits of human knowledge (or something like that).
But I could go further down or further up, and I realized that I was actually holding this entire fractal in my head, so I could explore any part of it, which meant I had access to all knowledge already.
I realized afterwards that Plato must have experienced the same, promoting his quote that "all learning is remembering".
I also had an experience on 5-MeO-MiPT, when I was tripping and went to get acupuncture. I went to the bathroom before the session started, and somehow I managed to fit into the bathroom despite being so large I could barely get in the door. Very similar to Alice in Wonderland.
I wonder how this size distortion happens, because when I experienced it, it felt so absolutely real.
Nope, same here, twice. I made it worse by opening my phone's stopwatch and starting a timer. The time was in the format 00:00.00, and I could see the milliseconds creeping by, slowing more and more, until the numbers stopped moving entirely and that's the point when I was like "Welp, I made a big mistake here tonight."
Got pretty traumatized from that. You assume linear progression of time to be a given truth of the universe, and when you loop in time or it stops, it's as if gravity had been reversed and you can float now. Cracks the fundamental assumptions you had about everything and you are left trying to put the pieces back together afterwards.
If drugs always wear off in a finite amount of time -- but the drug has subjectively halted YOUR movement of time, you can now logically be in this state for an eternity/infinity. And that's when you get chills down your spine and start to panic haha.
The strangest thing about my DMT time loops was that even though my perception of external time was dragged back and forth, I still have the memory of an internal chronology that was largely present throughout the experience, with gaps here and there
Humans don't remember things so much as we re-create an imaginary scenario based on clues to keep us on track.
So it's entirely possible that your memory--the replay simulation being done right now by your mind without drugs--is what provides the internal chronology, because that's simply how the re-simulation process works.
That’s very possible. Like I said, there are gaps so it’s not an entirely intact chronology.
In the first two or three minutes of the trip (which felt like much longer), I had this perception of “understanding everything” about reality and consciousness. During this time, I was lookin around the room and enjoying the vivid colors that were overlaying everything. Then a very intense and pleasant vibration occurred. After this, I attempted to play Guitar Hero. This only lasted for exactly one note before I started being pulled through the time period of the trip - I felt my perception forced backwards along the exact path that my eyes had initially taken through the room. In this manner, I was pulled forwards and backwards in a sort of loop. I tried to stand up at one point and knocked over a Coke bottle, and I perceived that bottle falling over multiple times. Same for my friend and tripsitter breaking up a post-trip bowl of cannabis. At one point my perception had come to what seemed like the “now” moment and just kinda stopped or got extremely slow. My thoughts went to the idea of whether I was dead and the looping was the experience of death, so I asked “am I dead?” My sitter told me that “you’re more alive than you’ve ever been”. After that, my trajectory through time continued until I felt a similar vibration to the earlier one, except it felt more dreadful. After that subsided, normal “reality” started to fade back in, with me becoming able to tug back against whatever was pulling me through time. It was very surreal. Even once the afterglow faded, my mind was clear for the first time in 20 years. I could think about nothing if I wanted to. Anyone with ADHD will understand how difficult that normally is.
I also experienced this on mushrooms, and found it quite traumatising as well, though I was already (I think) in a bit of a dark place when that part of the trip began, so that probably influenced my perception of it.
> but the drug has subjectively halted YOUR movement of time, you can now logically be in this state for an eternity/infinity
Someone told me the story of a guy that smoked DMT, was out for 15min and when he woke up he said he was never doing it again. He experienced living as a different person for 60 years, having a job, getting married, a whole life.
It reminds me both of the end of the movie Contact and of the game in Blips and Chitz (Rick and Morty).
Did you notice any more obviously physical effects of time dilation then, or just the phone timer? As in, throwing a ball and counting the rotations while it moves through the air, or fan blades spinning, etc?
Just wondering if there's a way to study this as a real measure of reaction-time improvement, versus just a hallucinated one.
I think there are some stimulant properties with psychedelics that I wouldn't be surprised if reaction times were improved. One thing I noticed from my experiences with LSD was that I could run seemingly indefinitely without tiring, and drink quite a lot of beer as if it were water and not feel drunk, when that same dosage while otherwise sober would make me struggle to walk. I think it would be too tough to stay focused on an empirical task to truly measure this, however. My mind might be running quite fast, but is easily distracted in this state.
Historically, Dock Ellis threw a no hitter while tripping on LSD. He could scarcely see the home plate through all the visualizations, but he did it.
