Cosmology question, the metric expansion of space

I'm grappling with a cosmology question, and my internet research and
questioning has so far been in vain.


Briefly: Is the ongoing expansion of the universe exclusively
spatial, or is time also expanding?


If so, what are the observable results? If not, what causes time in
this case to be influenced differently than the spatial dimensions?
If the question is bogus, what are my faulty premises?


Any answers, direction, or resources would be appreciated.


Conrad.

Dear Conrad:

On May 26, 11:12*am, Conrad wrote:
I'm grappling with a cosmology question, and my
internet research and questioning has so far been
in vain.

Briefly: *Is the ongoing expansion of the universe
exclusively spatial, or is time also expanding?

For the sake of completeness, let's express "expanding time" as clocks
getting faster and faster as compared to some duration in the distant
past (say the emitted frequencies of emitted CMBR photons).

When we express expansion, we linearize time (because we have no real
reason not to do so) which shows an expanding Universe (and linear
time of course). We'd always measure time intervals to be
unsurprising locally.

If we recognize that expansion correlates with "relaxing global
curvature of spacetime", then yes local clocks do "run faster
everywhere" *and* there is still some expansion of space to achieve
the total effect.

If so, what are the observable results?

Same. One is just a whole hell of a lot harder to talk about.

*If not, what causes time in this case to be
influenced differently than the spatial dimensions?
If the question is bogus, what are my faulty
premises?

Any answers, direction, or resources would be
appreciated.

http://www.astro.ucla.edu/~wright/cosmology_faq.html#UN
http://www.astro.ucla.edu/~wright/cosmo_01.htm

David A. Smith

David,

Thank you! This has been bugging me for weeks.

I've read the links you supplied, and I think I basically follow. But
something's unclear to me:

You say that clocks now could be considered to be "running faster." I
had actually thought they would be "running slower."

Distant galaxies are more distant, because there's "more space"
between us and them now than before -- so, by analogy, I'd have
thought that there would be "more time" between two normally-locked
events (two "ticks" of an atomic clock), and that more time between
events would indicate a slow-down.

But it sounds like you have a geometric way of talking about this,
with the "flattening out" of space-time. Can I draw you out on that
point--?


Conrad.

Dear Conrad:

"Conrad" wrote in message
...
David,

Thank you! This has been bugging me for weeks.

I've read the links you supplied, and I think I
basically follow. But something's unclear to me:

You say that clocks now could be considered to
be "running faster." I had actually thought they
would be "running slower."

Which is why we linearize time, and let space (alone) take the
hit.

Distant galaxies are more distant, because there's
"more space" between us and them now than
before -- so, by analogy, I'd have thought that there
would be "more time" between two normally-locked
events (two "ticks" of an atomic clock), and that
more time between events would indicate a slow-down.

No. A slower clock generates "blue shifting", and greater
distance travelled by light per clock tick, which is the
*opposite* of expansion.

But it sounds like you have a geometric way
of talking about this, with the "flattening out" of
space-time. Can I draw you out on that point--?

Consider "gravitational time dilation". As you are "stationary"
in a location with high curvature (of spacetime), and compare
your clock to a "stationary" clock in a location that is in a
region of low curvature, you note that the clock in the low
curvature location "runs faster". The same should apply to the
Universe et al. An expanded Universe has lower overall curvature
than a smaller Universe.

http://en.wikipedia.org/wiki/Gravita..._time_dilation
.... as a short course...

David A. Smith

On May 26, 7:48*pm, "N:dlzc D:aol T:com \(dlzc\)"
wrote:
Dear Conrad:

"Conrad" wrote in message

...

David,

Thank you! *This has been bugging me for weeks.

I've read the links you supplied, and I think I
basically follow. *But something's unclear to me:

You say that clocks now could be considered to
be "running faster." *I had actually thought they
would be "running slower."

Which is why we linearize time, and let space (alone) take the
hit.

Distant galaxies are more distant, because there's
"more space" between us and them now than
before -- so, by analogy, I'd have thought that there
would be "more time" between two normally-locked
events (two "ticks" of an atomic clock), and that
more time between events would indicate a slow-down.

No. *A slower clock generates "blue shifting", and greater
distance travelled by light per clock tick, which is the
*opposite* of expansion.

But it sounds like you have a geometric way
of talking about this, with the "flattening out" of
space-time. *Can I draw you out on that point--?

Consider "gravitational time dilation". *As you are "stationary"
in a location with high curvature (of spacetime), and compare
your clock to a "stationary" clock in a location that is in a
region of low curvature, you note that the clock in the low
curvature location "runs faster". *The same should apply to the
Universe et al. *An expanded Universe has lower overall curvature
than a smaller Universe.

http://en.wikipedia.org/wiki/Gravita..._time_dilation
... as a short course...

David A. Smith

Excellent -- thank you!


Conrad.

I'm grappling with a cosmology question, and my internet research and
questioning has so far been in vain.

Briefly: *Is the ongoing expansion of the universe exclusively
spatial, or is time also expanding?

If so, what are the observable results? *If not, what causes time in
this case to be influenced differently than the spatial dimensions?
If the question is bogus, what are my faulty premises?

Any answers, direction, or resources would be appreciated.

Conrad.

I have built a model based on relativity to explain what this so
called
dark energy is that they relate to the expansion of the Universe.

It comes to two distant events, one observer and one explosion which
throws mass with near the speed of light toward the observer.

Light is the fastest. What is the first signal that the observer
receives?

The onset of the explosion.

What is the next signal that the observer receives?

The second moment after the explosion.

How fast will the observer see that mass moving from the onset of the
explosion?

Always under the speed of light.

When will that mass reach the observer?

In the visual frame, if the explosion happened 10 light years away,
the observer will see mass
approaching for at least 10 years.

But the explosion happened 10 years ago then, how come another 10
years is needed
for the mass to reach us, while in the local frame of the mass only 10
years passes for it
to reach the observer.

We find a relativistic warp everywhere in the Universe in terms of
what we see not corresponding
to their time. Time only happens locally, and when it goes
relativistic things warp.

One of the warps is that all the Universe is expanding away as a
result.

Try to put it together, 20 years pass for us, 10 years passes for the
mass that travels from
an explosion to us. Einstein discovered that the Universe is
relativistic.

We can't synchronize things exactly with distances and events.If
things warp in terms of
time, things also warp accordingly in terms of space. This cosmic
expansion is the
greatest example of such a thing happening.