The galactic plane

[ajetrumpet]

If you're in a dark place on a clear night, it's that time of year where you can look strait up and see the ring of dust in the galactic plane of the milky way. Man, that's awesome stuff! Saw it for the first time tonight!

 

[Galaxiom]

I am fortunate to live in a rural area in Australia so the sky on a clear night is absolutely awesome. Down under we can also see the Large and Small Magellanic Clouds which are two minor galaxies in our cluster at about 160,000 to 200,000 light years away.

The sheer immensity of the Milky Way with a diameter of 100,000 light years and something like 300 billion stars blows me away. Nice that we live in such an excellent example of a giant barred spiral galaxy.

Have you visited the Galaxy Zoo project?
http://www.galaxyzoo.org/

That is actually where I got my username when I contibuted to their first classification project.

Take a look some of the photos in these threads.
http://www.galaxyzooforum.org/index.php?board=4.0

They take a while to load but are well worth it. Absolutely stunning beauty.

 

[Galaxiom]

Adam. Take another look. What looks like dust is actually light from stars in the Milky Way that are too far away to be individually resolved by the naked eye.

Basically only about 9,000 stars in the whole sky can be individually resolved without magnification and all those lie within a distance of just over 4,000 lightyears. Even at this distance we can only just see Hipparcos in the constellation Cassiopeia because it is a super giant 100,000 times more luminous than the Sun.

(Note: I have ignored anomalies such as GRB 080319B which was theoreticaly briefly visible to the naked eye from a distance of over seven billion light years. http://en.wikipedia.org/wiki/GRB_080319B)

 

[ajetrumpet]

are you sure that's what it is? I don't know man...

did you study astronomy in the past? I love looking at the pictures and expanding the mind to the impossible possibilities, but I almost failed all the courses i took in astronomy. the physics I just had absolutely no interest in...

luminosity? AU? megaparsecs? ummm..no thanks!

now stuff like multiple universes, black holes, event horizons, near earth object collisions and red giants. that's awesome stuff!

 

[Kryst51]

are you sure that's what it is? I don't know man...

did you study astronomy in the past? I love looking at the pictures and expanding the mind to the impossible possibilities, but I almost failed all the courses i took in astronomy. the physics I just had absolutely no interest in...

luminosity? AU? megaparsecs? ummm..no thanks!

now stuff like multiple universes, black holes, event horizons, near earth object collisions and red giants. that's awesome stuff!

Sounds like you enjoy SG-1

 

[ajetrumpet]

Sounds like you enjoy SG-1

i've never seen that show actually. i stopped watching dean anderson after macguyver was canned.

 

[Lightwave]

A few more things you might find interesting

Roughly 1/3 of the stars you see in the sky are binary that is they have a companion star or stars that they rotate around.

There are approximately 88 major constellations - varies from culture to culture.

Nearly everything visible by the naked eye comes solely from objects in the milky way

The stellar disk of the Milky Way galaxy is approximately 100,000 light years in diameter, and is believed to be, on average, about 1,000 light years thick. It is estimated to contain at least 200 billion stars and possibly up to 400 billion stars.

The next nearest galaxies are, estimated to be 120 million light years away

The herschels brother and sister tried to figure out where the solar system was in the galaxy by pointing their telescope in one direction and counting the stars and then pointing it in the opposite direction and counting the stars. They had this theory that they were in a disk and that if they were there would be more stars visible in the direction that looked into the hub. Sound reasoning unfortunately because there were so many stars they got so many in both direction they couldn't draw a theoretical conclusion from their work. (which subsequently did help establish our position). Wherever they pointed their telescope they saw millions of stars.

If you are really interested in all of this stuff I recommend a couple of lecture courses by a Professor Richard Pogge from Ohio State University. A couple of years back he produced two podcasts Astronomy 161 and Astronomy 162. The first deals with the solar system the second with the galaxy and the universe. Can't recommend them high enough. Will search for a web link.

 

[Lightwave]

For anyone downloading the podcasts I think it would be a nice gesture to make a contribution to the Ohio State. They are very high quality.

Astronomy 161 podcasts

http://www.astronomy.ohio-state.edu/~pogge/Ast161/Audio/

Astronomy 162 podcasts

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Audio/

 

[Galaxiom]

I'm not an astronomy expert by any means but always been interested particularly since living for the past 30 years with such a good view of the sky.

