# If there is no energy, does time exist?

Discussion in 'Physics & Math' started by wegs, Jul 6, 2019.

1. ### SeattleValued Senior Member

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Why are we capitalizing AGE? Were you thinking that maybe time was the same as height, width or depth? Why not define what you call AGE as TIME?

3. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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Why are we capitalizing AGE?

To distinguish it as the subject

Were you thinking that maybe time was the same as height, width or depth?

Those are PROPERTIES assigned to some stuff but as TIME does not exist no properties can be assigned

Why not define what you call AGE as TIME?

Because they are NOT the same

AGE is a arbitrary measurement between a arbitrary NOW moment and another arbitrary NOW moment

So have you a PROPERTY of TIME for me

5. ### SeattleValued Senior Member

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I'm good with thinking of time and age as being comprised of the same thing.

What about time doesn't work for you other than that you don't have a property for time? Where is time letting you down?

7. ### TheFroggerValued Senior Member

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Michael345. If you watch the television programme, "The Chase" the presenter may state at the end of a player's game that they could have gone for the higher offer, because at the end of the player's turn, the chaser was two steps behind. However, the chaser may have only been one step away from the runner previously in the game. It is only with the passage of time that we can know which is true.

This is time.

8. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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Where is time letting you down?

Like god, no evidence, no properties

You appear to have a blind spot with regard to PROPERTIES and your inability to name any property assigned to time is noted

I personally cannot think of anything which exist and which I believe in that I cannot link it with at least one property

• check difference between TIME and AGE, although feel free to be incorrect
• find a property of TIME you can slay me with

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Repeat ?

10. ### TheFroggerValued Senior Member

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What about learning to walk, Michael345? Is that a measurement of time...?

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No

12. ### TheFroggerValued Senior Member

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But the creature has taken the TIME to ob-serve, and learn it.

Like Bambi...

13. ### SeattleValued Senior Member

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I have no interest in "slaying" you. You don't think you are the first person to question whether time is real or not do you?

By not "believing" in Time, how does this affect your world view? Before replaying, please think of a way that this has a real effect on you.

14. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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No - so

Not going to bother giving replies to you when no reciprocal replies coming back

15. ### TheFroggerValued Senior Member

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Well f*ck me, Michael345. What 'av you bin readin'?

16. ### exchemistValued Senior Member

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Well yes, if you hypothesise something that can never be detected it is a bit hard to see how it can survive Ockham's Razor.

Whereas we have abundant evidence that seems to show there was a past, before there were any human observers, in which change took place. That, in my view, justifies us in applying our concept of time to the pre-human past, just as we apply our concept of spatial dimensions, or any of the other parts of our framework for making sense of the world.

You can play various cogito ergo sum -type reductionist philosophical games, about what can be proved to be real, if you like, but it gets you nowhere in practice, it seems to me.

Science is not about what can be proved, it is about models to account for experience of nature. Those models depend on there being a past in which values of time and space can be assigned to systems.

Last edited: Jul 20, 2019
17. ### James RJust this guy, you know?Staff Member

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wegs:

It's sounds like you're looking for a cause for time - a reason that time exists.

What I would say, in the first instance, is that science doesn't really look for ultimate causes, most of the time. Science's job is to describe or model the world as we find it. We observe that stuff doesn't all happen at once, so we build this concept called "time" into the models.

Energy is another kind of model. It is particularly useful because it is often a conserved quantity, and physicists find such quantities to be very useful for solving problems and modelling systems.

In fact, things go deeper than that in physics. There's a really powerful theorem due to Emily Noether which says that for every symmetry in nature, there is an associated conserved quantity. For example, it is an observation that the laws of physics do not vary depending on our spatial location. If we carry out the same experiment in two different locations, under the same conditions, then the results will be the same. From this, it can be shown that momentum is a conserved quantity, which is rather interesting and unexpected.

