# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: clueless on 04/05/2019 14:26:58

Title: Can two infinities cancel each other out?
Post by: clueless on 04/05/2019 14:26:58
Give me a hand, will ya (struggling probably with basics, trying to understand a certain idea, "just asking questions").

Let us imagine a parallel universe infinitely vast, consisting of nothing but space and one chicken egg “in the middle” or where it all started. Somehow, in one nanosecond the egg infinitely enlarges itself, so that the yolk, the yellow internal part of the egg, becomes infinitely big, but also the white which surrounds the yolk; while the shell did not get thicker (like the yolk and the white), rather stayed thin but it stretched to infinity (infinitely big). Now, let as suppose that a dolphin is in the center of this parallel universe, “in the middle” of the yolk. The dolphin starts to swim infinitely fast. Will it travel (instantly) from the yolk to the white, or, since the yolk is infinitely big, would the yolk cancel out the white, so that the yolk’s infinity isn’t compromised? So, will the first infinity (the yolk) cancel infinity that surrounds it (the white) so that the yolk’s infinity does not get compromised? And, will the dolphin reach the eggshell, which represents the edge/border of this parallel universe, and would he somehow be able to break it (even though, evidently, nothing should exist beyond the eggshell)?

And, if space is infinitely big, can this space be perfectly still or it is a rule that it must always be expanding, like space in our universe?

Title: Re: Can two infinities cancel each other out?
Post by: alancalverd on 04/05/2019 14:29:44
In order for anything to move at light speed, never mind "infinitely fast", it needs an infinite amount of energy. This cannot be obtained from a finite mass. So there's nothng to worry about - it simply can't happen.
Title: Re: Can two infinities cancel each other out?
Post by: evan_au on 05/05/2019 22:12:55
Quote from: alancalverd
In order for anything to move at light speed, never mind "infinitely fast", it needs an infinite amount of energy. This cannot be obtained from a finite mass. So there's nothng to worry about - it simply can't happen.
All right then.

So, basically, what you are saying is that, well, Star Trek is lying to us?! Enterprise CANNOT travel faster than light?! Well then. That is not a nice thing to say to a Trekkie, is it now. Not to worry. I forgive you.

Still, since the universe has holographic properties, which can explain many, many phenomenon, could there be an anomaly, like God, who "can" travel faster than light, and maybe even reach an infinite speed? Meh. Forget it.

The discussion on Star Trek has been split off here (https://www.thenakedscientists.com/forum/index.php?topic=76897.0) - moderator.
Title: Re: Can two infinities cancel each other out?
Post by: Bill S on 09/05/2019 18:51:06
As one would expect, Alan’s response is spot on. However, it tends to dismiss all your other questions and speculations, as though they all hinged on the ability of the dolphin to accelerate to “infinite speed”.

Much of the difficulty inherent in the sort of thinking you are tackling stems from the dichotomy in the usage of “infinity”.  Possibly you are thinking in terms of the mathematical use of infinite, which means, simply endless.  No problem there.  Etymologically, there is no better definition of infinite.  Let’s stick with this definition for now.  I’m no mathematician, so look out for mistakes.

Quote
Let us imagine a parallel universe infinitely vast, consisting of nothing but space and one chicken egg “in the middle” or where it all started.

Are you treating space as “something” or “nothing”?  The answer to this may make a difference to the way your thinking progresses.

Quote
in the middle
If your universe is infinite; “middle” is meaningless.  Everywhere is the “middle”.

Quote
where it all started.
The universe is expanding; there is no discernible end to the expansion, so it is infinite.  If you reverse the process, you reach the point where it all started. This fits with our mathematical definition of infinity, but could present complications later.

There’s a lot more in the OP that deserves attention, but how are you (and others) with this, so far?
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 10/05/2019 19:32:07
I'll use the first sentence.
"  Can two infinities cancel each other out?  "
No

Let's put it into signs
Can a minus cancel a minus?

Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 10/05/2019 19:35:15
Philosophically a 'infinity' will be just as big a infinity, whatever you throw at it.
Title: Re: Can two infinities cancel each other out?
Post by: clueless on 10/05/2019 20:10:49
I'll use the first sentence.
"  Can two infinities cancel each other out?  "
No

Let's put it into signs
Can a minus cancel a minus?

But what if one infinity is - and the other +? Got ya! I await my Nobel Prize in Infinities. Actually, and evidently, I'm still struggling. I am currently reading A Brief History of Time though.
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 10/05/2019 20:24:56
Heh. a 'negative' infinity versus a 'positive' infinity?
Kind of like that.

Now you just need to prove it.
Title: Re: Can two infinities cancel each other out?
Post by: Bill S on 10/05/2019 20:45:05
Quote from: yor_on
Heh. a 'negative' infinity versus a 'positive' infinity?
Kind of like that.

Now you just need to prove it.

I think, before you could "prove" anything, you might need to define a negative infinity. :)
Title: Re: Can two infinities cancel each other out?
Post by: Colin2B on 11/05/2019 07:37:38
But what if one infinity is - and the other +? Got ya! I await my Nobel Prize in Infinities.
This one is easy to work out. Start with a distance from where you stand of, say, 1km in one direction which we define as the +ve direction. Now imagine a distance of 1km in the opposite direction, the -ve direction. Clearly they don’t cancel out.
Doesn’t need Nobel thinking.

