DawgTalkers.net Forums DawgTalk Everything Else... Question for the space/universe peoples

So we all know the earth moves around the sun super fast, like 98,000mph. Our solar system moves around the center of the milky way, at something like 200,00 mph. Don't quote me on those numbers. That being said.

Are there objects in the universe that don't move at all? I was thinking about this today, I think the answer is no, because the universe is expanding and everything seems relative to each other. A good question would be, what are the slowest moving objects? I'd think a black hole balanced between galaxies. The question makes my brain hurt.

what a crazy ass question. and i'm fried.

man...is there anything that actually stands still in the universe?i think stars rotate as well.

and you're right. there's a theory that says the universe is constantly expanding.i dunno. i would think the only thing that could stand still would be whatever is attached to the wall thats expanding?

This will open a can of existential worms for sure, but I'm going to give it my best shot, based upon what I know/have been taught/have been "conditioned to believe."

I agree with you. That is, if there's any validity to the 'Big Bang Theory." Not only is the universe expanding, it's expanding at an accelerating rate.

If we hold this to be true, then the most recent artifacts of the Bang would be the slowest-moving objects in the universe. IM (stupid, uneducated)O: A black hole stationed between two (or more) galaxies would still be part of the expansion, and would be still in motion at a speed relative to its nearest neighboring bodies.

We have a resident astrophysics expert among our ranks here at DT. I've learned a TON from his posts over the years, and hope like hell that he sees this thread... and jumps in with his observations. His stuff is fascinating.

I just wish I could remember which of us he is right now.

Swish may be fried on Girl Scout Cookies at present.... but I'm presently being slowed down by "Maker's 46"... and my "name recall" is a bit hampered, as a result.

Dawgs... who am I referencing? A li'l assist here plz....

in advance....

Clemmy

Good bourbon choice clem, I had a bit of Eagle Rare tonight

I'd argue there is nothing that 'doesn't' move. The slowest objects are the ones nearest the edge of the universe but even upon their creation they are carrying with them the momentum of the expansion. Just my 0.02c

I would guess that everything moves, because I believe that everything in the entire universe is connected in one way or another. The only difference is in degrees of separation.

The answer is 'no'. Everything is moving at some rate. If there was anything able to reach the temperature of absolute zero where all motion stopped, then you would have achieved this hypothetical state.

In laboratory settings, we have achieved states where the nuclear spin has been slowed which were 1/1,000,000,000th of a degree above 0°K, but have not reached it.

Clem - I believe you are thinking of Lyuokdea or however he spells it. Speaking of Lyuokdea, where has he been? I haven't seen him post in a long time.

Anarchy - Your comment raises the question of what is moving? I can be sitting on my sofa not moving but the inner particulate matter in me is moving. I think the initial proposed question was referring to moving from a location rather than moving in place.

If something was moving only in place then would that not be the center of the universe?

I guess we do have to define what is 'moving', but I think that in any case, if everything were to actually achieve absolute zero at the same time, then the universe would be in perfect stasis. Since that could never be achieved naturally, it is obviously hypertheoretical.

The answer is yes but only one thing is not moving. Everything else is relative to that. If you chose you can make another thing be the not moving thing and everything else is moving relative to it. The real answer is... it's relative. And no. Lol.

Hey, look, this video that came out a few weeks ago is mind blowing! The white dots.. stars. Nasa estimates something like a trillion stars (with a T, people) in Andromeda galaxy alone. Wowsers. (Click the Video to full screen!)

Nasa Releases Largest, Deep Field Photo Ever

That is just incredible, especially when there we consider that there are billions, or maybe even trillions, (or more!)of galaxies in the universe.

the absolute center of the Universe, that place from where the big bang originated would be the only place I could think of that would not be moving.

I'm feeling jipped now. I find out I'm moving at 98,000 mph, and my fitbit isn't increasing my calories, even a little.

Pretty cool video on how our solar system moves.
https://www.youtube.com/watch?v=0jHsq36_NTU

"It’s likely to make you feel like you are only a very, very small part of a universe"

Gee... Really? I thought I was a very, very, very small part of the Universe.(3 verys)

Thanks Einstein.

No I mean it. Thanks Einstein.

Hey I have a question.

The Earth revolves at 19 miles per second. How come we don't have to like hold on to trees or something?

I think the key insight, is that the speed something is moving (at a constant velocity) doesn't affect physics at all.

