According to modern physics, does the past exist?

How does modern physics conceive of time? I've heard it compared to a 4th dimension, like space... but that implies that all of time exists. What makes the present moment the present moment? Does the past exist in a different way than the present or the future?

I'm eating kraft singles Phone Post 3.0

danggook - I'm eating kraft singles Phone Post 3.0
You were two minutes ago. In the past Phone Post 3.0

I'm about to flush the toilet Phone Post 3.0

KneeUpperCut Ios - I think in order to understand modern notions of time, one must first understand the history of time in order to help contrast the two. If you look back at ancient greeks there were scholars who felt that time was discreet and those who felt time flowed like a lake. A famous example involved two gentleman (Tucreppueenksies and Sekoj) both from the high court of officianoes, a public office which housed the top 10 finest scientists of the day. They argued day and night about the nature of time until finally they came up with a genius way in which to determine who was right.

In order to determine whether time was discreet of flowed like a lake, they would take a bucket of cold water tie it to a string and rotate it until the string became taught. They would then pour out the water, and replace it with distillied liquour and goats milk. While this step seemed superfluous Sekoj, who happened to be from the house of Stark, a wealthy family who at the time had claim to the kingdom, reasoned that the goats milk contained enough fat to offset the intertial drag given off by vorticies created by the angluar momentum upon releasing the bucket into freefall.

I won't bore you with the details, however the experiment concluded and it turns out Tucreppueenksies was right all along. Time is in fact discreet.

Tucreppueenksies was ass backwards about time, IMO.

Voltaire was THE seminal force of enlightenment in the 17th century and you can all go suck his big old donkey dick!

This ^^^^^^ didn't happen.


PrisonMattressPuncher - There is not 'past'. Time is a man-made construct. There is only change. Time is simply a measure of change.

This was Aristotle's view, if memory serves. Can you explain how you understand it, because it is fairly cryptic? And how does this view of time relate to modern physics (which speculates on the possibility of things like time travel, for instance).

Sub Phone Post 3.0

Tiresias - What are the "criteria of existence for the past?" If the criteria are clear, then the question can be answered without any dispute. If the criteria aren't clear, then we don't even know what we're asking. Questions about existence normally presuppose, unquestioned, the framework of time. So what framework is a question that violates this (ie calls usual framework, which includes time, into question) asked in? And how could we possibly establish criteria without knowing this? It seems like we're in danger of talking a lot about a question that doesn't even begin to make sense... Phone Post 3.0

I am asking primarily about how modern science conceives of time, and so the criteria of existence would be whatever criteria is implicit in modern science, which I agree would need to be clarified. Quite simply, I've heard people say that time "is" the fourth dimension. This implies some understanding of what time is, and (perhaps more importantly) what time is not. And so some understanding of the existence of time (and some criteria for existence). I was wondering, based on this understanding of the existence of time, what is the past as opposed to the present? How does the past exist, according to modern science?

I like the theory that we actually living in the past of whoever create the universe!!! Phone Post 3.0

I always liked the thought that the past or future don't truly exist. The present is the only reality we experience. Which makes it even more tragic that most people spend their 'present' thinking about their 'past' or worrying about their 'future'.

Jambo888 - 
Sennin - 
danggook - I'm eating kraft singles Phone Post 3.0
You were two minutes ago. In the past Phone Post 3.0

unless there isn't a past. then he's always eating kraft singles. and never eating kraft singles. at the same time.

if someone was far enough away, with a powerful enough telescope  they would be seeing him eat the kraft singles right now.

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KneeUpperCut Ios - 
gord96 - I always liked the thought that the past or future don't truly exist. The present is the only reality we experience. Which makes it even more tragic that most people spend their 'present' thinking about their 'past' or worrying about their 'future'.

Well if you don't plan for your future, your present will be spent living in a cardboard box begging for money.

i didn't say anything about not planning. planning is important and a good use of the present. worrying is the word i used.

Tiresias - But we still have to know what the difference between "existence" and "non-existence" is for the past, before we even think about the science. How do those predicates apply to time? The form of our language makes it seem they could, but there is NOTHING in our practical experience to guide us here... Phone Post 3.0

I'm not sure where we are missing each other. Modern science (speaking broadly) makes claims about the nature of things, about what they are and are not. For instance, one such claim might be that time is the fourth dimension. This implies some understand of what time is and what it is not, the nature of time. I am trying to clarify what time (and, in particular, the past is) according to this understanding.

Now, this scientific understanding may be wrong, or it may be hopelessly mired in metaphysical confusions, which should be jettisoned. This is actually what I hope to find out by having people who are well versed in modern science answer the question.

Tiresias - Why not drop the confusing metaphysical language of what time "is", and simply stick to discussing what can be clearly observed, measured, or theorized in relation to our concept of time? The metaphysical language is just a kind of shorthand for this normally anyway. Phone Post 3.0

Because modern scientific theories use this confusing metaphysical language of what time "is". And that is what I am asking about.

I have the pictures of myself from the past and more to show age-progression to evidence the passing of moments to string them together and call that "time."

time is a concept like "location"


just because you can't currently observe the past doesn't mean it's non-existant.

just as not being able to currently observe a location on the other side of the planet doesn't mean it's non-existant.