“We live on an island surrounded by a sea of ignorance. As our island of knowledge grows, so does the shore of our ignorance.” ― John Archibald Wheeler

What he says at 3:09 is truly the key.

No physicist in the world today know for sure what "Time" is. However, some youtubers seems to have it all figured out.

I love the way this guy talks. You can see in his eyes that he's not really convinced that what he's saying is in fact the absolute truth, but he's trying to be as honest as he can be given his position of trying to satisfy the interviewers quest for an answer

All I can say is that this man's concept of time is exactly my concept of time and I'm just a guy who's been interested in the time and timekeeping for most of my life and while I do hold an advanced degree, none of my degrees have to do with physics. I came to my view of time by reading and studying on my own. And what is more impressive about Julian Barbour is that he makes his case in plain english.

0:09 What is Time? “A succession of pictures” continuously changing one into the other We need a concept of change to hold a concept of time 0:59 Newton’s flow of time is wrong according to Barbour 2:00 You need change. Without it, you can’t say time has past. 2:58 Watches march in step not with Time, but with each other 3:36 Time, for practical purposes, is about keeping people synchronized, in about the same, common time 4:41 Refinements. Einstein showed the idea of absolute simultaneity is difficult at high speeds 5:24 Simultaneity at separate points. 6:07 We’ve reached a pleatu until Quantam Mechanics. Atoms 6:49 Atomic Clocks, cesium atom. 7:35 Greater Accuracy requires Greater Care, Taking more variables in account

Time is my mom yelling at me for hours

This is a most interesting, thoughtful exposition of "time" as a human construct with innumerable uses in our everyday world. It does not say much about time as the quintessentially mysterious foundation of theoretical physics.

I thought this was going to be the metaphysical interpretation of time, but it's time used as a practical measuring tool type of video.

Amazing! With this one video, millions of physicists were created in the comments section

Even in an unchanging environment or when staring at a picture you have thoughts passing in your mind. As long as you have consciousness You couldn't possibly be unaware of the passing of time. Time is conscious awareness.

Came here after Top5s video to hear about this very interesting !

This week seems like a great use of my time right now.

Time is when you are fed up of waiting for the bus to come on time

I'm a bit surprised with JBs comments about the deep rooted psychological experience of time moving forward and how he experiences it too. I thought with his viewpoint and all the research he's done on the subject that his perceptions would be free of that naivety.

I agree with Julian Barbour's ideas about what time actually is. Time is merely movement in our physical universe. It is wild and unfounded theory which claims that time is a "dimension". I also think that all events are reversible, meaning that time has no true direction. Entropy supposedly is "time's arrow", but with energy or deliberate action (by us), we can reverse "time's arrow". Additionally, entropy must include a change in positions and movement which is the proposed definition of time.

This is it. Time is just the comparison of events with an agreed upon metric (usually a stable oscillator - a pendulum, the vibration of a cesium atom, etc).

Cant see the wind but it's there professor!

Time is our awareness of and sensitivity to the constant and steady flow of energy resulting in the movement of material objects, be they astral bodies, water flowing or clouds blowing. Everything moves. It is the very nature of reality.

I got a idea what it is thanks 🙏🏻

Everyone on the comments had the insight that humanity is trying to understand since always. Amazing how many genius there are on the internet!!

Distance by time is always a constant. The maximum is C. Energy content of anything is the measure of velocity. Directions make senses as for as velocity is concerned. Variations in directions is what traps energy otherwise it is ever constant. Mostly vector equations. Time is a measure of relative velocity of matter to that of light speed.

i'm usually frustrated by videos about time. i think it is a huge mistake to dismiss the most important variable in physics as imaginary :) but this video did not upset me that much :)

Multitasking....on dunny learning about our concept of time.

Astounding insight

This moment, right now, exists, has exited, will exist. In this sense, perhaps, we never truly die.

Time is simply the measurement of change, nothing else! No change, no time...I am a prresentist, the past does not exist as well as the future, only the changes in the present.

I'm addicted to this channel

JUST LIKE HE SAID NOTHING WOULD CHANGE IF TIME NEVER CHANGED.

I like the thinking of that person, Perhaps he has no exception of new idea. I am nobody but as I know time is rule our life more than we think of. Great example is our own body and brain which can communicate more than the tick of clock, even what he thinks about how we get thoughts its about time at it own value.