So, if I am on a rocket ship going 100,000 km/s away from the Earth, I can either say that I am moving quickly, or I can say that I am at rest, and the Earth is moving quickly away from me. There are no experiments which can tell me which of these is true (save one exception I'll discuss later) -- so for all practical experiments both rest frames are valid. This is the key concept of special relativity (for special relativity the key insight is that light moves at same speed in both your rocket's reference frame, and the reference frame of the Earth, and thus that can't be used to differentiate which frame is "right").

Note that none of the above is true for objects that are accelerating (the Earth is accelerating around the sun due to gravity from the sun), I am accelerating towards the Earth due to gravity from the Earth etc. That's the topic of general relativity and it's a different point entirely.

Another key concept is cosmic inflation. We've found that the universe is expanding, which means that any distant objects in the universe are moving away from each other. It turns out that the universe is expanding at a faster and faster rate (but that is not important for the rest of the talk). You can sort of think of this like a raisin bread. When you start cooking it, all of the raisins in the bread move away from each other while the bread rises -- but they are also not moving in their own frame (they are staying in the same position with regard to the bread around them. It is the bread itself (space in this analogy) that is expanding. Again each raisin can argue that it is standing still, and everything else is moving away.

There is one reference frame that is unique (though physics in this frame is exactly the same as every other frame). There is a cosmic microwave background which was emitted from the early universe. Specifically, the early universe was very hot, and the gas floated around like a plasma (like in the plasma globes you've seen. That is opaque to light, which means that light in the early universe couldn't travel freely without being absorbed and re-emitted constantly by the universe plasma. Finally the universe cools down into molecules (bound protons and electrons) and these don't absorb light efficiently. Light emitted after this time can travel freely all the way from the Early universe to us, without being disturbed. This CMB light is observed everywhere in space with nearly the exact same features (same intensity and energy in every direction).

Except, our galaxy is moving at some random velocity with regard to this CMB light. It means that we are moving into the photons on one side of the universe, and away from the others. This makes photons from the universe we are moving towards look like they have a slightly higher energy than photons from behind. It turns out that our solar system is presently moving at 369 km/s compared to the frame where the CMB would be fixed in every direction. You could easily imagine some star that is moving at that speed. Physics would be the exact same, but it is (I guess) a unique reference frame to be in.

Chewing gum on the sidewalk?

Two different forces here, and two different reasons why you don't notice them.

The first is the rotation of the Earth - this can look like an acceleration on our bodies, and could theoretically throw you of of the Earth. Note that the gravitational pull from the Earth can accelerate us towards the ground at 9.8 m/s^2.

Though the Earth is rotating (and that will accelerate us away from the Earth), it is much less. The acceleration from the Earth's rotation is a = v^2 / r, and the rotational speed of the Earth is 465 m/s, and the radius of the Earth is 6,378,100 meters. So the "acceleration"* you feel from the Earth's rotation is 0.034 m/s^2, much smaller than the gravitational force of the Earth, and you are pinned down to it. Note, that this effect is measurable though. The effective gravitational constant near the Earth's equator is measurably smaller than near the Earth's poles (due to the rotation of the Earth).

The other force is the Earth being pulled around the sun, at around 30 km/s. You can calculate the acceleration from this ( (30 km/s)^2 / 150,000,000 km) and it's 0.006 m/s^2. So it's very very small (much smaller than the Earth's gravity). More importantly though, you are being pulled around the sun at the exact same acceleration (since you are also moving around the Sun's mass) so you won't even feel that very tiny force.


* I put acceleration in quotes there because it's not a real acceleration (you just want to move straight and in the curved reference frame of the Earth's rotation, straight is away from the surface of the Earth, it's a technical point).

I enjoy reading people who know more [in this case---WAY MORE] than I do. Some people get offended by things like that. I don't. I'm appreciative that you are willing to share what you know.

I am not smart enough to understand it all, but thanks man.

That's all well and good, Lyuokdea, but would you go post something about the Browns?

The clock toward the end of the workday.

I do have a question that I tried to see if it was already answered. I saw that gravity is is not as heavy at the equator, but do the people there travel faster than those of us away from the equator, like the "Crack the Whip" game we played years ago?

It seems it should be the same but it also seems the equator is traveling a further distance.

I think the lower gravity has to do with the equatorial bulge. Because people and other things are further away from the center of the earth, they experience less gravity (not enough to notice, but it is calculable).

And yes, they do travel faster because of the spin of the earth. Someone standing 10 feet away from the north pole is still spinning, but they’re covering a lot less distance in the same time. They’re still rotating once every 24 hours, but not as fast as the person standing on the equator, who has to travel all the way around the earth in the same 24 hours.

