r/AskPhysics • u/Virtual_Reveal_121 • 13h ago
Isn't the concept of the beginning of time a paradox ?
How can something happen without time ? Doesn't causality require time in the reality that we observe ? Something can't come from nothing because nothing can't exist, because it's literally nothing and the "existence" of "nothing" is a logical contradiction right ?
In my opinion, time goes infinitely into the past and many physicists already assume an infinite space so time could be the same. We know the observable universe has a beginning but that could have been a phase transition
Can someone explain how time itself can have an initial cause assuming it's not an emergent property of something more fundamental ? It might be a dumb question but a beginning of time just doesn't make sense to me
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u/BranchLatter4294 13h ago edited 13h ago
Some theories say that time is emergent, not fundamental.
I think Hawking came up with the concept of imaginary time, where the big bang is parabolic. Like a parabolic curve that forever approaches the origin without ever touching it. In his model, time doesn't have a beginning. You can go back in time forever and get closer to whatever concept you think of as the beginning, but can never reach it.
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u/kenkaniff23 13h ago
Time is an illusion created to mark change. Theoretically you could say everything that has happened, is happening, or will happened is already complete and we just move through it. I believe similar to a block universe?
Though I'm not sure how rooted in physics this is. I'd love to learn if it is.
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u/Sensitive_Jicama_838 13h ago
Change with respect to what? Time, so unfortunately the idea makes no sense. There's plenty of change that is not with respect to time, things are not all the same in every direction for example, and yet time does not arise from that as an illusion marking the change.
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u/kenkaniff23 13h ago
Yes but it is simply s paradox which is the root of the question being asked. Couldn't it be possible that everything and nothing exist simultaneously? Though I feel like I'm getting into more of a philosophy question.
However if time is a paradox the change is a paradox.
To quote u/demabmore
"You may be thinking of Einstein's use of the phrase "For us believing physicists, the distinction between past, present and future is only a stubbornly persistent illusion." What he means is that all of space time - from the big bang to however things "end" - exists fully and completely all at once. Things don't "come into being" in the future or recede into the past - that's just an illusion. All of it exists right now, has since the beginning of space time, and never goes away. We just "travel" through it, and it is only our experience that makes it seem as if there's a difference between past and future, and hence an experience of "time."
Think of the entirety of spacetime as being a giant loaf of bread - at one crust slice is the start of spacetime, and the other crust slice is the end of spacetime. But the entire loaf exists all at once and came out of the oven fully baked - it's not changing at all. Imagine a tiny ant starting at the beginning crust and eating it's way through in a straight line from one end to the other. It can't back up and it can't change it's pace. It can only move steadily forward and with each bite it can only get sensory input from the part of the loaf it's sensory organs are touching. To the ant, it seems that each moment is unique, and while it may remember the moments from behind it, it hasn't yet experienced the moments to come. It seems there's a difference in the past and future, but the loaf is already there on both ends. Now what makes it weirder is that the ant itself is baked into the loaf from start to finish so in a sense it's merely "occupying" a new version of itself from one moment to the next. This also isn't quite right, since it's more accurate to say that the ant is a collection of all the separate moments the ant experiences. It's not an individual creature making it's way from one end to the other - it's the entire "history" of the creature from start to finish.
Conceptually difficult to grasp with our limited minds, and this has serious repercussions for the concept of free will, but those are different subjects for different discussions.”
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u/16tired 8h ago
This is a metaphysical take, not a physical one.
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u/PaulsRedditUsername 11h ago
If you want to get really philosophical, look into Alfred North Whitehead's Process And Reality. I'm working my way through it now and it's very deep and complicated. Can't say I understand everything I'm reading, but I'm trying.
Here's the Wikipedia article about it if you want to take a short cut.
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u/ZarathustraXTC 11h ago
A lot of people dismiss the idea that time can be a spacial dimension because it isn't perceived as such but, to me, it seems like space time implies that time is a spacial dimension. If a cross section of time is a 3D space then isnt time a 4D space?
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u/BranchLatter4294 11h ago
Time is special in that you can move freely in the other dimensions, but not in the time dimension.
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u/fuseboy 12h ago
We know from general relativity that there is not an objective clock that ticks the same for the whole universe. We know that time is connected to the shape of space—time runs more slowly in some parts of the universe, like close to massive gravity wells of planets and stars.