Time is just a scalar referential and only exist inside us. We created time in order to self-positioning between events.

I found the comments section far more interesting than the video which was lacking in meaningful information.

As a physics professor, the only thing that I truly understand about time is that there is too little of it for me.

I think time can represented as a change in the surroundings which can relate to entropy , if we reverse the changes(both reversible and irreversible)we reverse time.

Superb video, thank you. Time for me is an emergent aspect of Entropy. Without Entropy there would be no way of noticing the passage of Time, and entropy is one directional. Hence, Time is too. Thinking about what i just wrote, i think its not entirely a cogent explanation, since by expending energy, one can undo a high entropy state into a lower one. 😅😅

thank you Julian .

Why TIME fascinates people is the fact WE ALL grow older to the point we DIE as opposed to growing younger towards our mother's womb! We can only experience time going backwards is through photographs or instant replay and rewind on movie cameras.

There is the past, present and future. We call it time. How it relates to the speed of light is quite a jump. The photo ages so it does change.

where is that library it's awesome

I think time passes no matter what, you just need a frame of reference to prove it, just like you need a frame of reference for motion. The earth moves, but not from our frame of reference. Just an opinion, and probably an incomplete one.

he says time hasn't passed because he doesn't see any motion. i think time is moment that passes, even if a glass of water drops and reverses back to how it was, a moment has passed. history has occurred. time travel is impossible but repeat of events is.

It's interesting we're all on time here, just time stamps are different. According to statistical probability, some commentators might pass away since video has appeared. It's like time doesn't pass when nothing is changing on the picture, but inner time order of events that made this section possible is constantly braking down. Picture might appear timeless, but on a cost of it's inner substance also called entropy. This is important because things are in a constant free fall towards center of gravity curvature.

The quote on Einstein not really having given "duration" much thought is a wowser in the context of the clash betw. Einstein and Henri Bergson (then-celebrated philosopher who defined "duration" as the aspect of time that can't be reduced to number), a once-famous conflict recently brought back to light by Jimena Canales' book "The Physicist and the Philosopher." Bergson rules! Einstein drools! XX

"So Man re-created Time again in his own image, in the image of a movie he imagines it..."

Time, Space, Existence, Consciousness, Matter/Energy, Deity, Number... all of these are words (with different contexts and usages) describing distinct but inextricably connected aspects of one fundamental binary: Perceived and Unperceived.

"Time is what prevents everything from happening at once."

Time not only seems to require change in things but also the activity of memory. Without memory, there is no change only disconnected states of things. Another way of looking at this is to say that memory is the glue which holds individual states in an ordered succession of "earlier" and "later". Taking this viewpoint reduces time to a structure in the phenomenal world, the world that all sentient beings experience. I think the philosopher Kant had it right when he said that we must limit our science and knowledge to the phenomenal world. We have no direct access to things as they are in themselves, completely separate from our avenues of experience. Ultimate reality is like the engineer's black box, something whose inner workings we cannot directly experience but only what its output is, given a certain input. To say we can directly experience reality in itself is to say then that reality is phenomenal, constrained and determined by the structure of experience, which includes both time, space, and causality.

BREAKING NEWS: Time is this thing, which can be measured by clocks, so that we can keep appointments. What a literal waste of time...

2:20 - I think to really say "no time is passing," you have to extend the "no change" to everything - the entire universe, including yourself. Even if the whole universe outside of you froze, you still have a subjective internal experience of time passing. You've built that up over from experience. If someone locks you in a dark room for half an hour, you probably know you've been in there for more than 10 minutes and less than an hour. Different people would have more accurate internal clocks. But, if NOTHING changes, universe wide, then I absolutely believe that no time has passed. If you return the entire universe to the state it was in 200 years ago, it IS 200 years ago. Etc.

time is in this moment and recall the past.

spot on. without apparent change or difference, our sense of space and time (or space-time) would necessarily cease. the passage of time is basically translocation (conditions spatially or locally change in relation to each other) or transformation (a condition changes in relation to itself; i.e. the rusting of paint, the melting of an ice cube, or whatever), whereby both translocation and transformation are basically the same thing on different scales or at different magnitudes. a watch and a clock aren't that different from a ruler or measuring stick, except they're usually circular and have a radial arm that mechanically traverses the circumference or regular intervals continually at a consistent speed. however, yes, there are subjective and objective aspects of time; hence 10 minutes of objective time can subjectively feel like an hour of objective time, whereas an hour of objective time can subjectively feel like 10 minutes of objective time. the objective aspect of time pertains to the mechanical rotation of the radial arm around the clock face, whereas the the subjective aspect pertains to your experience of the change or difference that has occurred.