This is where I’d need Lyuokdea’s help. The person standing on the equator is experiencing less gravity and more speed, those two variables are causing them to experience time faster than someone in Cleveland or on the North Pole. I think it’s something built into the special theory of relativity. All acceleration is at the speed of light, but it’s a combination of speed and time (I think of it like a gas pedal and clutch, they’re always sliding in opposite directions). A photon is moving at the speed of light and zero of its time is moving through time. So, to a photon, no time passes between its birth and death, no matter how far it travels. To a person on the equator, they’re moving faster than us, so less of their acceleration is through time. I know gravity also has an effect, but that’s a whole other theory too (general). I’m starting to confuse myself.

Speaking of the earth’s spin, watch this cool video if the earth suddenly stopped spinning.

That's basically correct - though the two different factors actually move in different ways. In the case that objects are moving at a constant speed physics is invariant, both people think the other person's clock is moving slower (and both are equally right). How can both clocks be moving slower (well in order to check you'd have to have one of them go back and catch up with the other one, he'd have to accelerate to do that, and so he wouldn't be in a constant velocity frame anymore, so he'd be the one that is wrong).

At the equator you are accelerating at a faster speed to go around the Earth (because you have to go farther in the same 24 hours -- acceleration is v^2 / r = omega * r (where omega is the angular velocity around the Earth, which is 1 revolution/24 hours for both observers -- and r is bigger at the equator). From this his clock moves slower than the person who is at the North Pole.

However, the other affect is that his acceleration due to the gravitation force of the Earth is smaller (it is the same mass and he is farther away). Gravity and acceleration are the same (that is the theory of general relativity -- as an experiment think of being inside an elevator that starts going up very quickly -- and is in space. At first you are weightless, but as it starts accelerating faster and faster, you start feeling pushed by the bottom of the elevator. When it gets to 9.8 m/s^2 (the gravitational acceleration of the Earth), you wouldn't be able to tell if the elevator was still accelerating, or if it were just sitting still on the Earth.

It turns out the second effect makes time go faster for people who are higher up - and that it is more important than the increased acceleration from the revolution of the Earth, so time actually moves a little faster for people at the equator than at the poles (we're talking about a billionth of a second per year).

Interestingly, this does have to be taken into account for GPS systems. The satellites in GPS basically just send out a signal which tells you what time it was (to the percise nanosecond) when they sent out the signal. And since you know where all the GPS satellites are, and how fast the speed of light is, you can patch together the information from a bunch of satellites to get a position.

However, the clocks on board the satellites are moving faster than the clocks on Earth, by nearly 38 microseconds a day. Light moves 300,000 km/s, which means your position would be wrong by 11 km for every day the relativity effect isn't taken into account. GPS would have been rendered entirely useless within minutes if general relativity wasn't taken into account!

WOW!

I'm impressed. I would actually prefer to read your posts than watch tv.

Thanks! I appreciate it....

Though I'm not sure your reaction would be the same if I'd spent the last dozen years studying climate science...

Lyuokdea is so knowledgeable I procrastinate my physics homework with his posts on physics.

It would be a pleasure if you had because I appreciate someone who really knows the score. So much Politics and division surrounds climate science that a guy like me can't figure what is right and what is bull, what is important and who is just trying to make a buck.

I'm going to stop posting about climate change after this, because I'm hijacking the thread (and I know I started it by taking a potshot)....

But I don't really understand what's different about what I've said on this message board, and what the IPCC 2014 report said about Climate Change. I'm an expert on astrophysics (not bragging here, but I've worked on it for a long time), and they are experts on Climate Change (and a lot of them are much much smarter than I).

Modulo what different political parties want you to believe (and the fact that there is money involved in Climate Change decisions, and not much money in astrophysics) -- there's no reason to accept what I've written above, but doubt IPCC 2014 (or the United States National Research Council, American Physical Society, American Chemical Society, NASA, or the Department of Defense*).

In general science is about determining what the evidence supports. What hypotheses can be ruled out, and which continue to be viable. It's hard for me to imagine people being interested in the output of science in one area -- but then ignore it when the truths become uncomfortable**.