So what about time? Well, another observation is that the laws of physics don't seem to care much about whether we do the same experiment yesterday, or today, or tomorrow. The results are the same, regardless. So, there's some symmetry in time, and there should therefore be a conserved quantity that goes along with it. It turns out that the relevant conserved quantity that comes from time symmetry is energy. So, time and energy are related in quite a deep way.

At the risk of harping on a theme I've raised before, it is important to realise that energy isn't a substance. Mostly, designating the "zero" point of energy is completely arbitrary, so when you say a system has no energy (i.e. its energy is zero) that doesn't really imply anything very special under a lot of circumstances. In particular, the fact that some system or other has zero energy shouldn't have any special effect on time - at least not in terms of causing time not to exist or something.

I don't like that statement much. We are only confident in the accuracy of our best big bang models back to a short time after the start of the universe (specifically, from about $10^{-43}$ seconds after the start). To push things back further to look for first causes, we need better models.

Using current models, though, we run into problems if we try to talk about times "before the big bang". It's a similar problem to trying to talk about points on the Earth's surface that are north of the north pole. We hit a conceptual or logical wall - a singularity, if you like.

Arguably, there's zero net energy right now, when you consider the entire universe. Maybe that has always been the case. As for "before the big bang", we tend to hit that wall I just mentioned. Some people would argue that it is actually meaningless to talk about time or energy before the big bang.

We don't know. We don't know whether the big bang had a cause, or what that cause was if it had one. There are hypotheses out there, but still a long way to go before we get definite answers.

Modelling and trying to explain things doesn't change them. It can change us - our understanding of our world and our place in it.

wegs and exchemist like this.

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Don't get me wrong, you are of course correct in saying that we know nothing of what was, or what happened before t+10-43 seconds. But as cosmologists now assume [sensibly imo] that point singularities of infinite densities and spacetime curvatures do not exist, then I see it as more logical saying that space and time [as we know them] evolved from a hot dense state to what we are familiar with.

20. ### exchemistValued Senior Member

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James, a slightly tangential question: I don't know much about Noether's theorem, but that the invariance of the laws of physics with position in space leads to conservation of momentum, while the invariance in time leads to conservation of energy calls to mind two common expressions of the Uncertainty Principle, arising from the non-commuting of their respective QM operators. This does not feel like coincidence. Do you know of a reason why QM pairs these quantities in the same way that Noether's theorem does?

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My definition of time is simply the measurement of intervals between sequential events. Time as we know it, started at t+10-43 seconds along with space, and contrary to what others have said, the observed changes and movements that do occur, occur "IN" time, not specifically because of time.
But then again, as I said, defining it is difficult.

22. ### SeattleValued Senior Member

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Of course not. I'll take my ball and go home too.

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Mick, are you out of bed yet? The first thing with regards to time, is that the best brains in the world recognise that defining it is controversial. You ask for properties....Time has direction, and always moves/flows towards the future.... Time has order, and obviously we always see one event follow another that follows another.
A thing/entity/model need not be physical to be real. Think about a magnetic field. We see effects [as we see effects of time] that we define as a magnetic field.
But as I have said, it is a debatable and controversial topic.
You, it seems have read a book [I forget which one] that sees time as you put it and you seem to like that description. I have given links by Sean Carroll that see it differently and seem to suggest that the question that needs to be asked is "is time fundamental"
In the most simplistic terms, space is what stops everything from being in the one spot...In that sense space is real. Time stops everything from happening at the one instant...equally in a sense that makes time real. space has three dimensions...time is a fourth dimension that we need to specifiy a happening.
Together as spacetime, it is the multi-dimensional framework within which we locate events and describe the relationships between them. It is real within the realm of GR, and can be warped, curved, twisted, and which we feel as gravity....Hence similarly the analogy of a magnetic field, in that we see the effects of the field and that's all.
here is another link/article that I hope conveys what I'm trying to say.......
https://www.livescience.com/29081-time-real-illusion-smolin.html