If the universe is expanding
 

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?

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Uranus?

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.

You been smokin that green stuff again???

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

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

Works for me too.

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

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

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.

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.

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.

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

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

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

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

I would let her explain things to me anyday !

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.

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.

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.

I have read and studied this stuff for years and years. Hawking and Feynman are prominent in my library. After all that study I've concluded that my ape brain isn't able to grasp the reality of it. So I peer through my telescopes in awe of it all and I am grateful for never having lost my ability to just observe and say "wow".

Hear, hear, flatty!

I consider the greatest gift ever having been given me is the gift of appreciation.

She's been a great presence online for years - but this is deeper stuff. Very enjoyable...

"Modern Physics" brought me the worst experience of my 7 or 8 university years. Relativity and the whole time/distance thing blew my mind and I still don't understand it. I'd like to think that I'm a sharp crayon but, wow, I got 18% on that test. Things looked up when we got to solid-state stuff. Fermi I got, Einstein I don't...

I reduce everything to magnets. It’s all magnets. The answer is always magnets. That weird feeling of repulsion when pressing two magnets together has been the most baffling sensation, well second most baffling sensation, so far in my life.

Locally yes, globally, no

watch this for a better and fuller explanation
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I am in love.

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Thanks Bill, will watch tonight.

With regard to the discussion of particles I'd like an answer, in laymans terms to this question. When a researcher declares that a new particle has been discovered how do they eliminate the possibility that it's simply a fragment of another particle?

When you see those images from CERN there are many traces caused by bits and pieces. The curvy traces are particles carrying a charges, the straight lines are described as non charged particles.

So the non charged particles may be fragments, but might not they be neutral whole particles?

I gots questions.

According to the Standard Model, which is the best description of what is known as of today, these are the known 17 fundamental particles. They are organized in columns, each of which is a family. The far left column or family is what makes up the everyday matter we com in contact w/. The 4th column made of Bosons is the force carriers, top to bottom gravity, electric, weak nuclear and strong nuclear, the far left Higgs boson which gives them all mass
https://www.quantumdiaries.org/wp-co..._-1024x768.jpg

another way to look at them is this, Quarks are what make up the Nucleus of matter and are confined to the nucleus by the Strong force, Leptons are found in the atoms shells when electrically bound and zip around freely otherwise, again the Bosons or force carriers are on the right and the Higgs providing Mass in the middle, again everyday stuff is the far left column
https://cds.cern.ch/images/OPEN-PHO-...ile?size=large

Interesting contribution on this just published: 94% of all galaxies in the visible universe unreachable. .. unless one can travel faster than light... very well written article with great diagrams...

https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94%... I might be lost but I'd say it's a much higher percentage that are unreachable. The closest galaxy to us is Andromeda and its 2.5 million light years away. So, at the speed of light, which we can't reach, it would take 2.5 million years to get there. That would be one hell of a space craft to make such a journey. Yeah, 2.5 million years of human evolution on a space craft, lol.

The closest Star to us...Proxima Centauri...
The Voyager 1 spacecraft is on an interstellar mission. It is traveling away from the Sun at a rate of 17.3 km/s. If Voyager were to travel to Proxima Centauri, at this rate, it would take over 73,000 years to arrive. If we could travel at the speed of light, an impossibility due to Special Relativity, it would still take 4.22 years to arrive!

Eric, do you really believe that humans are evolving?
What I see is knowledge is being passed down and not having to be gained anew.
Our knowledge is evolving.
But humans?
What is our DNA doing?

It's beautiful to see how poetic, artistic, our supercluster is. Makes perfect sense to me. but you can tell you it's only a piece of a whole. Like a section of a Jackson Pollock painting. But different.

We are evolving to be able to sit and look at a screen for 10 hours a day. Then the remaining time looking at a cellphone.

Some how I missed the evolutionary train on that looking at a cellphone thing.
I had one of the early smart phones pre Iphone.
When the Iphone came out it was too much $$$ for my youngself to afford to keep up and meet my life goals.
Then eventually I observed the way people with Iphones changed.
And went, nop, nop, domed.
Not the same for everyone, some make great business use out of them.

its just a plot to get more property tax out of us as our property expands.

here's an even broader and more detailed look, be sure to watch the animation at the bottom, The scope is breathtaking

https://www.smithsonianmag.com/smart-news/a-new-3d-map-of-the-universe-covers-more-than-100-million-light-years-753656/

Yes, humans continue to evolve, as do all living species. Evolution is not something that happens at a time rate that humans, or any animal can relate to on a day to day basis. It takes millions of years to make changes, not just a few generations or a few hundred years.

3.2 million years ago our ancestors were like Lucy.

https://en.wikipedia.org/wiki/Lucy_(Australopithecus)

1.2 million years later the first Homo erectus evolved from the ancestors like Lucy.

https://en.wikipedia.org/wiki/Homo_erectus

This sounds good - I was following until "nothing is moving yet the universe is expanding".
The TV show I mentioned above was exploring this subject as it relates to finding other life or other life finding us.

I just can't imagine a universe without life on other planets. It is just so far to the next star and unimaginable distances to the next galaxy that I can't image we will ever be able to communicate with them, much less have a visit from them, or travel there.

I know all the old saws, about how people all believed that traveling faster than 35 MPH was impossible when the horse was the fastest mode of travel. Unless Einstein's theories are finally proven wrong, it just can't happen. Everything keeps proving Einstein was right. There was no math or testing the theory abut faster than a horse travel was impossible, just like thinking going to the moon was just impossible.

I honestly hope to live long enough to discover life on Mars, but I doubt I will live long enough to ever know if there is life in other solar systems.