I had the same thing on mushrooms once, many years ago. I kept finding myself in the corner of the same room, staring at a troll (an hallucination). It seemed like it had happened a hundred times, and was pretty frightening.
The whole night went horribly, and I never touched shrooms or acid since.
I've had a very similar experience when I was alone, where I sat across from myself on four seats at my kitchen table. I played a game of cards with myself for what felt like an hour, repeating each play from the vantage point of my other selves.
I have absolutely no rational explanation for how I could have imagined this or what phenomena made it take place. The only explanation I can really believe is that I somehow was able to see between the cosmic fabric that separates the multiverses.
I'm confused - are you saying the looping was in perception, or did you believe you actually were? Given you were actively imbibing mind and perception altering chemicals, isn't the easier assumption that your ability to form memories was impaired to the point where the order got jumbled? Your perception is imperfect at the best of time, which we all know, and so what you're experiencing is an at best imperfect representation of what has, is, or will occur.
I am someone who doesn't believe in anything but science and logic.
Let's use Occam's Razor here. Is it more probable that:
A) Time was actually looping or frozen
B) You were on drugs and just confused
I would really, really love to tell you that the answer was "B". But the leap of faith I ask the readers to make is that it was not B, and that it was very real.
I cannot give you a single shred of evidence to support this, nor does it even sound like something other than non-sober delusions and misinterpretation.
The unsatisfying answer is "try it for yourself and tell me what happens."
As long as we're clear that it's unbelievable. Invoking Occam's razor really helps decide it - is it more likely that you are experiencing altered perception while consuming chemicals that are use explicitly to alter perception, or that time itself doesn't follow the rules that are observed and understood and reproducible by some other quality of the perception altering drugs.
I think it’s more that our sober human perception of time and space is a filter we all share and reason about. All clocks tick at more or less the same rate, but a second is meaningless without the “human standard” filter.
Could a third option be that our sober perception of time isn't particularly accurate, and is a construct of our own consciousness? We see a day as a day, but for a fruit fly a day is 1/14 of a lifetime.
Regardless of the rate of time (which we can all experience with doing an enjoyable or boring task), there's no reason to believe the fruit fly experiences time in reverse or as a loop.
I had intense and forceful time loops on DMT. Not just merely perceiving things repeating but literally perceiving being dragged backwards and forwards through time.
Unfortunately, Huberman was frequently cut off and redirected, so he didn't get a chance to fully expound on his ideas. I wish Joe would have just given him the floor in that interview.
He seems oblivious to the fact that his interviews with scientists and other highly intelligent personalities are listened to in their entirety mostly by people who are very curious about the subject matter. His usual stoner meathead schtick - interjecting with nonsense about monkeys, aliens, telepathic communication, etc - really needs to take a backseat.
Lex Fridman is somewhat better though still very imperfect.
Joe Rogan is the force that keeps the interview digestible instead of getting too narrow for most people.
People don't listen to Rogan interviews so that they can expect to understand the whitepaper the scientist published afterwards, they listen for the accessible conversation as if they were just overhearing two strangers meet on the bus seats in front of them. He's a comedian.
Yeah, I occasionally watch some Joe Rogan interview and it's never because of Joe Rogan. Rogan often just lowers the level of discourse with his contributions.
That's intentional (as hombre_fatal points out) but not with quite as derisive an implication as yours.
The point is not for the guest to get super deep into their specific area of expertise for an uninterrupted hour. It's specifically, by design, a conversation with a layman.
Why not? By asking things like that, he gives the experts the chance to address those ideas and present a more informed and/or grounded perspective of them. Honestly I think a lot of the time this is exactly why he asks things like that.
I agree, it's interesting for him to bring up the layperson superficial critiques and other ideas that float around a given subject that many people may not ask outright because of their oftentimes fringey natured questions. But they still wonder about those questions nevertheless. Joe gets all that stuff aired out more or less.
> I wish Joe would have just given him the floor in that interview.
You can't be serious. People don't watch JRE for a scientitic lecture.
If you want a lecture or to dig deeper, go look for it. It's strange how odd people are. They go to a basketball and whine about it not being a football game.
What's next? People are going to whine about how Joe didn't go over Tesla's quarterly financial statement with elon musk?
Both serve a useful function. Some of us might find Joe frustrating, but he's a genial and entertaining interviewer. He's further on the entertainment spectrum than Lex, who is probably a better bet for most of us because we're probably more interested in the content.
That's not a knock against Joe though. The fact he's so entertaining and relatable attracts in a huge audience his interviewees would otherwise never reach, and that's fantastic. OK maybe they don't get to expound their ideas as broadly and deeply, but the fact that they get exposure to so many people at all is a huge win.
