An Interesting Thought About Time

**StephL** · 04-28-2015 03:25 PM

I hope others enjoy this stuff as much as I do and I also hope this post will clear up matters at least somewhat. It took me considerable time to be honest, I've been learning a lot on the way, but it wasn't an easy task to assemble a picture of the state of affairs.

You won't easily find it spelled out in popular science material, but here's Einstein's position on whether time and space exist or not, taken from https://einstein.stanford.edu/SPACETIME/spacetime2.html

Space and time exist absolutely, but are not independent. They are interwoven into a single fabric called spacetime.
Spacetime does act on matter, by guiding the way it moves. And matter does act back on spacetime, by producing the curvature that we feel as gravity.

That's the widely accepted view in the scientific community, the same view which is also presented in the video below, despite the somewhat misleading title.

It is a very common misconception that Einstein would have said time is only an illusion and would have meant it doesn't exist in reality.
What he did say was this:

"The distinction of past, present and future is only an illusion, however persistent."

For an explanation what exactly the above quote means - please - watch a little 4 min. segment of the following video, you won't regret it, it's a fantastic visualisation making it instantly understandable.
And it's so adorable with the little alien on a bicycle that you won't easily forget, and it's important!

Start from around 22:38 min:

Just reading the title can easily lead to misunderstanding. What they are on about does not contradict Einstein's position that time and space have an absolute (= fundamental, see below) existence in physical reality in the form of spacetime.
Instead it explains that and how our experience of time is an illusion, how time doesn't behave as it intuitively seems, but instead behaves very differently in certain circumstances, but behave it does.

Einstein's theory predicted that spacetime itself would bend in the vicinity of a massive object for example, and confirmation was gained by observing this effect during a total solar eclipse.
Light always travels the shortest way and in a straight line through space until it meets an object, but light from farther stars which passes closely by the sun undergoes a curvature and such its source appears to be somewhere else than when viewed in the night sky.
Like this:

In 2013 a new round of wondering about the nature of spacetime was kicked off by a mathematical "discovery", the amplituhedron.
Again you can find popular science sources under headers announcing the groundbreaking new insight of how "time and space are not real".

What is meant this time around is again not that spacetime isn't real, but that it might not be fundamental.
Meaning it might instead be a manifestation, an emergent property of an even more basic reality from the quantum realm.

Quantummagazine - A Jewel at the Heart of Quantum Physics:

Physicists have discovered a jewel-like geometric object that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality.

“This is completely new and very much simpler than anything that has been done before,” said Andrew Hodges, a mathematical physicist at Oxford University who has been following the work.

A picture of the Amplituhedron:

Somebody asked the following question under one more of those slightly confusing headers: Space and Time Are Illusions, Apparently:

In other news today, the discovery of the amplituhedron, "a newly discovered mathematical object resembling a multifaceted jewel in higher dimensions," means that space and time may be illusions. If you understand this, please explain it in the discussion section below.

Here's a beautiful answer she got from somebody calling themselves effdot:

Imagine this marble track in your mind's eye.

Imagine that you had a marble going down that track. If you wanted to know here the marble would be at any point in time, it's easy to see. You know the shape of the track, the possible paths the marble could take, and all the info you need.

Now, imagine that the same marble track was invisible. In fact, imagine that you had no idea what that marble track 'looked' like. The only way you know how a marble might travel along it would be to blindly drop it. If you got lucky, you may find the entrance to the track, and the marble itself may follow an orderly pattern. But without any idea of what the track 'looks' like, you have to make all kinds of probability calculations to guess the speed or position of the marble.

What these guys have done is create a mathematical model of the very complex marble track that particles travel along. Which means you can just do a volume calculation of that object relative to the particle to determine its paths.

Another snippet of the article from Quantummagazine:

Puzzling Thoughts

Locality and unitarity are the central pillars of quantum field theory, but as the following thought experiments show, both break down in certain situations involving gravity. This suggests physics should be formulated without either principle.