* The Department of Defense is always an interested example - since many people on here argue that "well, scientists talk about global warming so they'll get grant money". The DoD has nothing to gain (in terms of grants) by talking about climate change. DoD scientists don't get grant money for working on specific projects - and the military has every reason to continue to pollute with large warships etc. But the Pentagon report unambiguously calls climate change one of the biggest future security risks (http://www.nytimes.com/2014/10/14/us/pen...ity-threat.html)

** This last statement is not climate change (or conservative) specific. Don't get me started on liberal anti-vaxxers, anti-GMO, or anti-gluten advocates.

Inertia. The earth is moving that fast, and so are you. If the earth suddenly stopped rotating, we'd all get to experience what a 1000 MPH crash feels like.

As for something not moving in the universe, I have to agree with an earlier post. If the universe was created by the big bang, the only thing that couldn't be moving would have to be at the exact center of that explosion. That is also assuming the explosion was completely symmetrical. For something else to not be moving, it would have had to come into contact with an object of the same mass moving back into the center at the exact same velocity and exact opposite direction. As there was supposedly only one big bang, there would be no such object traveling back to the center.

That's pretty close, except there really is no center of the big bang. It's like the raisin bread I mentioned earlier. As you cook the bread it expands and all the raisins in the bread get farther from each other.

Now, pretend that you can "uncook the bread" back until the dough gets smaller and smaller and smaller - until it's an infintesimal size (with all of the very tiny raisins stuffed at the same point in the middle). That's the universe at the moment of the big bang -- infinitely small and infinitely dense (or at least -- a good approximation of that for as far back as our models can predict).

Now, start cooking the bread and everything expands into its current position -- note that every raisin can equally proclaim that it was at the center of the big bang - and that it hasn't moved since (it started right there in the center, and it's just been sitting here baking ever since) -- according to that talking raisin -- it's everything else in the universe that has moved away from it!

So, we are at the center of the big bang - just as much any other galaxies are. The Milky Way has some velocities that get picked up by other effects (mostly our gravitational interaction with the Andromeda galaxy -- but also previous interactions with other galaxies early in the Universe's history) - so from the CMB argument above we can't quite argue that we are sitting still compared to this explosion. But we can argue that we are pretty much in the center of it all.

EDIT: I should add, that a central point in this argument, is that the raisin we are living in (our galaxy?) shouldn't be able to see the edge of the raisin bread. As far as we know that is the case - our view of the universe is limited by the fact that the universe isn't infinitely old (13.7 billion years), and that the speed of light is constant -- that means we can only see things that are so far away. When we look out in space, the universe looks the same in every direction (same number of distant stars and galaxies) -- we can't see an edge in any direction we look.

As far as we know, the raisin bread that we are living in continues to expand far beyond the maximum distance we can see (and possibly forever) -- thus we are not sensitive to any edge of the universe.

So, we can legitimately claim to be the center of the universe and everything revolves (or moves) around us. Got it.

Of course there is no center once you start throwing infinites about. Infinitely small or infinitely large are impossible to grasp, calculate, or prove. We are the atomic particles of another universe just as another universe is the atomic particles of ours. Quantum theorizing should only be done when one is particularly high. Pun intended.

Ultimately doesn't there have to be a center of everything?

If speaking of somethng linear, the center can not be obtained if the universe is expanding as it would always change, but since all thngs in nature are circular then there must be a center, no?

Of course Zeno proved all motion did not exist anyway except as an illusion. so this is all moot

What's the center of the number line?

You might say it's 0, because there are the same number of things on one side as there are on the other -- but there are also the same number of things on each side of the number 1, or -5 for example.

That is, for each number that is on the right of -5 (say -3, for example) there is also a number that is on the left (say -7), and I can match these to each other one-to-one (which is a technical way of saying, I can make a match such that there is exactly 1 number on the left that accounts for any number on the right and vice versa).

Hint: There are types of infinities that you can't do this for -- for instance, you can't make a list of integers that accounts for every real number (rational and irrational).

A fact that will mess with your brain though - is that you CAN make this one to one correspondence between the integers and every set of rational numbers (fractions) in existence. That is, you can come up with a relation so that every fraction you can write down is related to exactly one integer, with no overlaps.

Quiz time!

Lets say I am driving a school bus with 17 students on board.
At the first stop, 8 students get on while 3 get off. Next stop,
15 students get off while 9 get on. Later 13 students get on while 5 get off.

What color are the bus drivers eyes?

Red.

I think the riddle is supposed to start "you are a bus driver"

Did you question the question instead of answering in school?

-FAILED

Feeling smart now, back to Gilligan.

Father Sun...

http://www.liveleak.com/view?i=f44_1423684630

My 18 year old son when there is work to be done.