finite or infinite?

[Sikachu]

"Something that is infinite is non-finite. Measurements require finite digits to measure with. Imagine a ruler without finite points. How could you measure anything with it?"

and my reply to that

"A ruler with infinite digits still has numbers on it yes? so there are an infinite numbers placed along the ruler to measure things with.
This conversation is going nowhere and if we keep this up it could go "Forever". So if you were to keep replying to me and I kept replying to you forever there would be no end to it correct? Would that be infinite?"

I don't really care about your pop. philosophy, but your argument about whether things that are infinite are measurable should have involved a comment about numbers. They are infinite in both directions and you can still take a measurement from any one point to any other. Basically you're right and he's wrong.

 

[Jirlond]

Because at each point in existence the universe has a limit - if you constructed a craft fast enough or an instant teleport device you could reach the finite limit. Ever expanding does NOT constitute infinite. The infinite ruler is truely infinite because it does not end, but a ruler that continually grows does have a finite end other wise it could not grow.

My opinion is that something that grows CANNOT be infinite, simply because there would be nothing to grow into.

 

[Embright]

Before this debate gets ANY FURTHER, ask him why in I Kings 7:23-26 it references Pi as being equal to 3 since we are talking physics and math (my specialty) here. Probably why Solomon had to hire Pheonecian artisans to actually figure out how to build the temple.

 

[Eclectic Dreck]

I don't really care about your pop. philosophy, but your argument about whether things that are infinite are measurable should have involved a comment about numbers. They are infinite in bother directions and you can still take a measurement from any one point to any other. Basically you're right and he's wrong.

No, actually it didn't need it. To be infinite all that is required is that it be without bound. Strictly speaking in terms of mathematics, infinity is defined by set theory and you'll find that infinity is difficult to precisely define. Importantly, if you exmaine even the basic notion related to set theory (or just google infinity and click around for a few hours) you'll find that there are many, many kinds of infinity. In this case however, set theory is not actually necessary to examine the problem - simpler mathematics will suffice.

Assume for a moment that you have a point a and b. Rather than placing them in space (which needlessly complicates things) we will examine the problem in one dimension (that is, on a number line). Every second (or other arbitrary measure of time) point A moves in the negative direction (or, more precisely, has it's value decreased) by a constant value (it doesn't matter what this value is) and point b moves in the positive direction (has it's value increased) by a constant value. This is the absolute simplest interpretation of the scenario that was given.

The distance between the two points can be calculated simply enough:

An = x0 + k*a*n + j*b*n

Where An is the distance between the points a and b, x0 is the initial distance between the two points, k and j are the arbitrary constant velocity with which the points are moving and n measures time.

At any finite value of n (that is, with finite time) the result of this equation is a real number. Since we cannot actually do perform math using infinity directly, if one examines the behavior of this equation as n approaches infinity (the mathematical concept of a limit), you will find that the result trends towards infinity.

The end conclusion is simple enough. At any given MOMENT in time, the distance between the two points is finite, predictbable and measurable. This is because this scenario assumes our two points are moving apart at a finite speed. Given infinite time the distance between the two points is likewise infinite because there is no limiting factor to this equation.

There are plenty of examples where infinite time does not yield infinite distance. There is a classic math problem that stumps many. In one step you cover one unit of distance. In your second you cover half the distance of the first step. In the third you cover 1/4 the distance of the first step. If this trend continues which each step covering half the distance of the previous step, how far can you travel given infinite time?

The answer is simple enough - you will travel two units.

 

[Sikachu]

snip

Indeed it did not need it, but it would certainly have been a quick and easy way to demonstrate a point.

I'm not really sure what your long and unrelated explanation is supposed to achieve. If it was general education, then good on you, well explained. If you were trying to teach me something or give me another argument then 'yeah, I know' is my reaction.

 

[Continuity]

On the question of time being infinite you have to bear in mind that time is a dimension of space so its really comes back to the question of space being infinite. Also there is the infinitely large and the infinitely divisible, anything and everything is infinitely divisible in theory but to the best knowledge of science the universe is not infinitely large, its has dimensions, a size, a shape, a limit - yes its expanding but no it is not infinite in size.

 

[paasi]

Time is finite, for though it expands continuously and its beginning is undefined, the current moment is the "end". The continuum of time however is infinite, for it does strech beyond the observable, unless one was to say that time is relevant and when there is no one or nothing to experience time it is no more, but that is a rather Berkeleyish thing to claim.

Of space it is hard to say anything definite, but my belief is that it too is finite, because of how one defines the universe i.e by the further most particle in existence away from the supposed centre of the universe, it does strech, like time, but it is finite so long as it is even theoretically plausible to measure.

 

[slipknot4]

Well, I'd say that the universe is infinite. I mean if there is a border, what's behind it?
That has to be the most correct theory unless:

Prtal to side B(AB) portal to side A​

 

[Continuity]

Well, I'd say that the universe is infinite. I mean if there is a border, what's behind it?

Something else, something other than the (our?) universe, just as beyond our galaxy is something other i.e. more space and more galaxies... who knows, maybe there are infinite numbers of universes outside our own in some other sort of matrix than space time as we know it.

 

[slipknot4]

Well, I'd say that the universe is infinite. I mean if there is a border, what's behind it?

Something else, something other than the (our?) universe, just as beyond our galaxy is something other i.e. more space and more galaxies... who knows, maybe there are infinite numbers of universes outside our own in some other sort of matrix than space time as we know it.

