does time exist?

OGIONIK wrote:

oh, i see !

yeah, i hope that explains what is meant by time dialation and how time can slow down. it's a pretty simple concept if you understand what a vector is and how they work.

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pswfps wrote:

In relativity, gravity is the name given to the curvature of space-time associated with matter, isn't it?

I'm wondering which is the cause and which is the effect. Does matter cause the curvature of space-time or does the curvature of space-time cause the matter?

I have wondered the same thing.

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The curvature of space-time does not exist in objective reality. Space-time is a human concept, one particular coordinate system that we enjoy doing our math with.

If you use a coordinate system based on theoretical tachyons, there is no curvature because gravity does not effect their movement. If you use a coordinate system based on temperature, then the "curvature" of space is mottled and irregular, based on the temperature of adjacent objects. You can choose any reference you want as a coordinate system, then build up the math around that.

The actual physical reality is neither bent nor straight. We simply observe objects moving in a certain path and agree to all use that as our "straight line" reference, so our math can be a bit simpler and more consistent with each other.

Group consensus does not create the reality.
A useful concept does not create the reality.
We still have to go look at the evidence all around us to see how time and space actually behave, creating our concepts and approximating language from that.

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Quote:

Group consensus does not create the reality.
A useful concept does not create the reality.

Incorrect unless you are a "naive realist".

If you are, you believe there is some "underlying reality" despite Heisenbergs comment "we never observe the world, only the results of our actions on the world".

If you are not, then "reality" equates to "goodness of fit" of the explanatory model which is subject to paradigmatic shifts. Such shifts are precisely a function of "consensus" and "utility" and"objectivity" is a mythical ideal.

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Of course time exists. Why would people complain they didn't have enough of it...if it didnt exist?

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Fresco - "The world is flat" may have been a popular group concensus,
and even a useful concept,

but then we acted on the world some more, and discovered a few more observations about it.

So I guess you're right! "Naive realist" it is.
We are constantly catching up to the things we discover around us.

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USAF,

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Gravitational fields is what bends and curves space-time.

It seems inconceivable to me, that two completely different ideas (space-time and matter) can enter into a relationship if they have nothing in common. That is inconsistent with observation. How much they have in common is the question I'm wrestling with. Do you have any text books to help with this question???

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Did you know that water is magnetic? Weird, huh? Though you wouldn't think a liquid, obviously not metallic, would have any magnetic properties... but it does. It has to do with the bond angles of a hydrogen bond. It forms a bent molecule, making it polar.

Anyway, I think you're looking at this a lot harder than you should. Mass has gravity, the gravity affects space and time.

Have you read "The Universe in a Nutshell" ? There is also "The Elegant Universe" as I mentioned above and another book written by Brian Green but I can't remember the title... They might help you get a handle on it.

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USAF wrote:

Gravitational fields is what bends and curves space-time.

I think it's the curvature of spacetime which we interpret as a gravitational field.

pswfps wrote:

It seems inconceivable to me, that two completely different ideas (space-time and matter) can enter into a relationship if they have nothing in common. That is inconsistent with observation. How much they have in common is the question I'm wrestling with. Do you have any text books to help with this question???

Matter is energy, so I think it's simpler to ask how energy interacts with spacetime.

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rosborne979 wrote:

USAF wrote:
Gravitational fields is what bends and curves space-time.

I think it's the curvature of spacetime which we interpret as a gravitational field.

We've been through this. This idea works, partially, but it not when you look at more specific issues. Look back a few posts and I've explained, confusingly, where this doens't really work well.

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rosborne979,

Quote:

I think it's the curvature of spacetime which we interpret as a gravitational field.

That's my understanding too.

Quote:

Matter is energy, so I think it's simpler to ask how energy interacts with spacetime.

A quibble since we all know E=mc^2, but how is it simpler to ask how energy interacts with space-time? For two concepts to interact (or form a relationship) they must have something in common.

It is a matter of intuition for me that the concepts of space-time and matter/energy are one. USAF seems quite vitriolic of such thinking yet remains to explain why.

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AziMythe,

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So I guess you're right! "Naive realist" it is.

When fresco says "naive realist" he means those who consider their perceptions and conceptions as a representation of something other than what is going on in their mind. At the end of the day, all perceptions and conceptualisations are a mental construct and do not reflect anything other than the world within. The ultimate model of the universe, should one ever exist, I'm afraid, will be a cognitive one and nothing more.

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pswfps wrote:

rosborne979,

Quote:
I think it's the curvature of spacetime which we interpret as a gravitational field.

That's my understanding too.

Quote:
Matter is energy, so I think it's simpler to ask how energy interacts with spacetime.

A quibble since we all know E=mc^2, but how is it simpler to ask how energy interacts with space-time? For two concepts to interact (or form a relationship) they must have something in common.

It is a matter of intuition for me that the concepts of space-time and matter/energy are one. USAF seems quite vitriolic of such thinking yet remains to explain why.

I find myself thinking about things in much the same way you do.

To me it seems obvious that there is an inherent interaction between energy and spacetime. I sometimes wonder if energy itself is merely a compressed (or dimensionally folded) form of spacetime.

I have another thread on Inertia which you might find interesting.

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pswfps wrote:

rosborne979,

Quote:
I think it's the curvature of spacetime which we interpret as a gravitational field.

That's my understanding too.

Quote:
Matter is energy, so I think it's simpler to ask how energy interacts with spacetime.

A quibble since we all know E=mc^2, but how is it simpler to ask how energy interacts with space-time? For two concepts to interact (or form a relationship) they must have something in common.

It is a matter of intuition for me that the concepts of space-time and matter/energy are one. USAF seems quite vitriolic of such thinking yet remains to explain why.

As I pointed out before, you keep saying "to me." But just because something make sense to you doesn't mean it is at all based on reality. I've posted a contrary situation to your idea a few pages back. Go read it again.