What is "the present" and how long is it?

[Not_By_Chance]

I had a thought recently while considering what to make of time. Now whether one believes the Christian explanantion that God created time (and space and matter) but exists outside of it or whether you allude to Einstein's idea of time being inextricably linked to space and matter but don't believe in a Divine origin, there seems to be no doubt that it exists, at least for the time being! But given all that, what exactly is the present and how long is it? Is it a second, a millisecond, a microsecond or is it just an illusion; an interface between past and future if you like (which is sort of what I am beginning to think)? So for example, the words I have just written are already in the past, but those I haven't are still to come and therefore in the future. It seems like time is another one of life's great mysteries, of which there are many.

 

[distressedson]

imo Time and space actually do not move. You do not change them. Your spirit passes through spacetime on the path of your human body, and that is what you experience. Your spirit is a whole, it doesn't have multiple moving parts and particles like a computer (or the human brain) and experiences of spirit cannot be measured by little quarks and volts like matter or energy.

Just my philosophy. I've actually thought about this a lot and this is the only conclusion that makes sense. There is no such thing as a 'present' that can be measured (or if it could be measured it would be infinitesimally small) and you are constantly moving forward toward your decoupling of spirit from mind and body

 

[Rubiks]

unless time is discrete (I have no idea if it is) then the present is infinitely small, similar to a point on a graph. Interestingly, the present is never actually experienced by an individual, since it takes time for the neurons in your body to send signals to your brain. It then has to process it.

 

[tansy]

But does time really exist as an entity? I mean, if there were no movement of the sun, planets etc etc...if for example it was always light, then perhaps we wouldn't notice the passage of 'time'. Doesn't it say in the Bible that God created the sun etc etc in order for us to mark the seasons?
I sometimes think that perhaps the Creation including us is in a kind of bubble which God surrounds (and also is within being omnipresent) and that's why He knows the beginning from the end. But who knows...beyond my tiny mind to grasp.

 

[J_B_]

I had a thought recently while considering what to make of time. Now whether one believes the Christian explanantion that God created time (and space and matter) but exists outside of it or whether you allude to Einstein's idea of time being inextricably linked to space and matter but don't believe in a Divine origin, there seems to be no doubt that it exists, at least for the time being! But given all that, what exactly is the present and how long is it? Is it a second, a millisecond, a microsecond or is it just an illusion; an interface between past and future if you like (which is sort of what I am beginning to think)? So for example, the words I have just written are already in the past, but those I haven't are still to come and therefore in the future. It seems like time is another one of life's great mysteries, of which there are many.

I guess I'll be the wet blanket. "Present" is not a scientific term and has no relation to scientific constructions like "spacetime". Rather, what constitutes the "present" depends on the context of the speaker. It could mean anything from "this exact nanosecond" to "this historical age". Much of language is that way. In fact, one theory of language is that we learn to communicate contextually and not per dictionary definitions of words.

Next, not all Christians subscribe to saying God created time and is outside time - as if it's some physical thing. I am one who doesn't. Rather, time is simply a way of marking motion.

Finally, many scientists shy away from musings on whether time exists, whether it's a thing, etc. There are strong instrumentalist undercurrents, which means more of a "if it works, go with it and don't worry about the philosophy" approach.

 

[Chesterton]

Finally, many scientists shy away from musings on whether time exists, whether it's a thing, etc. There are strong instrumentalist undercurrents, which means more of a "if it works, go with it and don't worry about the philosophy" approach.

But isn't it important to Einstein's theories that time be a real thing?

 

[J_B_]

But isn't it important to Einstein's theories that time be a real thing?

Since I don't have a physics degree, I can't answer that with any authority. But, in my opinion, no, I don't think it's important. Further, my impression from physicists is that it's not important.

 

[tansy]

I guess I'll be the wet blanket. "Present" is not a scientific term and has no relation to scientific constructions like "spacetime". Rather, what constitutes the "present" depends on the context of the speaker. It could mean anything from "this exact nanosecond" to "this historical age". Much of language is that way. In fact, one theory of language is that we learn to communicate contextually and not per dictionary definitions of words.

Next, not all Christians subscribe to saying God created time and is outside time - as if it's some physical thing. I am one who doesn't. Rather, time is simply a way of marking motion.

Finally, many scientists shy away from musings on whether time exists, whether it's a thing, etc. There are strong instrumentalist undercurrents, which means more of a "if it works, go with it and don't worry about the philosophy" approach.

Not that I'm a scientist nor a theologian, but I don't really think time exists either. Like you suggest, I think we just use the concept as a way of marking the passage of 'time' so we know where we are. As it says in Scripture, God created the 'heavenly bodies' for us to mark the seasons. I don't think we'd even be aware if it were, say continually light and if there were no autumn, spring, monsoon season etc. etc. It's like when we say 'Today went really fast' or 'really slowly'. If we had no way of measuring, we wouldn't even ralise...I don't think.

 

[Radagast]

But isn't it important to Einstein's theories that time be a real thing?

Of course it is.