Lex's guest list has broadened recently to more closely resemble Joe's, with recent interviews on UFO's and MMA. Which seem like organic interests for Lex but I don't care for when he interviews on these topics
I'm a big fan of Lex, but we have to see that he basically kickstarted his podcasting career by using his MIT cred then made it into a personal thing. Basically it started as the accompanying podcast for the Artificial General Intelligence course at MIT, given by Lex. Given that it's a podcast for an MIT course, he managed to get a very highly esteemed AI guest list, because who would refuse to give an interview as part of MIT lecture materials? In the beginning it had less to do with Lex as a person I think.
With that ex-guest list, he managed to continue after the course as "AI podcast", now not connected to a specific course. But if you tell people this podcast had X and Y top expert in it, you can get many more top people.
Again after some time he rebranded it all under his name as Lex Podcast and is slowly entering culture war territory and is becoming a second Joe Rogan.
I guess he used good tactics, but I'm not sure the initial guests would all agree that their interviews are now part of the Lex-branded podcast.
He started tame and uncontroversial, gained "fuck you money" (his phrasing) and is now using it to spread his broader views.
His interview of his own father is just about the best thing ever.
One surprising reward from my recent addiction to podcasts are the fresh looks at people I thought I knew. Roger Penrose, Malcolm Gladwell, others. So rewarding.
The long dialog format of podcasts is a much welcome relief. Allowing people to finish a thought, the unhurried back & forth.
I recently watched "I Am Not Your Negro" on Netflix. The footage of James Baldwin on programs like Dick Cavett Show is so much like today's podcast. Made me hungry for more.
But I predict there will be a strong backlash against him as he reveals more of his culture war views and how he agrees with Jordan Peterson on some issues etc. I think over the next months many previous guests will disown him.
I've thought about this. Too much. For purposes of this reply, Jordan Peterson will be the exemplar for a self described Rationalists and new atheists (whatever they call themselves) and misc intellectual dark web characters.
My primary criticism is lack of novelty. I've heard it all before. Tell me something new.
A positive example of this, for contrast, is how Ezra Klein is able to have constructive conversations with people he disagrees with. Most recently David French. So I've learned stuff from people I would have never given the time of day. Which reflects poorly on me, I know. But I'm trying to change.
My second criticism is my befuddlement. I just can't figure out what most of the celebrity pundits are saying. I've given Ben Shapiro, Jordan Peterson, and many others more of my time and attention than I care to admit. Because I want to know what others find compelling about their ideas. And mostly I'm just not getting it.
Going in, I thought "Ok, I utterly oppose anything and everything O'Keefe has said and done. He's just a troll in the mold of Lee Atwater. But Eric sounds smart. I'd like to hear O'Keefe describe what he does in his own words." I'm a masochist, I know.
Whatever Eric's criticism of O'Keefe is, I couldn't understand it. I actually listened twice. Because these are smart people, right? Surely I'm missing something.
Alas, Eric's not even wrong. His notions, assumptions, basis for "journalism" are so far off base as to not being worth criticism.
Like a lot of smart people, Eric assumes his obvious competency in areas outside of his own expertise. He's not just willfully ignorant (incurious) of journalism as a profession and it's tortured history, he actively rejects it. So he's doing a drunken sailor's walk thru a problem domain that has already been thoroughly beaten to death by many others with far more intention.
So I learned nothing.
The end result is I now regard Eric as another boring dilettante and don't take him seriously. He's apparently got some heterodox theories about physics, cosmology, or whatever, that might prove interesting. But I'll let people smarter than me chew on those.
--
The thing I most enjoy, savor from Lex's podcast is the novelty, the unexpected learning. I've read Emperor's New Mind and I've read the back and forth about Penrose's theories. So I wasn't expecting anything. But having Penrose himself relate the backstory and his own learning since that book was published made me smile.
Another episode that delighted me was Corecursive's interview of DHH. I really dislike Ruby, right? My study group worked thru a Ruby book, back when RoR was the new hotness. It's not quite the bight on humanity like PHP or JavaScript, but it's pretty bad. Though I was aware of DHH, I didn't know anything about him. I thought, "Well, I like Adam Gordon Bell and if he thinks DHH is work talking to, I'll at least listen for a bit". And I just fucking loved DHH. I want to be DHH. I regret not paying attention to him for all these years. https://corecursive.com/045-david-heinemeier-hansson-softwar...