Locality says that particles interact at points in space-time. But suppose you want to inspect space-time very closely. Probing smaller and smaller distance scales requires ever higher energies, but at a certain scale, called the Planck length, the picture gets blurry: So much energy must be concentrated into such a small region that the energy collapses the region into a black hole, making it impossible to inspect. “There’s no way of measuring space and time separations once they are smaller than the Planck length,” said Arkani-Hamed. “So we imagine space-time is a continuous thing, but because it’s impossible to talk sharply about that thing, then that suggests it must not be fundamental — it must be emergent.”

Unitarity says the quantum mechanical probabilities of all possible outcomes of a particle interaction must sum to one. To prove it, one would have to observe the same interaction over and over and count the frequencies of the different outcomes. Doing this to perfect accuracy would require an infinite number of observations using an infinitely large measuring apparatus, but the latter would again cause gravitational collapse into a black hole. In finite regions of the universe, unitarity can therefore only be approximately known.

To go off topic a bit - illusion actually fits very nicely for time if you apply the proper definitions of terms.
An illusion is a misinterpretation of a perception of something actually existing, while a hallucination is a purely endogenously generated perception.

The usual effects of most psychedelics are mere illusions for example. Say there's a lamp and what you see is an elf with an umbrella doing a little jiggle-dance. But there is a lamp, not nothing. Otherwise it would be classified as hallucination.

Same with time, there is something which we mistake for what we commonly understand under the term time.
Einstein gave us a conceptualization of this something with his spacetime fabric and it got demonstrated again and again that space and time really behave like that. Without RT we wouldn't be able to use satellites for another example...

Now it looks as if QM can reduce spacetime further and explain it as an emergent property of something else yet again.
Like finding yet smaller particles in atoms, which were thought to be the smallest, most fundamental building blocks of matter, but are not.

**StephL** · 04-29-2015 12:00 AM

Happy you like it, Sageous!

**Sageous** · 04-29-2015 03:39 AM

^^ I did; interesting stuff indeed!

The thought that bubbled up after reading your post was that space-time seems to be physical reality's "qualifier;" or that which makes reality "real" for us.

In a sense, space-time doesn't need to be physically existent to have a real impact on reality. So, whether as tool or undiscoveed physical force, space-time for us must exist in order for us to exist in an intelligible manner.

Not sure if that makes sense, but it was where my slightly arguably addled mind went. That's probably not the response you were looking for; hopefully others will chime in now...

**StephL** · 04-29-2015 05:38 PM

I like the thought about spacetime as the qualifier of physical reality for us.
We as conscious here-and-nows moving about in it, and spacetime qualifies what is the case of the matter.
Or something...

I wasn't looking for a specific response, it's more I wanted to present my findings - and the little alien on it's bike*!

When coming across this thread quite a while ago, I did some looking and reading around and then posted something. But shortly later I noticed, I had gotten some things wrong and deleted it. Now I had some leisure and it took my fancy again and so I embarked on another fun voyage through the wonder of internet self-education. I love these things where physics becomes so fantastic and baffling that indeed it fits into the philosophy department!

Goes and tries to unknot her mind with a bit of meditative darts-throwing...

*Edit: it is really worth watching that little segment, even my husband, who's a mathematician said he wouldn't have seen it presented that well and how memorable it would be. I prefer BBC-style documentaries, but hey ho - they did that in a lovely way!
I think it's an adaptation of a graphic of our light-cone from the Hawkins book "Short Story of Time".

**Sageous** · 04-29-2015 06:17 PM

Originally Posted by StephL

When coming across this thread quite a while ago, I did some looking and reading around and then posted something. But shortly later I noticed, I had gotten some things wrong and deleted it.

I was wondering about that!

**StephL** · 05-02-2015 07:53 PM

Yeah, I had to find out that there's a difference between not real and not fundamentally real, and that took a while, but I was intrigued.
Since I spoke of internet self-education, I almost feel a bit bad about the overall quality of the above video, I didn't even watch it entirely...

So now I want to redeem myself. This is a real marvel, they both are brilliant speakers besides actual cutting edge physicists, Krauss (Cosmology I believe) and Greene String Hypothesis, as he himself points out. You will not be bored, it's a fine conversation and you and won't have to wait for finally something new and/or interesting!
Enjoy!

