If the universe is expanding

Shaun @ Tru6 · 10-17-2021, 03:23 PM

are there galaxies moving toward us? Since we can't be the center of the universe and we know is it expanding, where is the center?

Bill Douglas · 10-17-2021, 03:53 PM

Quote:

Originally Posted by Shaun @ Tru6

are there galaxies moving toward us? Since we can't be the center of the universe and we know is it expanding, where is the center?

Uranus?

Tervuren · Tervuren's Garage

I haven't studied this in a while, but I recall that the expansion would be similar to upscaling an object.
A 1/18th car model expanding into a 1/12th car model would have the distance between the fenders increase, or the distance from the hood to the top of the windshield, etc...
It would take some form of special action other than the expansion of the universe to have objects coming at us.

LWJ · 10-17-2021, 04:18 PM

You been smokin that green stuff again???

oldE · 10-17-2021, 04:29 PM

A bit simplified but picture if you would a fairground ride with four arms. It is rotating. At the end of each arm are mounted Xs each having riders seated. Each of these Xs are also rotating. There are times when riders are approaching each other and then moving away.
Now think of the seated riders as solar systems within galaxies.

Best
Les

pwd72s · 10-17-2021, 04:38 PM

I can see her as being the cause of things expanding..

Bill Douglas · 10-17-2021, 04:44 PM

Quote:

Originally Posted by pwd72s

I can see her as being the cause of things expanding..

Works for me too.

herr_oberst · 10-17-2021, 05:00 PM

Better stand back, I don't know how big this thing is gonna get...

3rd_gear_Ted · 10-17-2021, 05:43 PM

The earth spins @ 1000 mph.
It travels @ 67,000 mph around the sun
Our galaxy is traveling 448,000 mph around the center of Milky Way.
We are all in motion

Por_sha911 · Por_sha911's Garage

Lets really make heads explode. Study Quantum Physics, Bell.s Theorem of quantum entanglement, and a rift in the space time continuum.
Get back to me when you got that all figured out.

Sometimes the correct scientific answer is there is no known answer that doesn't require faith.

Pazuzu · 07:35 PM

Quote:

Originally Posted by Shaun @ Tru6

are there galaxies moving toward us? Since we can't be the center of the universe and we know is it expanding, where is the center?

First off, space is expanding in the 4th dimension (not time...), so it's not at all intuitive how it is moving to our 3-dimensional brains.
That being said, one of the classic thought experiments to explain it is raisin bread. A loaf of raisin bread expands as it bakes in the oven. Any raisin looking at any other raisin will see them all moving away, so they all think that they are the center of expansion, but in fact the outside observer sees that there is no real center of expansion, no raisin is more important than any other.

The other fact is that things are not moving away from each other, but the actual fabric of space-time is what is expanding. You and I can stand 2 feet apart from each other, then not move for the next billion years. We will STILL be two feet apart from each other, but the "foot" will have stretched several times, and we will now be across the room from each other.

Think of a larger rubber band, maybe 3 or 4 feet long. Draw a bunch of marks on it to separate it into 100 segments. Now, place an ant in each segment. Each ant can see how far each other ant is, and can see how far apart the segments are, but in general, they are living a 1 dimensional life (they can only move forwards or backwards). Now, take that rubber band and pull it from the two ends.Pull, pull, pull until your fingers are twice as far apart. Each ant would have seen all of the other ants move away, and how far they moved would be based on how far they were to begin. HOWEVER, even having seen the next ant move quite a bit, it would also see that the next ant didn't cross any of the drawn lines...in fact, despite appearing to be much further away, as far as the ant knows, the next ant is still 2.5 segments away.

As the ants see, space expanded, but so did their measuring sticks, and every ant expanded from every other ant. How? Because you expanded their 1 dimensional world in the SECOND dimension. When you do that, things act weird.

WE are in a 3-dimentional universe, which is expanding in the 4th dimension, and therefore we see weird things. Everything is moving away from us, but from everything else as well. Things don't grow in size as the universe expands, because the measurement scale tied to space-time itself is also expanding.

That, or Por_sha911's claim that there are no answers without faith.

GH85Carrera · GH85Carrera's Garage

Think of a spotted balloon getting inflated. Every spot will move away from each other. No matter where the spot you pick to watch, every other spot will move away.

sc_rufctr · 10-17-2021, 07:33 PM

Thanks... I'd never heard of the "Hubble Sphere" before.

red 928 · 10-17-2021, 08:43 PM

the universe isn't expanding time is slowing down and we use time as a measure of distance so it seems like things are getting farther away but they are not

Arizona_928 · 10-17-2021, 09:48 PM

Would it matter? Speed of light and all that quantum jazz.
We'll be long dead.

Tervuren · Tervuren's Garage

If you ever want to improve your idea of the scale of this galaxy give this game a try.
It plugs in all our known data, and then uses procedural generation to fill in.
Even making leaps between stars in a handful of seconds the milky way be big place.

https://www.rockpapershotgun.com/elite-dangerous-expedition-diary-part-3

ckelly78z · 10-18-2021, 02:48 AM

I would let her explain things to me anyday !

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by Pazuzu

........... no raisin is more important than any other.

Keep this socialist viewpoint in PARF, please.

This stuff hurts my head.

Two galaxies moving apart faster than the speed of light but physical things can't travel the speed of light. So it's the fabric of space and time.

I think you need to deeply understand the math before you can come close to thinking you understand what is understandable at this time.

hcoles · 10-18-2021, 04:23 AM

There was a TV show on this yesterday.
Galaxies can move away at or near the speed of light because the space inbetween can expand faster than the speed of light.

Crowbob · 10-18-2021, 04:40 AM

Two objects traveling away from each other each at the speed of light means they are traveling at twice the speed of light. In other words, object A is moving away from object B at twice the speed of light and vice versa.

That’s the relativity part. The objects are moving relative to each other at twice the speed of light. But relative to their starting point, each are moving away from it at the speed of light.

However, if you have infinite starting points with infinite objects moving away from them, nothing is moving at greater than the speed of light. Yet, even though one edge of the universe is receding from the opposite edge at infinite multiples of the speed of light, because time relative to the object slows as that object approaches the speed of light, as the universe expands it takes proportionally longer to travel greater distance so that at some point in space-time, nothing is moving yet the universe is expanding.