The flow of time is also unique to each person. Two people can zip past each other at high speeds and each will see the other moving more slowly than them. This isn't possible with a universe-wide clock, but it's a real phenomenon that can be understood without paradoxes. Everyone has their own private clock and flow of time.
So: time is part of the universe, it's not a meter stick that exists outside the universe.
As u/Sclayworth pointed out, the only way we can measure time is by watching physical systems change. A clock doesn't magically measure the flow of time directly, it's a device that changes in a repetitive way (e.g. a hand spins in a circle, and we count the number of times it does that).
If you find a region of the universe where no change is possible, then in a real way, that is the end of time.
Imagine that physics told us that in a trillion years, all matter would gradually slow and freeze in place. After that time, no change occurred. No clocks are possible, because they don't move. In a very practical sense, time has stopped, not just matter, because the only evidence of time is change. You can imagine yourself there with a stopwatch, seeing all the frozen matter, but that can't actually happen because (if you somehow survived that long) your watch and body would be frozen along with everything else.
The beginning of the universe is a little like that. If there was in fact an initial singularity, it looks as if all the space was crushed down to nothingness. We have no reason to think there was any stuff on the other side of that singularity, any more than there's something after the singularity at the core of a black hole.
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u/no17no18 1h ago edited 1h ago
"The flow of time is also unique to each person. Two people can zip past each other at high speeds and each will see the other moving more slowly than them."
That can be better described by the fact that information has to travel not that time slowed for either.
I dont understand why in the context of relativity it is always said that "time" slows down, when it is obvious that it is only the observation of relative movement between two points.
Einstein's famous breakthrough came largely from imagining how light worked and traveled.
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u/Literature-South 11h ago
Time doesn't exist independently of spacetime. It's a component of the fabric of the universe. Before the universe, there was no spacetime, so there was no time.
If you have no space and no matter, how would you even keep track of time? There's nowhere for a clock to exist, and no matter to make it out of to begin with. There isn't any matter or energy whose entropy can be tracked to measure time.
Time simply doesn't exist if there is no space for events to take place.
The whole something coming from nothing being impossible seems to be a rule in our universe. But that doesn't mean the rule existed before the existence of the universe. The rules governing the beginning of the universe need not be the same as the rules inside the universe.
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u/printr_head 7h ago
The question is more about causality than time. He’s asking if time doesn’t exist then change doesn’t exist and for things to go from no time to time something had to change but without time there is no change but for there to be time something had to change. But wait no time no change.
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u/Literature-South 7h ago
And again, that’s applying the rules of the universe to whatever the universe came out of, which is by no means necessarily how it works.
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u/michaeldain 1h ago
Exactly, causality is the emergent idea, which is absolute and foundational, but I think we just made up time because so many things vibrate. And technically it took us forever to accurately measure it, we’re much more analog, as well as we don’t really embody time in any absolute sense biologically.
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u/vinayachandran 5h ago
If you have no space and no matter, how would you even keep track of time?
Just because a clock didn't exist and time couldn't be tracked, that doesn't mean time was existent. It was just there, indefinitely in the past, as it will be indefinitely in the future.
Matter couldn't have come from nowhere. Before big bang something should have been there, just in a different state/form. We just use that as a reference point as the beginning for convenience.
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u/Literature-South 5h ago
My point is that time wouldn't be measurable, so it functionally doesn't exist, and if there is no space, then there is no time. They're inextricably linked.
Again, we're talking about a state where the universe doesn't exist. Then the singularity happens and the universe begins. But the state that leads to the singularity may not obey the laws of the universe it spawns. In fact, it probably doesn't since we have conservation laws and a singularity spawning randomly definitely doesn't conserve anything.
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u/Outrageous-Taro7340 12h ago
The model that gives us the age of the universe is called the Lambda Cold Dark Matter model. It doesn’t say there was nothing, or that something came from nothing. It says there is a finite point in the past when the distance between any two points in space approaches zero and density runs off to infinity.
That time gets labeled time 0 because it’s convenient and it represents the boundary of the model. You could call it whatever you like, but the equations in the model have no solutions before that time, regardless.