"Time is the interval-laden backdrop upon which marches thermodynamics." - Me

Time has to be defined at a more fundamental level than what is discussed here.

There are four independent sizes or vastness (might not be the correct word, sorry) : Length, Mass, Electrical charge and Time. We have direct observing ability only for the length. Thats why it is very difficult to understand the others. Not only the time.

Hey look, that glowing ball pops up every day, we could use that to make appointments... But..., it's not really a stable system. Don't worry, we'll skip and add days now and then, it's fine. We'll even pull an hour from the bottom and glue it to the top so we have a longer one for a while... My favourite quote by someone in school when i was younger: "it's about time that it's time."

Time is relative only to physical movement. If you believe that what separates future from past is an immeasurably brief moment, then you are seldom present.

Interesting question, but another interesting question is "What is motion?"

I don't know what time is, other than the passing of one's life. In my case, I'm closer to my end than I am to my beginning. So time is not my friend. Maybe that's all time is. The measure of one's life.

Julian Barbour is a world expert on the subject of time; he also holds the minority viewpoint among physicists that time does not exist. He is a deep thinker and this video doesn't do him justice. If you really want to understand his views on time, and learn a lot about the foundations of physics, read his book The End of Time (1999).

Time does not exist. Therefore it cannot begin and it cannot end. What we perceive as time is simply changes that take place in our existence.

Time is a measure of progress. Time has wave properties. Progress through time is directly affected by temperature.

I already agree with that idea but my question is how can explain speed of action s ? If time is an elusion for explain a currency difference between speed of action s how can be explain?

They say time is going from order to disorder but isn't it more accurate to say that time is the measurement of motion or in the case already mentioned, the measure of going from order to disorder, the measurement of change?

I love how everyone who is commenting on these vids thinks they have a clue.

If time is motion then time doesn't exist where no motion is. Motion creates heat - thus when there is no heat then there is no motion and no time. WOOT! My freezer is a time-machine! ^^

I told my physics teacher that time did not exist, that we only experience it because something changes, if nothing changed, we would not perceive it. He send me to the psychologist and I got kicked out of school and they out me on pills. So those pills made me very sad and I never went back to school so I have a very low paying job and I never could get a girlfriend.

Time is a form of measurement, and nothing more.

Time is distance (space) divided by velocity t=s/v. . Frequency is the number of light-waves produced in 1 second of time (f=1/t). Time is therefore the frequency of a light-wave multiplied by its wavelength and it is relative to time (again t=s/v). That is why the speed-of-light (c) in a vacuum just happens to be based on the wave-length and frequency of light-waves. That is spacetime. It has absolutely nothing to do with Earth-time based on the rotation of the earth around the sun, in which time is based on astronomy and not physics.

He is clearly bubbling, Time exists even if we can't persive it.

Universal Time was always a Wild Guess - a simplifying math model based on space.

While there is a general sense of time in quantum field, something does have to happen in space for time to pass in the past, present and future.

His concept is absolutely correct and the reason why time has never been settled on what it actually is, or if it even exists. The issue is just as big taking time out of the equation as having it in the equation. I don't think Einstein agreed with what time was, he just needed to have it added in to complete his theories. The issue is that these theories, which have been shown to be true, over and over again show that time as Einstein thought of it, was indeed real. The worst part which Julian touches on briefly is that Einstein didn't even like time, it was more that he could not exclude it to complete his theories. If you can't exclude time from a working theory then it must be real. The issue with time is that it forces you to comply, it's like a jail you can't break out of. As much as you don't want to include it in your theories, you have to. Even worse is that time makes you comply in theories the same way each time. It's one of the biggest reasons why no traction has been made since Einstein on this subject. The biggest annoyance ever.

