The speed of our Universe?

[rigney]

How fast is our universal speed? From where are we coming, and to where are we going? I've heard everything from, it isn't moving at all; to light speed, or greater, then to slow down and freeze over??? Since I'm not well enough equipped to even begin answering such a question, maybe someone can help.

Edited June 16, 2010 by rigney

[insane_alien]

relative to what?

 

there is no universal frame.

 

relative to ourselves, we aren't moving.

[rigney]

Well Insane guy, we know that something is happening? I awake in the morning, it's light and it's about seven AM. I go to bed around ten/ten thirty PM each night when it's dark, I sleep about eight hrs and do it all over again. I go through the four seasons and recognise the difference between them. Science tells me that our earth is spinning at a thousand miles per hr. and we're zipping around our sun at some sixty five thousand miles per hr. I'm not sure that I can relate to no universal frame since I don't know what that means. Some folks say that our universe is traveling at the speed of light which makes me wonder? Why is there no universal frame? I'm told that our galaxy and the Andromeda are gonna crash into each other somewhere down the road. Something has to be moving?

[vordhosbn]

Why is there no universal frame?

In everyday life, you are used to having a concept of universal movement. Things either move or remain stationary.

However, it's important to realize, that this motion or movement in our daily activities, is actually a relative movement to the Earth. Which is the same as saying movement in the reference frame where Earth is considered stationary. Earth may be orbiting the Sun, and together with it - orbiting the galactic core, but it is experiencing no significant acceleration, which is something you can feel (and detect). So you don't feel the Earth moving, because it's moving at somewhat constant speed. For example, when you are in a train, you don't feel it moving if it is not speeding up or slowing down.

There is no cosmic matrix to which, we can measure our speed. We can say - relative to the Sun we move with X speed, relative to the galaxy core, we move with Y speed. But we can't say we move with this absolute speed, because there is nothing that is absolute.

 

P.S. It's true that Andromeda and the Milky way will intersect with each other, but due to the enormous vast distances between individual stars, it's unlikely that there will be much "crashing".

Edited June 17, 2010 by vordhosbn

[ajb]

You could consider the comoving distance to a distant galaxy dived by the cosmological time i.e. the age of the universe. That would give some measure of velocity. I think this is the one that cosmologists would quote.

 

If you do this you find there are galaxies that are moving faster than the speed of light away form us. But this is not in violation of relativity and is of course coordinate dependant.

[vordhosbn]

Interesting, I was unfamiliar with comoving distances, and the comoving observer concept, the "Hubble flow", etc...

But I wonder - if you average in some way the vectors (or tensors*) of movement for all "lumps of matter" in the observable universe, you will get one pretty [math]\vec{0}[/math]? Is this correct?

 

* ajb, if I understood correctly one post of yours - tensors are more elegant way to facilitate relativistic calculations. However I don't think I have understood them very much and so feel free to correct me about it.

[ajb]

* ajb, if I understood correctly one post of yours - tensors are more elegant way to facilitate relativistic calculations. However I don't think I have understood them very much and so feel free to correct me about it.

 

Vectors are a "species" of tensor, so don't worry.

 

I guess you can do some kind of averaging and end up with a speed.

[Spyman]

Velocity

 

In the general sense, the absolute velocity of any object through space is not a meaningful question according to Einstein's special theory of relativity, which declares that there is no "preferred" inertial frame of reference in space with which to compare the object's motion. (Motion must always be specified with respect to another object.) This must be kept in mind when discussing the Galaxy's motion.

 

Astronomers believe the Milky Way is moving at approximately 630 km per second relative to the local co-moving frame of reference that moves with the Hubble flow. If the Galaxy is moving at 600 km/s, Earth travels 51.84 million km per day, or more than 18.9 billion km per year, about 4.5 times its closest distance from Pluto. The Milky Way is thought to be moving in the direction of the Great Attractor. The Local Group (a cluster of gravitationally bound galaxies containing, among others, the Milky Way and the Andromeda galaxy) is part of a supercluster called the Local Supercluster, centered near the Virgo Cluster: although they are moving away from each other at 967 km/s as part of the Hubble flow, the velocity is less than would be expected given the 16.8 million pc distance due to the gravitational attraction between the Local Group and the Virgo Cluster.

 

Another reference frame is provided by the cosmic microwave background (CMB). The Milky Way is moving at around 552 km/s with respect to the photons of the CMB, toward 10.5 right ascension, -24° declination (J2000 epoch, near the center of Hydra). This motion is observed by satellites such as the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP) as a dipole contribution to the CMB, as photons in equilibrium in the CMB frame get blue-shifted in the direction of the motion and red-shifted in the opposite direction.

 

http://en.wikipedia.org/wiki/Milky_Way

[rigney]

Guys, if you've looked at my initial question, you'll know that my total understanding of physics pertains only to x-laxs. No pun or insult intended. Math of any sort is not my thing. But could it be possible that the entire galactic universe might be moving at less than a million mph? It's a foolish guesstimate and only a question, so I have no way of explaining it other than how I relate it to our galaxy and solar system, which I don't do too well either.

