# Space-Time Relativity

1. Jul 6, 2015

### Topleft

If time and space are relative, then if the amount of space is finite, is the amount of time finite? Is it possible to measure the amount of time for a given space?

2. Jul 6, 2015

### phinds

There is no such thing as "the amount of time for a given space". It doesn't work like that. I think your concept of what "relativity" means is confused and I recommend that you do some reading on the basics. Start with special relativity.

3. Jul 7, 2015

### Finny

Presumably you are defining an an arbitrary finite volume or length and wondering about the time in such a finite space.

Give that question some thought: Has your definition of such a finite volume for inspection changed the volume in any way? What about the time 'surrounding' that finite volume...has it changed in any way? Has the time within that finite volume changed in anyway?

Otherwise, in our universe, we have no evidence space is actually finite...although it's possible.

Hope that helps clarify your thinking.

Further, that 'space and time are relative' refers to the fact that different observers may make different observations because their space and time may be mixed together in different combinations.

How about the two blind men inspecting parts of an elephant: one finds and big thick trunk, the other a skinny tail? Who is right? Another simple example of how observers may see 'space', size, differently are the different perspectives of an observer close to a house [house looks big] and that of a distant observer [house looks small]. Who is 'right'?

Until Einstein, scientists did not understand that space and time are part of a common and related continum. Your space and your time may be different from mine. THAT was a revolutionary scientific insight.

4. Jul 7, 2015

### ZapperZ

Staff Emeritus
There is a flaw in your logic here, and I can show this by coming up with a simple example.

Let's say you have in infinite square well, a very common example in many textbooks. The "space" here is in between the two boundaries of the well, so it is "finite". I can solve for the standing wave that fits into that space, and get an infinite series, in principle, of solutions that can exist within that space.

So already I have an example where a finite space does NOT imply an automatically finite behavior of other properties.

Whenever you come up with a scenario or question such as this, you must also include a compelling argument on why it is so. In this case, you need to come up with not only a compelling argument on why one property must mimic the property of another, but also supply an "example" that support your argument. Otherwise, you are engaging in a fishing expedition.

Zz.

5. Jul 8, 2015

### Topleft

I am lost as to how the space of an infinite well is finite. However, if you are stating a basic fact that of two relative quantities one can be infinite, and the other finite, then you are challenging my definition of the word relative. I am still lost, please help.

6. Jul 8, 2015

### Staff: Mentor

Your best bet will be to follow the suggestion that phinds made in post #2: "do some reading on the basics. Start with special relativity". That way you'll be able to see how space and time work together.

There are a number of good presentations on how special relativity works that require no more math than high school algebra. Find one of these, and get going....

I'm closing this thread - an internet forum isn't the right place to build a foundation, although we can help you with specific problems that you may encounter as you try to learn SR.