Is the Universe Expanding?

If the universe is expanding how did the space shuttle launched from earth reach saturn to take photos. The velocity of the spacecraft towards Saturn is negligible compared to the velocity at which Saturn is moving away from the spacecraft.

The background radiation from the big bang seems to have no effect on the spacecraft's overall functioning. why?

If the universe is expanding how did the space shuttle launched from earth reach saturn to take photos.

The tiny (in galactic trems) distance to Saturn means that the effect of the expansion relative to us is tiny.

The background radiation from the big bang seems to have no effect on the spacecraft's overall functioning. why?

Just like on Earth, it's a measurably tiny amount of background noise that can easily be filtered out.



[edit on 31-7-2004 by Zzub]

Originally posted by websurfer
If the universe is expanding how did the space shuttle launched from earth reach saturn to take photos.

The universe is expanding in the sense that the galaxies are moving away from each other, since they were accelerated by the big bang. I don't think the distances between stars or between a star and a planet or between a planet and a planet is increasing. All the planets are gravitationally bound to the Sun (and to each other), and all the stars including the Sun are gravitationally bound to the center (black hole) of our galaxy, milky way.

Its like when you heat a metal, and as it expands the distance between the atoms increases, the radius between the nucleus of the atom and electrons does not increase, nor does the distance between electron orbitals.

The velocity of the spacecraft towards Saturn is negligible compared to the velocity at which Saturn is moving away from the spacecraft.

Saturn is not moving away, it is orbiting around the sun though!

Thanks for the help guys I really wanted to clear that up.

The Space Shuttle only obits our planet earth.

An entirely different space craft named Cassini went to Saturn.

Here you can take a look at Cassini.

Cassini

Here you can see the space shuttle.

Space Shuttle Discovery

Pioneer 11 then Voyager 1 and 2 were the first space probes to visit Saturn

Voyager


Pioneer 11


Good Luck

X





[edit on 2-8-2004 by Xeven]

The realy interesting thing is that for all the galaxies to be moving away from each other , space itself has to be expanding . I think of it in the terms of a balloon with two floating points inside . When you blow more air into the balloon , the two hovering points increase in distance from each other , as do all oher points inside the balloon

This is the only way everything can be moving away from everything else without a central point of origin being defined IMO .

This has always puzzled me , I understand that particles can blink in and out of existence , but where does the exess "space" come from ?

This sounds like a question for Quest , pardon me if I add to your question .

The energy of the universe is dominated by empty space emitting a repulsive form of gravity that is pushing the universe apart.this force is a property of the vacuum of space itself, an energy that acts on a large scale to stretch space and thus counteract gravity's restraining power.

This means that most of the universe is influenced by an abundance of some weird form of energy whose force is repulsive."

If the universe is expanding, what would slow it down? Hawkings seems to predict a big crunch following the big bang but space is frictionless.

The big crunch
I'm looking at it like this: Throwing a stone in the air, speed decreases to zero(stops), and falls back down to ground.

i find the whole idea of an expanding universe puzzling to me. if its infinite it has no border, hence no TRUE expansion, the expansion we are observing could be little more than a fraction of it expanding while another part is collapsing, sort of an ebb and flow.

but for the universe to expand it has to have a border otherwise if it is trully infinite then it is not expanding, merely moving around.

i hope that makes sense to someone else!

Originally posted by websurfer
If the universe is expanding, what would slow it down? Hawkings seems to predict a big crunch following the big bang but space is frictionless.

The big crunch
I'm looking at it like this: Throwing a stone in the air, speed decreases to zero(stops), and falls back down to ground.

It is like Escape velocity, if the energy of Big Bang was strong enough to escape the gravitational pull of ???, then we would expand forever, if not we would fall back into ourself. I am not sure what ??? means?

Throwing a stone in the air, speed decreases to zero(stops), and falls back down to ground.
Throwing a stone into the air and it falling back to Earth is the result of the slowing down of the stone due to the friction of air and gravity combined. The stone never comes to a complete stop unless it's thrown perfectly vertical.

Originally posted by websurfer
If the universe is expanding, what would slow it down? Hawkings seems to predict a big crunch following the big bang but space is frictionless.