You can do the same with velocities of 2 objects moving in opposite directions.
Forces would cancel out.
Title: Re: Can two infinities cancel each other out?
Post by: Bill S on 11/05/2019 12:23:05
That makes sense to me, Colin, but the assignment of +ve and -ve to either direction is just an arbitrary decision. There is, for example, no intrinsic difference between 1km North and 1km South.

Isn’t there another way of looking at the “cancelling out” aspect?
If I walk 1km North (+ve), then 1km South (-ve) wouldn’t one have cancelled out the other. I am back at my starting point.
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 11/05/2019 17:37:21
What it brings me back to is relative motion Bill :)
I don't know what it is, but it bugs me. This whole thing of 'infinity's' and relative motion.

I look at it from relativity, and there you have two choices as it seems to me.
Either the definitions we use are a sub species of something else

Or what we see is the way it is.

According to Einstein it isn't.
Title: Re: Can two infinities cancel each other out?
Post by: Bill S on 11/05/2019 21:49:30
Quote from: yor_on
What it brings me back to is relative motion Bill :)
I don't know what it is, but it bugs me. This whole thing of 'infinity's' and relative motion.

I look at it from relativity, and there you have two choices as it seems to me.
Either the definitions we use are a sub species of something else

Or what we see is the way it is.

According to Einstein it isn't.

There really is no problem if you accept that “infinity” is used in two different ways.

1. Call it “absolute infinity” for convenience, if you like. It is all embracing, boundless, changeless and timeless.  Motion, relative or otherwise, has no meaning.  The only thing that prevents this from being just philosophy or metaphysics is that it is essential that something should exist eternally, otherwise there would be no physical world, and no physics now.

2. In our 3+1 dimensional Universe, we need infinity as a mathematical concept.  As long as the way in which we use it doesn’t clash with relativity, Einstein would probably approve.
Title: Re: Can two infinities cancel each other out?
Post by: Colin2B on 11/05/2019 22:59:31
Isn’t there another way of looking at the “cancelling out” aspect?
If I walk 1km North (+ve), then 1km South (-ve) wouldn’t one have cancelled out the other. I am back at my starting point.
Excellent Bill. Philosophers talk in general about the concept of infinity, but physicists and engineers will say it all depends on the situation.
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 15/05/2019 16:49:58
Well, what I do is to take a infinity as a 'infinity'  :)

That means that I don't expect limits inside SpaceTime. I don't expect you to go out to the left to come in to the right.
I call that a limit, and limits presume borders neighboring to something else.  It's Buck Rogers in my mind.

If you instead define what is as connections then there is no end to it.
Title: Re: Can two infinities cancel each other out?
Post by: clueless on 15/05/2019 19:47:22
(...)

That means that I don't expect limits inside SpaceTime. I don't expect you to go out to the left to come in to the right.
I call that a limit, and limits presume borders neighboring to something else.  It's Buck Rogers in my mind.

(...)
Earth has no edge or borders because of its shape like a ball, and yet it is finite. Is it at all possible that, regarding infinity, that it "has" borders, its just  that we can never reach them because they are infinitely far away from us? Imagine a pebble infinitely distant from Earth, teleported into an unimaginably distant point in spacetime by technologically advanced alien race Sipons, of course. Who else? Is infinity, in this case, "distance" that is always the same? If distance of the most distant point of static infinity, relative to Earth, is always the same, then it represents some kind of a border, unless the pebble continues traveling, at an infinite speed, rather than just occupy the same point in spacetime. However, if the universe is constantly expanding, then infinity could have no borders, no edges, if the universe travels at an infinite speed. What you are proposing is some sort of static space, static infinity regarding its farthest point from Earth. This, I am afraid, nobody or very few could imagine, forwhy to be without a border, the universe "must" be "expanding", which cancels static infinity as such, but expanding at an infinite speed - so that the expanding infinity does not get compromised. Static infinity ought to have a border, an edge, while expanding infinity, expanding at an unimaginable, infinite speed, could be the real infinity here.

Am I talking out of my nose, or this, actually, makes sense?

Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 19/05/2019 16:07:31
The way I see it clueless

Don't use geometry.
Geometry is the result
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 22/05/2019 11:48:14
Clueless. Let's use 'time' for defining a universe. Either it exist in a global manner which brings us to a global definition of a time scale for the universe, or it is local as defined in 'time dilation's'. Using a local approach then, does that invalidate a time line? Not locally, but what about this 'global approach' to a 'Big Bang'?

If I by talking about my perceptions of this universe define it locally then my interpretation is unique. It's mine, not yours.
But we share it, and can even (theoretically) share the exact same frame of reference. In which case my time line becomes yours, and yours mine.
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 22/05/2019 11:50:02
Connect this to the idea of 'infinities'.
Suddenly my definition becomes one 'infinity' with yours another.

Although they are equivalent sharing a same frame of reference.
Title: Re: Can two infinities cancel each other out?
Post by: yor_on on 22/05/2019 17:18:26
Collin, the way I read it plus and minus wasn't about displacements in a geometry. It was about canceling the way I thought reading it. I don't really know if that's even possible but you could, if you like, imagine it similar to the way waves can 'cancel' themselves out.. And that was a new idea to me :) looking at 'infinities'