Ennara t1_j1e1akv wrote
Reply to comment by a4mula in Can we truly know the age of the universe? by Geodad478
>the space between galaxies is expanding at a rate that is faster than the speed of light. However, it is important to note that this expansion is not a violation of the laws of physics, as it does not involve the movement of matter or energy through space.
Oh god, this breaks my brain. The amount of space between galaxies is expanding, but the galaxies themselves aren't moving as a result of the expanded space between them? I'm not saying you're wrong, but god dang I can't wrap my head around how that's actually possible.
The only vaguely coherent thing I can think of is like... a piece of taffy, where the two galaxies are sitting on the edges and you stretch the middle downwards. So the amount of space the taffy occupies increases, but the galaxies don't actually move. But I don't think that's accurate, because if space between us and a distant galaxy is expanding, then the distance increases which it doesn't in the taffy explanation... And I'm back where I started.
a4mula t1_j1e1s1h wrote
If you read the earlier analogy with the cake.
We can pretend, because its just an analogy. That space in the analogy is air in the cake.
The molecules of the cake aren't growing or moving. It's only that the air in between them continues to grow.
It will ensure that the cake molecules end up with greater distance between other cake molecules.
But it's not because the cake molecules moved. It's because the air in between them grew.
Now this is just pretend, because air is not space. Air is molecules too. So I don't want to confuse that.
But it does fit the analogy.
Ennara t1_j1e40x2 wrote
Yeah, I sort of get that, I think at the core of it all I'm just having trouble wrapping my head around the concept of increasing the amount of space between two objects without moving them. Using the cake analogy, I'm finding it difficult to understand how the air molecules move in such a way to take up more space without pushing the things that already occupy that space out of the way. I can accept that they are based on the studies and testimony by people far smarter than I am, but my brain is pitching a fit because I'm struggling to grasp the 'how.'
a4mula t1_j1e5iic wrote
That's okay. I mean these are Big topics. It's taken our species millions of years of slowly building up to this point right now that we have the understandings we do of them.
It's not easy. For anyone. Not for you, Not for me. Not for Einstein.
We're not born innately knowing this, we're educated about it. If they are concepts that we find interesting, perhaps we consider them. It's only through this education and consideration, not just the education itself, that we come to understanding.
Not everyone has the time or inclination to consider these topics, and that's okay.
But for those that do, understanding will grow in some type of correlation between the interactions of the education and your consideration of.
Ask for analogies, they're great tools of abstraction. It takes these difficult concepts out of the realms of mathematics, and puts them squarely into terms we can better understand, everyday language. Math is important, but if it's not a language spoken by us, it's not helpful.
Einstein's brilliance was never that he was a great mathematician. It was his ability to break down very complex thoughts into stories he could understand.
a4mula t1_j1eafan wrote
I wanted to add another reply here.
What If I wanted a really cool expandable cake like we talked about and asked you to make it for me.
But I've got a very special request.
After you bake the cake and add the frosting. I'd like to add a special flavoring. So that anyone can make this cake taste the way they'd like.
See if you can figure this out. Can I do this? What do the actual interactions look like? If I dropped the flavoring into one part of the cake, how would it distribute?
Would it be evenly? Could it ever fill the entire cake, assuming the cake never stopped growing? How would it travel from one cake molecule to the next?
This will help you to understand concepts like speed of light, and why we can't pass information faster than it.
It'll help you to understand localized events and how they interact with portions of the universe, but never the entirety of it.
Think about the relative movement. Without the flavoring now. The space between two cake molecules will always be a different relationship depending on the location of where they exist in relation to one another.
Two cake molecules side by side will always experience the same relative separation. But two molecules separated by the entire cake will always experience greater total separation because all the spaces of molecules growing in between them are cumulative.
We can pass flavor between two cake molecules, indefinitely. But assuming the cake never stops growing, what you'll find is the ability to spread the flavor becomes a function of the overall growth rate of the cake as a whole, meaning it can never keep up and that the total amount of the cake that is flavored in respect to the total cake, will always decrease.
That's odd. Because we're still getting more cake that is flavored. It's just that the amount we get will always represent a smaller percentage of the whole.
edit: We've taken our analogy in a very specific direction. One of infinite inflation of a mostly spherical object. Our universe doesn't need to meet those criteria. This is just one way to consider things. If the universe has different parameters, the interactions would inherently be different. What if our cake was really a doughnut? What if it were just a 2d plane of 3d information?
Keep these things in mind, as there are clear limitations to locking our thoughts into the ability of analogies to represent ideas.
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