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erkynator OP t1_ixecqs9 wrote

Reply to comment by staticminor in Is space infinite or finite? by erkynator

  1. Nope, Google isn’t based in my house, it’s head office is in California. I live in the UK. And having used it about 5 minutes ago, please don’t be concerned, it still works.

  2. Oh dear. Yes space is a “near perfect vacuum”. Since you seem to have problems with Google, I’ve provided a helpful link What is Outer Space?

  3. If it’s expanding is that because the quantity of matter is increasing (in conflict with the above law) or because things are getting bigger? I know my belly is growing with age, but I’m pretty sure earth is roughly the same size as when I started typing.

  4. I’ll take that as a “NFI”.

Thank you for your contribution!

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Hk-Neowizard t1_ixediux wrote

  1. Space is expanding in the sense that the volume between every two particles (or more reasonably astronomical bodies) is growing. Imagine a grid on a paper. Every intersection is a particle. Now, "zoom in" on one "particle" - look at the distances between all particles compared to before, that's how space is expanding
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erkynator OP t1_ixeef37 wrote

Hmm. So does that mean the forces that keep particles “together” is getting weaker? Why are they distancing themselves from one another? Is the end game in sight when they no longer have any remaining bond and go there separate ways? Sounds like a friends marriage!

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Hk-Neowizard t1_ixetrw6 wrote

Forces aren't getting weaker, exactly. They're just made to act across a larger gap.

One way to thing about it, is to imagine that every point in space "splits" into multiple points all around it (if space is a 3D grid, then every point "splits" into 3X3X3 points centered around the original point). This of course is wrong since space isn't a "thing" that can split, but it's a way to help our limited brains internalize the concept and develop an intuition around it.

Another way to think about it, is to consider force carriers. The photon, for instance, is the carrier for the electromagnetic force. The gluon is the carrier for the strong force, etc. If you're comfortable with the notion of force carriers, you can imagine these carriers are "slowing down". This is a bit more wrong than the previous analogy, because an expanding space mean that not only do "forces take longer to reach" from one particle to another, it also means the force a particle exerts on another is weaker. The analogy, however, helps give a new perspective on the concept of expanding space, so it's worth playing with.

It's important to note that the expanding space isn't really measurable on small scales yet, and won't be for MANY MANY years. The rate at which space is added between two points is proportional to the distance between those two points (again, consider the "splitting space" analogy, the more space, the more "splits" per unit of time), and anything smaller than intergalactic scales is so slow, that the standard-model forces (strong, weak, EM and gravity) all counteract it completely. Only in the vast nothingness of intergalactic space is there enough space and little-enough of anything else for this expansion to be the dominating affect. For now... (if the expansion of space is indeed accelerating)

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Ape_Togetha_Strong t1_ixf80y4 wrote

> It's important to note that the expanding space isn't really measurable on small scales yet, and won't be for MANY MANY years.

The rate of expansion of the universe isn't increasing. It will never increase the space between particles on small scales. That's not what is meant by "the expansion of the universe is accelerating".

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Hk-Neowizard t1_ixgms2g wrote

You're right. It seems I mixed in the concepts behind the Big Rip speculative theory with accepted theories around the expansion and dark energy. I have to go revisit those topic now to separate facts from far-fetched conjecture.

Thank you.

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Resident_Smoothbrain t1_ixegbx3 wrote

It is less that they are being pushed away from each other, but that all the matter in the universe exploded from a single point a long time ago and is still expanding at that same speed according to Newton's first law (nothing to stop it, so it will stay at the same velocity). The particles are just moving at different speeds/velocities and so are expanding away from each other.

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Think of two cars starting a race. One is a very fast car, and the other is a slow car. When they start the race, they are very close to one another, but slowly, the distance between them increases. The big bang is the start of the race, and the cars are the particles.

The particles in any particular celestial object, however, are not distancing themselves from each other. The molecules on earth all hold themselves together and are moving as a single, very large particle moving away from everything else.

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Hk-Neowizard t1_ixeooww wrote

The expansion of space is not the inertia from the big bang. If that were the case it would be slowing down, which evidence doesn't seem to support.

In fact, the expansion is likely accelerating and at a far distant future even the space between protons will expand faster than the strong force can pull them back in.

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