If he's into a group's approach -- you mentioned Joe Rogan , Jordan Peterson, guess I'll vaguely add Sam Harris, etc. -- and they all make money being independent podcasters, then surely he wants to compete in that space.
Yes, add to that Bret and Eric Weinstein. Essentially he's joining the "intellectual darkweb" as Eric Weinstein calls it.
But I guess the initial big name AI people will be pissed off that they are associated with him, because of gender and race issues.
For example at this point I wouldn't want to share his interviews in an AI related company on informal internal corporate communication channels even if relevant workwise, because Lex will be (or already is) known as "problematic" regarding his broad views.
That sounds like a problem with your company first and foremost. If you ignore useful information from people you dislike, your competitors will innovate faster than you.
I've listened to a number of his recent episodes in full and haven't really heard any culture wars topics addressed. Is this related to his recent episode with Joe Rogan?
"Everyone knows the saying that ‘time flies when you’re having fun. But the full story might be nuanced: Time flies when you’re having more fun than you expected."
Is it such a new concept? I mean if I am just enjoying playing a game, sure I am not so engrossed in the process and might be thrown out of the mood and focus elsewhere. Time does not really appear to be "flying".
I understand the common feelings too have to be checked by science, but if it rings true already, is it a big revealation?
I wonder how the perceptual distortions of time that some psychedelics can cause play in with this hypothesis. Psilocybin mushrooms, in particular, can make time seem to pass incredibly slowly. They do have a tendency to make things more interesting and salient than usual which would tie nicely into the presented hypothesis. Though they could also just directly cause neural fatigue as well. There could also be another mechanism at play.
There is a good paper which gives an overview over the many ways and areas in which a brain perceives time.
TLDR: It is complicated. Tasks like creating synchronized drum-beats use different brain-areas than, for example, estimating whether 10 minutes have elapsed.
> "For example, the estimation of a 1h interval seems to be related to the duration of wake time of an individual, whereas the estimation of seconds and minutes is related to body temperature"
You can use epistemology to reduce any physical concept of the universe to "a concept of the mind, like numbers" by simply stating that we are all humans with minds, therefore anything we conceive or think of is simply a concept in the mind.
Outside of our minds, however, change does occur. Stars spend their fuel, galaxies spawn and migrate, rocks orbit stars in a periodic nature. The English word "time" is obviously a concept, and no matter which human word we use for "time", it's simply one way of measuring these changes we see around us. How can we measure the elapsing period over which we observe all natural phenomenon? That is the second, that is the unit of time.
There's also physics here: space-time. If we think of time as a concept of the mind purely, as you propose, then we also must consider space purely a concept as well, since Einstein proved space-time is a correct notion.
Are those clocks based on actual time or something else like reactions to lighting or number of heartbeats (which probably averages out to the same amount per day)?
There is a base circadian period which is roughly the length of a day, but it varies between individuals. If you put people in caves with no light at all, they'll still naturally fall into a sleep/wake cycle around 24 hours (it tends to be slightly longer).
The answer is it's evolved and some kind of complex cellular feedback mechanism, but Wikipedia is a bit light on details. Apparently this clock is also fanned out in some way to other parts of the brain/body which also follow a daily cycle.
Light isn't mandatory, but the SCN will synchronise to daily light patterns (eg when you travel). The SCN is also physically located close to the optic nerve. I think this is why the underlying rhythm is a slightly longer than a day, because it allows the body to reset it to 24 hours. If the period was shorter, even slightly less than 24 hours, maybe you'd have problems when the clock restarted before the day finished and the error would propagate over time (you'd keep shifting the cycle).
Measuring regular changes in lighting (the day/night cycle) is actual time. (So would be heartbeats, although heartrates vary so much that measuring them would be very inaccurate on a daily scale.)
All definitions and measurements of time rely on counting events that are believed to happen at regular intervals. A second was defined for most of history as 1/246060 of a solar day, in other words, measuring changes in lighting.
I agree but I don't know if that explains how humans can tell time. If you put a human in a completely isolated room with no lighting changes then I doubt they'd be able to count the number of days.
Humans can't tell time accurately without external cues about the day and night cycle. We also can't tell time accurately to the minute if we can see outside but don't know how long the day is, i.e. latitude and time of year.
We can tell time inaccurately by timing somewhat regular internal biological events. That pretty much follows from the definition of time as the interval between regular events (which are assumed for physical reasons to be equally spaced). The only question is which underlying events we use and how.
I think the base circadian day time is about 25 hours, or 24 hours 11 minutes, or similar [1].
I've always wondered what would happen to the sleep cycles of astronauts on long space journeys. They may not have "daylight" to regulate their rhythms.