That is not an impossibility, after all. There are too many forces that we don't understand in the universe and the possibility of a 5th layer of dimensions is not impossible.[sup]Height, Width, Depth, Time and [something][/sup]

 

[Dexiro]

I'd say the void that our Universe is expanding in would be infinite.

Nothing else is though, things can be moving towards infinity at most. Time is finite but always moving towards infinity.

Something like that anyway, my head hurts D:

 

[AvsJoe]

Is anything infinite? If so why and if not why not?

Time. Time is infinite. We don't and will never know if there was a beginning or if it infinitely stretches backward (unless you are religious) but there is no reason in my mind that time will never stop; that there will always be at least one thing existing from now until forevermore.

Side note: apparently forevermore is a word. No red squiggly. I thought I was just being artistic. Cool.

 

[YawehG]

Yes, he's right.

The length of the universe/time is measurable in light years.

My physics teacher actually used a very similar balloon metaphor when explaining the nature of the universe to me.

Granted, his metaphor wasn't about the same thing as this, but it is still relevant.

(I think I asked him why mass wasn't being added to the universe if it was constantly expanding. The answer blew my mind and shoved it up my ass.)

The balloon metaphor doesn't work for that, because you ARE adding mass when you inflate a balloon.

 

[Eclectic Dreck]

Yes, he's right.

The length of the universe/time is measurable in light years.

My physics teacher actually used a very similar balloon metaphor when explaining the nature of the universe to me.

Granted, his metaphor wasn't about the same thing as this, but it is still relevant.

(I think I asked him why mass wasn't being added to the universe if it was constantly expanding. The answer blew my mind and shoved it up my ass.)

The balloon metaphor doesn't work for that, because you ARE adding mass when you inflate a balloon.

Not at all - increasing the energy of the gasses in the balloon would result in expansion without adding mass.

 

[goldenheart323]

...

My reply to that

"Just because something can be measured does not mean that it is finite. I don't understand your reasoning here."

Well there's you're problem. Once you measure something, you acknowledge it's finite nature. If the measured distance is 30 miles, it's 30 miles. That's not infinite. If it is, my car should get infinite miles per gallon.
Ok, so to keep with the expanding balloon analogy: Today, the distance from point A to point B is 1 inch. (That's not infinite. Is it?) Tomorrow, it'll be 2 inches. (Still not infinite.) The day after, 3 inches, etc. It has infinite growth, but the exact distance at any given time is still finite & measurable.

What I meant was, say your cars speed is increasing (i know there is a universal speed limit but bare with me) so the speed of the car is increasing and at a certain moment the car is travelling at 30 miles per hour, after that moment the car is travelling faster but the individual moments can be measured.

Speed, distance, volume, etc, it doesn't matter. If you replace "inches" with "miles per hour," it's the same analogy. If you can measure it, it's finite, not infinite. I think you're mixing up the rate of growth with present conditions. In a billion days, the speed would be a billion miles per hour, (like you said, not worrying about the universal speed limit for this example). It's still measurable. The only time speed would be infinite is if you measure it infinite days from now.

 

[goldenheart323]

By the way, for anyone who REALLY wants to explore the nature of the expanding universe, here's a link to a presentation of 4 scientists discussing both this & the multiple universes theories, and even "what's at the edge of the universe?". There's a layman moderator to help keep them from getting too advanced and losing the audience. It's intended for the average person to understand.

http://www.vimeo.com/7102899
That's to part 3 of 6. Part 1 is just some history. Part 2 is about the Big Bang & the initial beginning of our universe & why they believe their theories are correct. Part 3 is when everyone's introduced & the conversation begins. They also discuss the Big Bang, so part 2 is a bit redundant.

 

[YawehG]

Yes, he's right.

The length of the universe/time is measurable in light years.

My physics teacher actually used a very similar balloon metaphor when explaining the nature of the universe to me.

Granted, his metaphor wasn't about the same thing as this, but it is still relevant.

(I think I asked him why mass wasn't being added to the universe if it was constantly expanding. The answer blew my mind and shoved it up my ass.)

The balloon metaphor doesn't work for that, because you ARE adding mass when you inflate a balloon.

Not at all - increasing the energy of the gasses in the balloon would result in expansion without adding mass.

But when you inflate a balloon you aren't adding energy, you're pumping in more gas

 

[KiKiweaky]

Ach my brain hurts :/ I'm truly fascinated by stuff like this though. It really does make you think. OT: I dunno really, both of ye have a good points.

 

[Eclectic Dreck]

Yes, he's right.

The length of the universe/time is measurable in light years.

My physics teacher actually used a very similar balloon metaphor when explaining the nature of the universe to me.

Granted, his metaphor wasn't about the same thing as this, but it is still relevant.

(I think I asked him why mass wasn't being added to the universe if it was constantly expanding. The answer blew my mind and shoved it up my ass.)

The balloon metaphor doesn't work for that, because you ARE adding mass when you inflate a balloon.

Not at all - increasing the energy of the gasses in the balloon would result in expansion without adding mass.

But when you inflate a balloon you aren't adding energy, you're pumping in more gas

The baloon inflates because of an increase in internal pressure relative to the surrounding medium. This can be achieved by adding additional gas certainly. It can also be done by heating the gas (the adding energy bit). Or, one could simply lower the external pressure.