Time is a cross-boundary, "unification concept" of motion and he seems to bog down in the notion of time being an agreement between two watches. It's not. Those two watches have to agree with not only each other but with the number of (what we've defined as) seconds there are in a day which has to agree with the speed at which the earth is rotating which has to agree with the speed the earth circles the sun which has to agree with the velocity the sun is revolving around the center of the galaxy, etc.We unify all those different types of measurements with an almost ineffable notion we use as the "master-measurement" and call it time. It IS an "illusion" but a necessary one which is self-imposed. It is, in fact, a requirement of intelligent existence. We literally can not "not have a concept exactly the same as time".

If time is just the measure of change..why does a clock going fast through space click more slowly then a clock at rest?

My idea is Time exists when there's movement in the universe/dimension/reality/existence, call it whatever. If everything stops completely, nothing exists. The light that travels to our eyes to process and "see" things would stop also. How can we measure when all process of perception have completely stopped. How would you explain time to a person that cannot see, hear, or touch anything.

Time is a given frame of reference at a particular point in space.

I’m really fascinated by this, but sadly, I don’t have the Time

Would you take air in and out of lugs while looking in to unmovable picture?

Agree at 1:00 ... because Newton's claim that if nothing happens time still goes on doesn't seem to hold basic water as 'time occurring' would be something. There's no such thing as nothing because it would take something to identify it. So time would then seem to not be a measure OF events but THE EVENT ... events do not 'flow with time' time is, are events ... of if you like, time are the events between events.

My two favorite scientist that i like is Sir Isaac Newton and Albert Einstein

I am here because i want to understand time. Really no one have idea what is time and everybody talk about it

For Mr Barbour the question should not have been " What is time" but " What time is it"?

It is not just the view. Time doesn't exist is reality.

Time is a flow of events....physical or mental ..... The physical seems to offer no reverse direction but strangely, the mind seems to. The parallel universe and time travel is in the dream state .....

Can't we define time as change in the arrangement of atom ?

I trying to understand how the sounds are in real time to reality

Time is a measure of change in the material world.

it's 6:55pm in San Diego

Time is simply the description of change. Change = Time

3.24 Clocks are "marching in steps with each other." Well they are not, are they? Only if they are in the same frames of reference, that is only if they move in unity. Otherwise their steps will not be synchronized.

LOVE ME SOME jULIAN BARBOUR. it took time

We know what time is because we created the construct on the basis of the measurement of movement.

Change α Δx/Δt were the small letter "t" is time. It's kinda' basic physics. I read his book and wasn't convinced. Without time how can you explain the transition from frame to frame? How can you even use the word 'transition' without a time reference? The best you can do is to give time another name, but hell it is still time.

Time is the universe's way of stopping everything happening at once

What might a time separate from causation look like?

Time: a concept invented by man for evaluating the distance between the occurrence of separate events.

I agree with Newtown. Even if nothing is moving. Time Is still ticking

We have the idea of time because of repetition. If there were no repetition/cycle there would be nothing to compare the experience of human consciousness.

What really exists in this reality is "events" not "time". Events have their own pace ...slow, medium & fast .Time is only a "measure" of "pace"of these events happening. In reality, the pace of an event can be increased or decreased by means of some force.....so.... Time is only a "measure" associated with events. Got it?

To sum it up its all great sounding theories, but thats all they are. We like to hear these scientists talk because it gives us the idea that we as humans understand exactly why we are here. Maybe to cope with inevitable death? Finding peace in scientists that do the thinking for us, so we don't have to think for ourselves? What if there was a creator, and this creator wants to give love and understanding, but we reject it by listening to these prophets? Maybe we should repend and listen to our heart, why do we have these morals, why do we know what is bad. Why do most humans just want to attract a partner and create a family, I mean in the core of what we want. You can argue career is important, and a lot of people think they want that, maybe through TV shows and celebs telling you that getting to where they are is the answer. To build a career, to make a name for yourself, for what? Where do you live for then? Money? Power? Ego? We know money does not create positive substance in the mind, fame doesn't either it seems, if you take a close look at them. Who is creating these celebs? And why? I would argue maybe its like the lottery, once a year some one wins it, thats enough motivation for a lot of people getting a ticket. Maybe it's the exact same thing with actors and fame, they are the lottery winners of fame and fortune, showing how it is possible for young people to pursuit these empty goals. Maybe this is one of the many parts that is destroying people, depression, suicide, it's the biggest killer ever, yet nobody talks about it; here, take a pill, created by scientists in a lab serving big pharma. End of bad spelled rant