I am not sure I follow. Time is certainly an extremely important dimension in any complex biological system. The cells do not think about time, but the timing there is very precise too.
Couldn't agree more. The whole system is based on oscillations. It's more robust than literal clockwork, but the balance of systems is dependent upon interconnected oscillators. E.g., a neuron's timing is dependent upon rhythms of vescicle production, which is dependent upon rhythms of mitochondrial transport, which is based on rhythms of kinesin movement...
I'm not often this blunt, but you have no idea what you're talking about here. There are explicit clocking systems both within and across cells and they are very important for regulating many biological processes. Please read this article about how they literally use an analog clock synchronization algorithm (something that has been discussed in the literature for computers, too!) to make sure their internal clocks roughly match the macroscopic clock:
Synchronization does not imply time. It implies synchrony, which is a mechanical notion. Electric signals are used everywhere in life for that purpose.
What they called clocks are not clocks. No more than a frequency generator is a clock.
A frequency generator is the essence of a clock. Why do you think we talk about clock speed in computer science? I'm honestly not sure what other definition you would even use in this context. And certainly, given that these "frequency generators" synchronize, divide time into repeating windows of roughly the same length, and are used to schedule and regulate biological processes, it is a bit bizarre for you to say that they somehow have nothing to do with timing.
What are you on dude? In what universe does synchronization not involve time? Synchronization is defined as "Occur at the same time or rate".
Even if you're so pedantic that you're going to say something like "it could mean rate and not time". Rate also means "the number occurrences in a specific time interval". So how exactly are you contorting your logic to come to this conclusion?
Not saying I agree with GP but there are 2 distinct notions of time. One is related to durations, and the other is absolute time (aka wall time). Clocks measure wall time, not durations. Cellular processes probably don’t care about wall time.
Wall clock time is pretty much only measured in practice as some offset relative to some repeating process, though (e.g. hours since start of day). Cells certainly have processes that repeat on a daily basis, at different offsets from the beginning of the day; they may not actually be measured by counting ticks (the jury's still out on exactly how they do it, I think?), but the effect is similar.
If things happened out of order, the cell wouldn't work at all. There are a lot of different signal pathways that ensure timing is correct. You can take a look at even the most basic functionalities like DNA replication, or energy exchange. And the cell is not timed only in regards to itself, but based on the system it lives in, too - and that system is timed too, repeat x1000000.
Humans (and other living beings) can work with such low amount of waste heat and intake energy only thanks to atomically precise clocking.
Perhaps the above commenter is talking about the perceived scale or speed of time? Order of events certainly seems to matter.
At the same time, order of events is also a certain way of modelling something. There may be alternative models which can be meaningful without the order of time. But most (probably all) models are designed with the way we perceive time in mind.
Maybe watch a video about the process on Youtube? What you're saying is correct in a very abstract sense, but does not really convey what is actually happening inside the cell. Timing is extremely important because if the proteins worked out of order (which is often different based on signals), wrong DNA would come out. Also, other systems inside and outside the cell have influence on the replication (you don't always replicate the whole DNA, sometimes it's necessary to not finish the whole process and do something else as the last step, etc). And replication is not stable at all, btw, but there is very good error handling. And don't get me started on DNA activation.
One more time. DNA replication relies only on particular structures and enzimes to transform these. There is no notion of time whatsoever. Only availability of structural elements, and concentration. Everything is decoupled and feedback loops based.
And sequences of actions are maintained by pipelining of physical molecular structures - each enzime recognizes it's own unique patterns. That is it.
In old times this was called principle-guided science.
Understanding of principles spares one from knowing all the details.
The problem here is that what everyone recognizes as clocks, you don't. The scientific consensus is elsewhere though. There is no reason to call a clocking pathway anything else if its purpose is to determine after how much time should something happen.
I mean, it sounds cool to claim, but if you want to explain to me how a match goes from being a match to being embers without a change over time, I'm all ears.
If you've ever taken psychedelics, you are familiar with time dilation. In a dose-dependent manner, (external) time ticks slower and slower.
The classic joke is "Two friends are tripping together, one puts on music, and they listen. At the end, one says to the other 'Hey that was great, what album was that?' To which the other replies 'Huh? That was just the first song.'.
It's possible to experience time dilation so intense on psychedelics that external progression of time halts completely and you're sort of "suspended" in a moment in time. (I know it sounds ridiculous and completely impossible)
So I'd be really interested to see research on how it is that psychedelics impact time perception and what the brain activity looks like.