**MrPriority** · 05-03-2015 12:45 PM

Thank you for these very nice and insightful posts Steph

These kind of discussions are always on a rough territory, I think. On one hand it is wonderful to debate these questions that I think are very fundamental to being a human. To think about how the world works and come up with these new ways to explain things can certainly be thrilling. Even more so when another party can inspire you to whole new levels of thoughts about the question.

On the other hand, there is a lot of information already out there. As loads of people have been thinking about this stuff. And unfortunately we don't all have a basic concept on what the scientific world has revealed so far. (I partially blame school systems for this

) And I don't expect people to. Hell I don't think I know enough to really debate about this either.

So we are on a rough territory. On the one hand thinking and debating about this stuff is fun and definately a good thing to do. I firmly believe that one should always question reality. On the other hand we most likely won't come to any new idea's. And by the off chance we do, then we most likely won't go ahead and back it up with the mathematics needed for that. So even though it can feel very profound and ground breaking, chances are our thoughts are wrong. Though let me state again: I do believe that it is very healthy and good to have these kinds of debates. I just like to keep this in the back of my mind.

Now the real problem arises when 2 parties with a different level of understanding come to debate. Especially when one knows the other is wrong, but cannot seem to show the other that he in fact is. Which is totally understandable, explaining something is a skill. That's why teachers have to learn how to teach (and even then there are a lot who still can't really do it).

This is just one of the things that can lead to conflict instead of a healthy debate. We can't ask anyone to educate themselfelves on the matter before posting. And we can't ask educated people to learn how to properly convey their thoughts, so that people with a lesser understanding of the matter can understand them. We can only hope that people share their point of view. And that they try and understand what others are saying.

So to get to my point (finally

). I think it's great to see you (StephL) go to such lengths to make an educational post. Simply to give people a little bit of scientific understanding of the matter. I think that is a very good approach to the matter and it makes for a very healthy debate. If more people did it like that, we would all be a whole lot smarter after reading/participating in this thread, so thank you for that

**StephL** · 05-03-2015 04:09 PM

Thank you!
Very happy you like it, MrPriority!
But I need to flee from this thread now, not to keep editing, because I'm still unhappy with how I put zig things and might find yet more stuff...

And after finding the string theory thing, which does not actually pertain to the topic, but was so - yeah - educative and entertaining and fascinating, also nice and humorous and philosophical, that I wanted to share it - after finding that, I found something which does pertain.

It's about the existence of nothing (which is questionable).
Not really for nothing they've got two - let's for simplicity call them philosophers - on one side of the panel, too.

I said somewhere nothing cannot do that and that's also wrong, nothing can do a whole lot of stuff and there's different kinds of it as well!

Before throwing it in, I want to say a few things, this is the Isaac Asimov Memorial Debate, it's five people who know what they are talking about, and they do that, it's not a debate in the usual sense, it's a conversation hosted by Tyson, and you eavesdrop. Tyson tries to keep it on a followable track, and for the first time watching, he didn't really succeed for me, my eyes kept glazing over in confusion, but since I really, really liked it - I gave it a second watch, and maybe I'll do a third, because astoundingly, I did understand a lot more the second time around.

You gotta love Prof. Friedrich Gott, astrophysicist and cosmologist with his jacket from the future and multiverse-model in a piece of tupperware - and for one of his descriptions of nothing:

What is behind your head? What is beyond your field of vision?
It's not black, it simply isn't there for our perception, because we have no retinal cells pointing in that direction.
You go watch for more impressive variants of that, if you want to.

Edit: now - I had watched late last night, and now I just jumped in at points to show my husband, and I understood perfectly well, and didn't find something to demonstrate him where they lost me. So do not be deterred by what I wrote on glazing over.
Ah - I should stop worrying if people might watch or not, I will never know who might come across it and can only hope for the best!

Another after another etc. edit:
I keep finding things, this is nice, I was too lazy to go into thermodynamics and the arrow of time without finding the great documentary I once watched. I was looking for that in vain when I found the little alien. Aanyway:
New Quantum Theory Could Explain the Flow of Time | WIRED