I am more fascinated by the physics and the mind boggling statistics. Few things moved me to the extent of classifying galaxy after galaxy for hours at the Zoo. Each one with tens or hundreds of billions of stars, click after click after click yet I only saw a tiny fraction of the collection which in itself is far from the whole sky.

Or an object that could be seen with the naked eye at a distance of
40,000,000,000,000,000,000,000 miles. How bright must that be?

Or our own sun losing 4 million tonnes every second in energy alone without considering the particles in the solar wind. And still doing it after nearly five billion years.

We are so lucky to live in a time where we can know the truth of the amazing universe we live in and find it is far more awe inspiring than any myth our ancestors had to settle for.

 

[Lightwave]

From what I can tell the history of Astronomy is the history of Physics.

Many of the developments of Physics came about in order to explain Astronomy.

There's a lot of crazy stuff going on out there.

massive speeds - light bending - time standing still - explosions and lets not forget

......single point infinite masses

 

[Galaxiom]

The Universe is certainly the ultimate laboratory of reality. Despite its size the LHC is puny in comparison.

Those who thought it was going to make black holes that would consume us all were severley deluded. It is sad that so much effort had to be expended to dampen their paranoia.

 

[Galaxiom]

This is my favourite LHC statistic.

The total energy carried by the two beams is equivalent to the kinetic energy of a TGV (French high-speed train) running at 222 km/h (139 mph).

Under nominal operating conditions the beam pipes contain one nanogram (1.0×10-9 grams) of hydrogen, which, at standard temperature and pressure, would fill the volume of one grain of fine sand.

Nothing else packs so much energy into so little.

 

[ajetrumpet]

......single point infinite masses

gotta love the black holes!

I have a ? for you guys...scientists still think the U is relatively flat. HOW flat is flat though!? If flat is a sheet of paper, then they're wrong. I guess I have never read if the hubble has been able to see outside the galaxy far off the galactic plane. Has it? I would assume not, since it's orbit never changes vertical position. For example, if outside galaxy object images could be captur ed from a sattelite at the north pole AND at the south pole, obviously the U can't possible be flat. This range covers all directions! Has there been such observations?

If the hubble is simply looking in all directions throughout it's orbit near the galactic plane, that doesn't really tell us anything either, because the plane has absolutely nothing to do with the flatness of the universe. the galactic plane could be at 90 degrees of the U's plane, and how would we know the difference? Take this picture for example:

imagine the big galaxy is ours. and imagine the hubble taking pictures on the galactic plane. if it captures a deep field image, then those object that it's looking at are obviously telling us that the universe cannot be flat. Does this make sense to anyone?

 

[Lightwave]

I think the conclusion that the astronomical community draws from pictures such as that is there are other galaxies much like our own which appear to have similar characteristics to our own.

This they call the Cosmological Principle - the idea that our part of the Universe ain't that special. Thus we are probably not in the centre or at the edge or anywhere particularly special at all.

There is a lot of debate about what the shape of the Universe is but that tends to be in terms of what shape of all dimensions are more as a mathmatical analogical transformation from multiple dimensions down into three dimensions rather than a real thing that we could ever experience. Einstein's conjecture(which is the best we have at the moment for large objects) managed to predict and explain certain observable features that suggest that space and time are inseparable such that each dimension relies on each other for its existence. Thus

A O point can be stretched into a 1 dimensional point.
A 1 dimensional point can be flattened into a 2 dimensional space
and you can bend 2 dimensions round on itself into a 3 dimensional object.
After that we can only observe direction 3 dimensions which makes further dimensions difficult to comprehend. In fact human science uses such reduced transformations frequently. A classic brain scan is just a cross section through the brain at a particular level. As the scan goes up or down through the brain the cross section changes markedly. An individual scan would all a 2 dimensional being would ever be able to experience of a 3 dimensional brain. So the actual shape may vary greatly on how the shadow / cross section is taken. Just thinking about it you could take a cross section of a cube that in 2d would give you a square, rectangle or triangle and I think you might be able to get something like a hexagon (just figuring it out in my head!) and probably others as well.

Ignoring time for the second(joke) they think that the three dimensions we experience may be bent round on themselves so that if you go for long enough in one direction you end up right back where you started again. Not only that they think space time might be expanding. All their data seems to indicate that everything is going away from us. The cosmological principle requires us to assume that we are in a location that is not special. So the assumption is that everything is not accelerating away from us everything is accelerating for everything else. How is that possible? Well in the same way that if you are a point on a baloon's surface which is being blown up. You as a point will get further away from all other points on the surface despite the fact that no point is actually moving. The space time is actually expanding.