The difficulty with Einstein's theories is that an event may be in the past for one observer, in the exact present for a second, and in the future for a third, depending on how fast, and in what direction, the observers are moving.

Einstein's theories thus imply that space-time is a four-dimensional block, in which the future already exists.

 

[Jok]

Since I don't have a physics degree, I can't answer that with any authority. But, in my opinion, no, I don't think it's important. Further, my impression from physicists is that it's not important.

You don’t need a physics degree to know that it’s a fact that time is relative

 

[J_B_]

You don’t need a physics degree to know that it’s a fact that time is relative

OK. I wasn't challenging that, so ... OK.

 

[J_B_]

Of course it is.

The difficulty with Einstein's theories is that an event may be in the past for one observer, in the exact present for a second, and in the future for a third, depending on how fast, and in what direction, the observers are moving.

Einstein's theories thus imply that space-time is a four-dimensional block, in which the future already exists.

I believe you're referring to simultaneity, and I don't think that's how it works. It doesn't refer to one event, but rather to (at least) two events. Whether the two events appear to happen simultaneously depends on the observer's frame of reference. As such, the principle seems to state that relativity doesn't have a notion of past, present, and future rather than declaring what they are.

But, again, those with physics degrees can correct me if I'm wrong.

 

[Jok]

OK. I wasn't challenging that, so ... OK.

Lol sorry I wasn’t trying to be cocky, maybe I sounded cocky by not saying more, I meant that even GPS satellites are proof of time relativity, they have to be slightly adjusted for time differences

 

[Radagast]

I believe you're referring to simultaneity

Yes.

and I don't think that's how it works

You are incorrect.

Each observer has a hyperplane through spacetime that establishes their "now." The hyperplane includes all events simultaneous with their local "now."

From the point of view of the observer, this hyperplane splits space-time into "past" and "future."

But all these hyperplanes depend on the observer's motion. Speaking globally, "past," "present," and "future" are meaningless. There is only a big block of spacetime.

From Wikipedia:

Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

 

[J_B_]

Yes.



You are incorrect.

Each observer has a hyperplane through spacetime that establishes their "now." The hyperplane includes all events simultaneous with their local "now."

From the point of view of the observer, this hyperplane splits space-time into "past" and "future."

But all these hyperplanes depend on the observer's motion. Speaking globally, "past," "present," and "future" are meaningless. There is only a big block of spacetime.

From Wikipedia:

Event B is simultaneous with A in the green reference frame, but it occurred before in the blue frame, and will occur later in the red frame.

Fair enough. I meant past, present, and future in the global sense, but I didn't say that so it would be petty of me to harp on the point. You win that part.

But let's ponder your other phrase for a moment:

Einstein's theories thus imply that space-time is a four-dimensional block, in which the future already exists.

I assume there is an observer attached to the red, green, and blue frames who at some specific instant are coincident at A. Now let's suppose Blue wants to impress Red (he has a crush on her) and decides to do a trick where he predicts the future to her. Would it be possible for him to do that, and how would it work?

In other words, in order to communicate with her, they will have to remain coincident at A, or they will have to become coincident again at some other instant so they can communicate, or he will have to be able to send a message to her through spacetime ... something like that. How would it work, and how could be convince her he knows the future (or, at least, her future)?

 

[grasping the after wind]

There is only the present. What is, is and what is not, is not. The words on this thread are all in the present they are not in the past or the future because the past and the future do not in reality exist.

 

[Radagast]

I assume there is an observer attached to the red, green, and blue frames who at some specific instant are coincident at A. Now let's suppose Blue wants to impress Red (he has a crush on her) and decides to do a trick where he predicts the future to her. Would it be possible for him to do that, and how would it work?

No, for other reasons that won't work.

 

[J_B_]

No, for other reasons that won't work.

Right, which is why I think the statement quoted in post #15 doesn't hold up. When Blue perceived the event, he was not in his future or past. He was in his present. And if he is not able to communicate that to a reference frame where the event is in the future (i.e. Red), then Red will never be aware this future, so called, exists. When the event is perceived by Red, she will perceive it in her present, not her future. No one ever perceives an event in their past or future. They may know it occurred in their past, but they don't perceive the past. And the future remains unknowable and unpredictable - a complex web of possibilities - such that, if it does exist, it's useless to know it exists.

 

[Radagast]

Right, which is why I think the statement quoted in post #15 doesn't hold up. When Blue perceived the event, he was not in his future or past. He was in his present.

Well, the missing factor is that you don't become aware of distant past events immediately; it takes time for light to reach you.

I found the rest of your post difficult to understand, I'm afraid.

 

[J_B_]

Well, the missing factor is that you don't become aware of distant past events immediately; it takes time for light to reach you.

I found the rest of your post difficult to understand, I'm afraid.

Were I to try to simplify what I said, it would go like this: Just because some local event may exist a few seconds in the future (a few minutes, whatever), it does not follow that the totality of the future exists in the sense of most theological discussions - that time exists or is just a concept - that all of eternity is or is not determined - that God is in time or he isn't.

It doesn't answer any of those questions. At best it's just a matter of some practical adjustments to satellite orbits and the like.