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How different are the two ages? Like is we consider position does it change significantly if we don’t use Newtonian gauge?

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Yes. If you look here you will see the relative "potential" for corrosion of different types of metals. The further apart they are in the chart, the more corrosion there will be.

> objects at the far edges of the universe are actually travelling at constant velocity from their reference

That's the neat trick - they are not traveling at all! Expansion of Universe is happening because space between everything is growing, not because something is flying away.

Closest analogue would be - draw two points on a balloon and start inflating it. Distance between this two points would start to increase without them moving by themselves.

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It continues to travel through space towards us but the space expands to fast for it to "catch up". Unless something is tightly enough connected to counteract this, it will happen to everything separated by space. The current models even predict that in the far future, the only information available will be that from the local cluster of galaxies. The space between our cluster and the other ones will, although it is relatively small today compared to the visible universe, expand at a faster and faster rate. 1 unit of space becomes 2 units of space in some time, then 4 units of space, 8 etc...

We are actually fortunate that we may observe light all the way back to where it started! The "observable horizon" is still behind the beginning of time, so to speak.

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More or less the same composition but the material is denser, yet full of hollow spaces and struts. They tend to break quite jaggedly compared to mammalian bones, but are usually harder to break.

They’re totally evolved for flight.

Corrosion also requires an electrolyte to provide a path between anode and cathode. So if kept in dry air these parts would experience little to no corrosion. If submerged in sea water the corrosion rate would be higher.

Could you measure voltage difference to get a guideline?

Don't forget, depending on the steel, it can be its own galvanic cell. Fe2O3 and Fe3O4 are just different enough to make a anode-cathode pair.

Is the edge really 90 billion light years away or just 45? For some reason I was thinking 90 sounds more like the width

When people say “the edge of the universe” they actually mean “the edge of the visible universe”. Why? It’s a combination of the (constant) speed of light and the rate that objects (galaxies for this example) fly away from each other in the universe.

Say a galaxy beside us is moving away at 2 kilometres (we’ll use km, 1000m, instead of miles as miles doesn’t really fit in with science very well) per hour, then another galaxy further on is moving at 4 km per hour from our viewpoint in galaxy 1. Galaxy 2 sees both galaxy 1 and 3 moving away from it at 2 km per hour, and galaxy 3 has a similar view to galaxy 1, but for it it looks like we’re the ones travelling away from it at 4 km per hour.

And as these galaxies move away from each other, that 2 km/hr is no longer true, and speeds start to get faster and faster.

So objects in the universe are not just moving away from each other, they are also accelerating away from each other.

Now let’s take that logic and take us thousands of km/ph, then millions of km/ph, then billions of km/ph, and beyond…

Then we get to the speed of light. The speed of light per second is easy to find but gets even more massive when talking about light in km/hr.

1.08 x 10 to the power of 12 km/hr or 1,080,000,000,000 km/hr

That’s a trillion km/hr. And we’re now at the edge of the visible universe - 46.5 billion light years away.

When objects are flying away from us an inch / cm / etc faster than that, we will never see them again. And of course, that object is continually accelerating, so of course it is going faster than that already.

And why don’t we see them? If an object is moving away from us faster than the speed of light, then the light emitted by that object will continue to be emitted, but it will never ever reach us … it didn’t and it can’t go fast enough.

What we see as things get closer to the edge of the universe is that they get massively red shifted, then when they get to the edge, it’s a bit like a black hole - things will appear to get fainter, then as they approach and cross horizon, they will infinitely slow down and appear to stop, then fade away. Or I assume they can’t fade completely, so all objects that ever passed the horizon will be visible on it, just incredibly faint, and effectively gone.

That galaxy that has just sadly disappeared from our view is … ok (or at least it wasn’t affected by a visual effect only experienced by us). That galaxy will have it’s own visible universe, and has just seen our Milky Way slow down, stop, and get continually fainter. And similarly, every object in the very likely infinite universe (very likely, as we can’t observe it for ourselves, snd never will) will experience it’s own individually experienced visible edge of the universe.

Over time, we will see more and more galaxies travel over that horizon, and one day in the far flung future, we’ll not see any other galaxies or objects outside of the milky way (or Milky Way and a few other galaxies linked together by a gravitational force stronger than the expansion rate - these galaxies including the milky way are known as the Local Group). Beyond the stars of the Local Group, it will be dark, and it always will be.

Will that force pulling apart galaxies impact the galaxies themselves - will galaxies be destroyed as stars find that expansion force to be higher than the gravitational force acting on them?

The current theory here is that the expansion rate isn’t big enough for that to happen, but scientific debate changes - or is enhanced - in this field all the time. It’s really interesting stuff!

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You’re looking at now, sir. Everything that happens now is happening now.

What happened to then?!

We passed then.

When?!?

Just now.

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