This means that given enough space even light won't be able to travel all the way across the universe ever. The distance of the universe will expand at a speed greater than disance that is being "created".

What this means from our perspective regards - the universe doesn't have a shape as we would call it, it is infinite in every direction and both in time to the future and time to the past

Lots of shapes have been expressed as analogies for the shape of the universe but these are analogies of multi-dimensions take your pick
Saddle
Do Nut
Hot dog
As explained if that's not bad enough you have to live with the idea that all of above could be correct because all are just shadows of the real thing that has lost information in the reduction of dimensions down to our understanding.

No ones come up with the Maths or an experiment that can explain it. The closest thing that they've come up with is General relativity and the Big Bang Theory and the background radiation scan that seems to say exactly what the Cosmological Principle had predicted. Everything is pretty much the same in every direction.

I know people have figured out what a shadows of 4 dimensional objects could look like in 3 dimensions. Maybe all 3 dimensional objects are actually shadows of multiple dimensional objects. In fact if everything has the same number of dimensions and that is greater than we can observe stands to reason that that's the case? (Maybe)

I suspect that Unified theory or the LHC offer the best steps forward at the moment into figuring out just what is going on.

When your into String Theory , General Relativity and Quantum Mechanics your into heavy heavy mathematics and there are only a few people who understand this.
The vast majority of stuff out there is good natured unprovable conjecture.

There's a famous quote from a Physicist I think it might have been Neil Bhors who was asked about Quantum Mechanics and how many people understood it… (Please note later corrected by LPurvis relates to Arthur Eddington and General relativity and not Neil Bhors and QM)

He said himself and then there was a pause

To which the journalist aksed "Why the pause?"

Bhors goes

"I'm trying to think of anyone else who understands it"

But just because a lot of people say it doesn't mean that its true

As Galileo is rumoured to have said while signing the Catholic disclaimer of a heliocentric solar system

Epur si mouve

(and still they move)
(apologies for dodgy Italian!)

 

[ajetrumpet]

oooooooook. some of that huge post just didn't make sense. wow. i think i can just leave it at the fact that there really is no directions in the universe. i'm happy with that!

 

[Galaxiom]

Great photo Adam.

Look at all those galaxies. Every light except the red star below the big one is a galaxy. We are seeing the light of many trillions of stars yet the field of view in this photo would be tiny.

There are more stars in the Universe than grains of sand on all the beaches on Earth.

 

[The_Doc_Man]

Visit the Hubble site and browse. Some of the Deep Field and New Deep Field photos are just mind-bending, but they have others that show hourglass shapes that they think might be the event horizon of one of Stephen Hawking's "spinning, charged" black holes. That one blows me away every time I look at it. I'll see if I can find the link another time. But just browse that site. HST, by the way, has looked above and below the plane of the Earth's orbit as well as almost straight out. Everywhere they've looked, they've found stars. ALL directions. In fact, in line with the "what is the shape of the universe" question, Hubble was trained on an area they thought MIGHT be devoid of any stars at all, because they were looking for the "edge" of the universe. Instead, they found the images now referred to as the "Deep Field" images.

As to how it is possible that EVERYTHING is moving away from us... that's easy.

Imagine your matter is part of the super-singularity that preceded the Big Bang. Now ... tick tick tick... BANG. Stuff gets ejected in every direction from the center of the bang. But why would you assume it is ejected at uniform speeds? In ordinary explosions, that is not the case. The mass of the ejectae become relevant to their speed.

So some stuff is moving faster. Some stuff is moving slower. Assume we are more or less in the middle of that range. OK, there are three places to consider. Farther out than us from the epicenter of the bang, stuff must be moving faster. OK, we'll see that as that they are moving away from us. Closer in than us from the epicenter of the bang, stuff must be moving slower. To them, WE are moving away, and everything is relative. So to us, it looks like THEY are moving away, but in fact it is us moving faster than they are.

Now, the third category - stuff that should be moving at about our speed. But let's think about an imaginary spherical surface of all star-stuff moving at the same speed from the epicenter. But as the radius of that sphere expands, its surface area expands. If we maintain the same "latitude" and "longitude" on that sphere (i.e. no sideways drift) then as the radius increases, the distance between two points that are keeping their LAT/LON the same will have to increase with a speed of the square of the change in radius. So again, our neighbers seem to be receding from us (and we from them.)