The big crunch
I'm looking at it like this: Throwing a stone in the air, speed decreases to zero(stops), and falls back down to ground.

The density of the universe determines its fate and its geometry.
If the density of the universe exceeds the critical density, the geometry of the universe is closed, positively curved like a sphere. In that case, there is enough mass/gravity to overcome the expansion, and a big crunch takes place.
If the density of the universe is less than the critical density, the geometry of the universe is open, negatively curved. In that case, there is not enough mass to overcome the expansion, thus the universe expands forever.
If the densiity of the universe is equal to the critical density, the geometry of the universe is flat, like a sheet of paper. In that case, the universe will also expand forever, however the expansion will gradually slow down, but will not end.

According to the latest measurements of WMAP(WILKINSON MICROWAVE ANISOTROPY PROBE), the universe is flat. So no big crunch!

From map.gsfc.nasa.gov...
"The matter of which we are made is only a small portion of the Universe, 4%. 23% is an exotic type of material known as "cold dark matter". And 73% is an even more exotic "dark energy". One possibility for the dark energy was introduced by Albert Einstein, a so called "cosmological constant...The geometry of the Universe is flat."

[edit on 18-8-2004 by jp1111]

Originally posted by jp1111
According to the latest measurements of WMAP(WILKINSON MICROWAVE ANISOTROPY PROBE), the universe is flat. So no big crunch!

Whew!

[edit on 04/8/18 by GradyPhilpott]

Originally posted by jp1111
According to the latest measurements of WMAP(WILKINSON MICROWAVE ANISOTROPY PROBE), the universe is flat. So no big crunch!

Wait a minute I thought it was impossible to find the density of the universe, I read it somewhere.

Originally posted by ThePrankMonkey
i find the whole idea of an expanding universe puzzling to me. if its infinite it has no border, hence no TRUE expansion, the expansion we are observing could be little more than a fraction of it expanding while another part is collapsing, sort of an ebb and flow.

but for the universe to expand it has to have a border otherwise if it is trully infinite then it is not expanding, merely moving around.

i hope that makes sense to someone else!

Its almost as if u were to imagine Eienstien's theory of relativity, where objects sit ontop of a "stretched out sheet" and the more mass the bigger the indent. So we can imagine "our" universe as an indent of a bigger and "infinite" sheet that we are expanding on.

Originally posted by surfup

Originally posted by jp1111
According to the latest measurements of WMAP(WILKINSON MICROWAVE ANISOTROPY PROBE), the universe is flat. So no big crunch!

Wait a minute I thought it was impossible to find the density of the universe, I read it somewhere.

The density can be calculated using the hubble's constant. I'm no physicist, so I won't try to explain how, but here is a link: hypertextbook.com... (scroll down to "cosmic expansion").
How is hubble's constant measured? There are several methods as explained here: www.upei.ca...
and www.phys.unsw.edu.au...

Originally posted by websurfer
If the universe is expanding how did the space shuttle launched from earth reach saturn to take photos. The velocity of the spacecraft towards Saturn is negligible compared to the velocity at which Saturn is moving away from the spacecraft.

The spacecraft is part of the universe no?

The background radiation from the big bang seems to have no effect on the spacecraft's overall functioning. why?

Please explain why it should.

IF hmmmm

If the universe is indeed expanding as some claim, and as some experts believe is the result of a big bang where all that is known to exist in this supermassive universe, was once compressed into a point in space smaller than a single atom, and as some of these same experts believe the expanding universe will one day slow to stop then contract back to that single point in space, then BOOM it all happens again, have we been here before, maybe an infinite number of times??

Gazz

if the universe is expanding, and all the galaxies are set in motion because of the big bang, why are there galaxies colliding into eachother? wouldnt they all be going in the same direction if they all came from the same point?

Originally posted by WolfofWar
if the universe is expanding, and all the galaxies are set in motion because of the big bang, why are there galaxies colliding into eachother? wouldnt they all be going in the same direction if they all came from the same point?

The expansion of the universe is trying to set the galaxies apart and the gravity between the galaxies is trying to pull them together. So if two galaxies started out very closely, gravity wins and they collide!