Edited June 17, 2010 by rigney

[Spyman]

rigney, I think it would be helpful if you explain what in your opinion the "entire galactic universe" consist of...

[rigney]

rigney, I think it would be helpful if you explain what in your opinion the "entire galactic universe" consist of...

 

Thanks Spyman. My understanding of the universe is that several (13+?) billion years ago everything eminated from a specific point. Over time it has somehow evolved into the galaxies we see today. While what we see is perhaps only a sampling of this vastness, I believe that in any portion of the universe we might ever look, the view will be no different. My problem is that, with red shift; we see the fartherest galaxies moving away from us at light speed or greater. Yet the galaxies in our immediate cluster or those in nearby clusters, don't seem to differientiate spectorally in speed at all? If as Einstein formulated, we exist on the outer cover of some expanding sphere where gravity, time and space warp(age?) act as a continuous circle, from what is the universe running, and to where is it going at such a speed?

Edited June 17, 2010 by rigney

[ydoaPs]

The answer to the speed of the universe is really whatever you want it to be.

 

Zoom out from the universe billions of trillions of googleplexes of lightmillenia until you can 'see'(due to the speed of light, no one vantage point will be able to see the entire universe until long after it's gone) the whole universe. Now, what can we tell about its motion? We can see that the individual parts that comprise it are moving away from each other; it is expanding. But that's not the motion I think you were asking about.

 

Is it moving in a certain direction? Well, as I said, it is if you want it to be. Motion is defined by the frame of reference of the observer. There's not natural frame against which we can say whether the universe is moving(the universe is, after all, everything), but we can imagine such a frame as being you somehow stuck way out in our imaginary point discussed earlier. Now, this point can be chosen to be at rest with respect to the universe, but that's not relevant to our discussion. Are you zooming past the universe, or is it drifting past you? That depends on if you take the frame of you or if you evaluate the situation from the frame of the rest of the universe.

 

So, in essense, the answer is whatever you choose. The concept of motion is meaninless without something against which to measure.

[Cap'n Refsmmat]

I think the idea of reference frames is best illustrated by this video, and I'm not kidding:

 

akLC_JMjpjA

 

For a moment you think "oh, the train's moving." But it's not. Why? Because we measure velocity by comparing one object to another object. (A car vs. the ground, for example.) So when you compare train vs. station, you see the train moving -- but it might just be the station moving too.

 

For the universe, what do you compare against? Another universe? There's nothing to compare the entire universe's motion against, because it's everything.

[rigney]

I suppose if one was to look at either scenario and acquiesce to it as a creed, it might be conceded as an ediface to ignorance. I simply can't go there. I see things that I can touch, feel, visualize and/or calcuilate as real, not the thought processes of others. My own ideas of where, and why we are; may not be in accordance with many good and much more educated folks than myself, but unfortunately I've never been a very good follower. My question was and still is: As we seem to languish in our little corner of the universe, why does the rest of it seem to be running away at light speed? And to where? Bless his little Pea Pickin' Heart, but Dr. Einstein surely did put a burden on the rest of us???

Edited June 18, 2010 by rigney

[Baby Astronaut]

I think the idea of reference frames is best illustrated by this video, and I'm not kidding:

That's a really great example. I'll definitely be using it to explain frames.

 

As we seem to languish in our little corner of the universe, why does the rest of it seem to be running away at light speed?

New space is being created everywhere in the universe, meaning objects that are distant will be even further away by tomorrow, next day, etc. So if you add up all the new space between us and a distant galaxy, then the more further away the galaxy, the faster it's going to recede from us. After a while, the speed it recedes becomes greater than the speed of light.

 

Also, to viewers from that galaxy we'd be receding at faster than light.

 

But galaxies closer to us don't recede because our combined local gravity is stronger than the expansion.

[jackson33]

...

[rigney]

How can we possibly gaze at something so vast as the universe and think of it as making any sense at all? And since there are no mile markers or sign posts to compare with other galaxies, we are left to our own designs in making up the rules. With that said, let me make mine.

Scientist's can analyze and measure the "mean" axial and orbitals speeds of each moon and planet in our solar system and their journey around the sun, down to the nth degree. And also, our solar systems path around the galaxy. Add any of these mean speeds to the galactic revolution of our Milky Way, and we might find that our universe is moving at approximately 666,000 mph., vectorially. The equation may be a simple: A+B+C=D, with D being this vectorial constant.

I can't refute any of your analagies simply because I don't have the answers. But in checking out our solar system, it seems rather uniform and follows some basic rules. Like, all of the planets and their moons rotate in a counterclockwise fashion, other than a couple drifters who run contrary to the scheme. Even our sun and galaxy follow this example and rotate likewise. Would it not seem likely that other galaxies would do the same? When "we do" eventually explore other solar systems, I believe they too will be similar in design and calculable in comparison to their rotational speeds and distances from their suns, much as our system does. Quite possibly these rotational speeds of our moons, planets and galaxy are caused by a specific constant, and that being, the vectorial prolongation of our universe! Don't laugh, I have a mean dog and if he had teeth, he'd bite you for doing that!!

Edited June 18, 2010 by rigney