Now, if we just just pinpoint the epicenter, we could build the final model of the ejectae and figure out where we REALLY are in the universe. But I think we don't quite have the observational tools yet to get that exactly right. It would require a LOT of mathematical regression analysis given the number of telescopically observable stars.

BTW, if you want clear views at night, rural Alabama, the outskirts of Ft. Stockton Texas, and the west coast of Maui were all excellent viewing spots when I visited those places. I had my telescope with me in north-central Alabama and in Texas, but Hurricane Katrina took my scope from me. These days, my cataract-laden eyes can make out the moon and some stars but not like when I was a kid. Can't wait for the eye surgeon to schedule the cataract surgery so I can see again! But that's OK, the stars will wait.

 

[Lightwave]

...... because they were looking for the "edge" of the universe. Instead, they found the images now referred to as the "Deep Field" images.

That was not quite my interpretation of the theory. Your explanation suggests a universe solely based on classical mechanics with the big bang being a classical explosion as per dynamite etc... ie the bang occuring in a massive "space" and expanding outwards after that.

My understanding of the theory is that the big bang was the creation of the the dimensions themselves and the universe isn't expanding into a blank area. The universe was created all together infinite in every direction although possibly bent round on itself. Thus like a game of asteroids the ship can travel forever in one direction although repeatedly ending up at the same location ( for anyone that doesn't know asteroids was a uk arcade game whereby the player was a triangle in the middle of a set of asteroids which drifted off screen only to appear at the opposite side) . This is analogous to a 2 dimensional creature living in a universe that is essentially the surface of a sphere.

When looking into the dark areas of the universe we are not looking towards the edge of the universe rather we are looking to the beginning of time because the distances are so big we will never be able to get a current view of the universe.

The expansion comes from the fact that the space time continuum is expanding itself much like pumping up a baloon with us living on the surface as per your lat long example on the surface of a sphere. Thus in the asteroids game the resolution of the screen is gradually increasing. If we were in the game we would be aware that it would take longer to travel from one repeating point to the same repeating point.

Thus even measuring all of the different trajectories of all the different bodies and tracking them back would not give a starting explosion point and why the background radiation of the universe is remarkably constant (only marginal gradients between everything). In fact this low level constant hum was seen as justification of the big bang showing that it happened everywhere.

Everywhere is both at the centre and at the edge of the universe!!!

Every podcast and lecture I have listened to seems to state as fact all the different stages of the first instances of the Big Bang with incredible detail in terms of time. Really don't know what they are using to do this but there seems to be a lot of consensus. Maybe they are using Quantum Field Theory which along with Classical Mechanics, Quantum Mechanics and General Relativity seems to be used depending on frame of reference of objects (relative speed they are travelling) and the size they are.

It is considered that the end of the universe may be either

...a cold death where the space time continuum gets so large that everything drifts off so far apart that there is just masses and masses of vacuum.

....A big crunch whereby the universe contracts and maybe there is another big explosion.

(this next bit is my thoughts)
Of course there may be something whereby everything drifts off apart from each other for a bit and then some factor reverses it all and space time deflates so everything flows back into a big bank mark 2. That conjecture would allow for expansion contraction big bang expansion contraction big bang ad infinituum which seems quite appealing in a symmetrical sort of way. (to me anyway)

The funniest thing with this is that it still doesn't get any closer to the ultimate question

Where did it all start!!

 

[mcclunyboy]

My top 5 astronomical observations -

1- Saturn - ITS AMAZING through a scope or binoculars + you can see moons of course
2- Milky Way at a dark spot
3- Space Station when it is visible
4- Moon through binoculars, or telescope, the detail is unbelievable
5- The Orion Nebula...

You can see all the above with your naked eye, but the better your magnification the better the viewing...

Quicquid Nitet Notandum

 

[The_Doc_Man]

Lightwave, as long as we aren't the planetary system on the leading edge of the expanding "front" (whatever it is), and as long as enough time has passed, what I described in classical mechanics might be true - now. I won't go so far as to say it was always this way, but we are no longer in initial conditions.

Further, you have two other comments that need reconsideration (perhaps). First, in M-theory, we don't have to assume that the big bang was the start of everything. It was just a massive disruption of our little corner of the universe.

Second, we don't have to assume that there WAS a start. This is a philosophical thing that is hard for people to accept - yet theists accept an eternal God. Why do you not want to accept an eternal universe?