Physics is all a hoax!

[Bugs ****ing Bunny]

This is confusing. Can't we all just hug and agree that it's because Jesus loves us?

[Ben Kenobi]

It's just turtles all the way down.

[Lorizael]

Then we just need to contract the universe until Alpha Centauri is just a Sunday afternoon drive away.

That is the benefit of relativistic travel.

[Elok]

This is confusing. Can't we all just hug and agree that it's because Jesus loves us?

Theologically speaking, this can be used as the reason for everything. Not very detailed, tho'.

[Sava]

Ben knows even less about physics than he does Christianity.

[ZEE]

be cKareful, Spec, I am the Chat-Lordâ„¢ remember? lol.

[MikeH]

From the point of view of the observer on one of the objects. From an outside observer, say perpendicular to either, the actual physical distance between the object would increase twice as fast. This is also why they tend to use a coordinate system that remains static by comparing the ratio of the distance between the two.

But in the case of universal expansion how do you get an observer 'outside' the universe to observe it's expansion? All observers you can choose would be part of the expansion and see the expansion moving away from them at at most c.

[MikeH]

Anyway someone above said it - that's missing the point - things in space can't move faster than light, but space can expand faster than light.

So some galaxies that we can see (well we can see the light that they emitted billions of years ago) are moving faster than the speed of light away from us now. But their light can't come towards us faster than the speed of light, so at some point they'll move outside our observable universe.

[Ben Kenobi]

But in the case of universal expansion how do you get an observer 'outside' the universe to observe it's expansion? All observers you can choose would be part of the expansion and see the expansion moving away from them at at most c.

Which is why we have things like blueshifts and redshifts...

The hypothetical 'outside the universe observer' perpendicular to the expansion would observe them receding at twice c. This is what I meant by a 'non-inertial frame of reference'.

[MikeH]

1. Observer outside the universe is meaningless
2. That's still not the reason explanation of why the universe is bigger than it would be if it expanded at c.
3. 46 / 13.8 = 3.333

[Ben Kenobi]

1. Observer outside the universe is meaningless

Not at all. The only way a concept of 'unobservable universe' even makes sense is coming from this perspective.

2. That's still not the reason explanation of why the universe is bigger than it would be if it expanded at c.

Well true, that's what the Hubble law is all about.

[MikeH]

Not at all. The only way a concept of 'unobservable universe' even makes sense is coming from this perspective.

Unobservable universe refers to the bits of the universe we can't see because they are further away from us than the distance light can travel in the age of universe.

That doesn't mean they are outside the universe. The concept of something outside the universe isn't meaningful.

[MikeH]

Well true, that's what the Hubble law is all about.

No it's isn't.

[Lorizael]

I'm not sure why you're bothering with this, MikeH. The only people that are ever going to see this thread already know that BK is a non-sequitur machine.

[MikeH]

Boredom.