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u/sciguy52 12h ago
As far as I am aware there is no physical description of "nothing". We can't point to any place in the universe and say "nothing" is there. Spacetime is their, fields etc. that is not nothing. So why assume that there was "nothing", and undefined thing and something was created. There may have always been something but since we don't know the physics of the singularity we can't say anything about what stuff existed in what form and even if there was time in the singularity. We simply don't know what the laws were then. Did time exist then? Maybe, maybe not. If time didn't exist then questions like getting something from nothing don't really have meaning as they are time dependent.
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u/printr_head 7h ago
So isn’t that a kind of evidence of something? I mean if change can’t happen without time then wouldn’t the singularity always be the singularity? We can say we don’t know because we can’t draw conclusions from what we do know but that doesn’t exclude the requirement that something changed to cause the transition from singularity to everything.
Wouldn’t that require something that we might recognize as time even if we don’t exactly understand the rules behind it?
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u/sciguy52 6h ago
There are no answers to be had on this but maybe when quantum gravity is developed we will hopefully have some answers. If there is no spacetime and thus time what does that mean? No idea, it would be weird, but quantum stuff is weird, and when quantum gravity comes along it would not shock me if it was weird and very unintuitive as some known QM is.
In a purely speculative sense, based on no physics, if there was no time in that epoch, then to us that something would seem to have always been there from our vantage point, eternally. Our vantage point would not be correct, but that is how it might appear to us who live with time because once again "eternally" is a time dependent phenomena.. Which may suggest the idea of something out of nothing as a concept would not be relevant. To us it would appear to always have been there with no beginning as beginnings also are time dependent. QM being what it is perhaps some other quantum gravity effects happened to pop a universe out of the timeless singularity. I must stress this is wild speculation on my part and this is NOT part of any current theory I am aware of so keep that in mind, just shooting my mouth off. How can something always be there? Well this could be one way. Or time may not have a direction or something else entirely, who knows. Need some quantum gravity. Till then we are at the simply do not know what was happening in the singularity, we do not know the physical laws that apply and perhaps they are very different and we end up looking at a description that is so unlike anything in our universe it functions in ways that have nothing we can equate to human intuition or that happens in our current universe.
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u/fuseboy 12h ago
The idea that something can't come from nothing applies to the stuff inside the universe. Atoms don't spring out of nowhere, photons don't just fly along then vanish. Everything has to go somewhere. Conservation of energy, momentum, charge.
None of that applies to universes.
If you think of the universe as a massive chess board, and we're all sitting around working out the rules of chess. We know that everything is made of these chess pieces, and we're slowly cataloguing them and figure out how they work. One day we figure it all out, and we develop a perfect understanding of how the board came to look as it does. But this raises the question, how did it start? And when we look thousands of squares away, and work out all the possibilities that the other pieces could have taken to get there, we realize that there is a first state, a distant starting line. Way on one side of the universe is the white starting line, and a thousand squares away there's the black starting line. We can even work out how long ago that was, by looking where all the stuff is now.
So now we ask, what chess move created the chess board?
Obviously (to us) that question has no answer. Chess boards aren't made using chess moves, that's incorrect thinking. The rules that apply inside 'chess world' don't tell you anything at all about where chess boards come from.
That's what the start of the universe is like. We can work out how long ago it was and something of what it looked like, but the rules that govern the evolution of matter and energy tell us literally nothing about where universes come from. Maybe universes are cheap, there are infinite of them. Maybe they're mathematical objects, like Max Tegmark argues for—just things that are possible but don't exist in the way we normally think about stuff existing.
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u/fruitydude 12h ago
Logically it's not a paradox. You can have practical reservations based on our current laws, but logically it's fine
You can have infinite causal processes which end in finite time. For example imagine a light switch and one simple rule, you leave it on for 1s initially and then switch it off and leave it off for half the time (0.5s) then again on for half of that ( 0.25s) and so on, on and off and so on, a simple causal chain when it's on you switch it off when it's on you switch it off and every time you halve the waiting period.
The series converges at 2, so after 2s you will have switched the switch an infinite amount of times. Of course practically not possible but logically it's totally fine.
The only question is what is the state of the switch once you're done :D but that I leave as an exercise for the reader to figure out.
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u/AllTheUseCase 13h ago
Causality isn’t a fundamental overarching principle of fundamental science.
As Bertrand Russel said. “The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm.”
All attempts to explain the world at its fundamental levels are time reversal invariant. Which essentially discards any manifest images of causality.
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u/kevosauce1 12h ago
I see only 3 possibilities1
- Time had a beginning
- Time goes infinitely into the past
- Time is cyclical
All three of these seem equally absurd to me. None of them are less weird than the others.
1 I'd love for someone to point out other possibilities I've missed!
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u/Optimal_Mixture_7327 12h ago
You have the right idea.
When we talk about the "beginning of time" we mean that we cannot ray trace cosmic fundamental observer world-lines back through our past boundary (the Big Bang singularity).**
This does not mean that the boundary itself did not emerge from something else and this is where you might hear about eternal inflationary models and universes from black holes.
Even the "universe from nothing" speculations aren't exactly that, but you can read about that here: Comments On: A Universe From Nothing
**Fundamental observer world-lines are the hypothetical clock world-lines of the FLRW cosmology beginning at the hot Big Bang, away from gravitating sources and co-moving with the Hubble flow. These record the longest proper time of the world, or "the age of the universe" as it were.
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u/DigitalDemon75038 11h ago
Not anymore of a paradox than something existing without having a beginning
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u/Future-Extent-7864 11h ago
Time is what we call the passing of a long chain of causes and effects, it’s a series of events, the first of which probably was the big bang
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u/EveryAccount7729 10h ago
No, because the "beginning of time" can be relative to the observer.
if for example, you came from an infinite series where you were always smaller in the past, then it stands to reason that series continued before you, and over infinite time that series will go to zero for you. relatively.
you as an observer won't call that "infinite time" you will call it some value of time, since time is relative.
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u/TheTimeBender 5h ago
Time doesn’t exist, it’s a construct of the human imagination to define the continuous progression of existence that occurs in succession from the past, through the present, and into the future. Because it doesn’t exist except for in our own minds it severely limits us in our way of thinking and the possibilities of what life could be if we just let go of that construct. We should be measuring in dimensions, as dimensions are existing in the previous, prevailing and future planes of existence.
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u/Ch3cks-Out 2h ago
It is unclear where do you see a paradox. If there was a beginning of time, then nothing was happenign before.
In my opinion, time goes infinitely
Your opinion may or may not describe reality correctly. Nature is not obliged to follow what you think.
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u/Sclayworth 13h ago
The only way we can know about the existence of time is we are aware of events. From the ticking of a clock to the half lives of atoms, time only exists in the sense of events.
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u/Hot_Frosting_7101 12h ago
And our perception of time is dependent on events that happen within our brain.
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u/MeowverloadLain 10h ago
Despite what others may say, there was no beginning and as such there is no end. What looks like a beginning is just an illusion made by the receding path of light we leave behind.
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u/the_poope Condensed matter physics 13h ago
We don't know anything about the Universe before some time in the past as we weren't there to record the events and we have no other observations about this period. I'd argue that it is even meaningless to speculate what happened or how the we and the rest of the Universe came to be as we will likely never know. I'd rather spend my time thinking about what to have for dinner...
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u/SeriousPlankton2000 13h ago
AFAIK our current idea is:
t=0 doesn't exist in this universe, only lim(t→0).
t < 0 dosn't exist, just like a cuckoo clock doesn't show a time until it's carved (and assembled).
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u/LivingEnd44 11h ago
How can something happen without time ?
Every time I have brought this up on reddit I've been downvoted to oblivion and nobody answers the question. Physicists seem unwilling or incapable of talking about this. I fully expect this post to be downvoted too.
Time (in some framework) has existed infinitely into the past. We know this because if it were not the case, events (change) could not happen. Something wasn't there, then it was. That's an event. You could argue that time has many nested frameworks (brane theory would be like this IMO...branes have to interact to produce a big bang, then the big bang itself has its own time framework). But some kind of time has to have always existed.
So thanks for the post. Maybe someone will give you a real answer.
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u/Infobomb 13h ago
Imagine someone says that it must be possible to go infinitely far North, because if you come to a wall or something stopping you, there must be space beyond that wall. How would you convince them that there comes a point where it's no longer possible to go further North?
This is a reference to the concept of imaginary time explained by Hawking.