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One way or another
2014-Jul-03, 09:08 PM
I would like some input on the following, that I wrote, thank you.

Red shift blue shift

Galaxies have different trajectories. If the galaxy is moving at a different angle than our galaxy, it will always be in red shift, from my thinking. If a galaxy has the same angle or line that our Galaxy has, while we are moving towards each other or let's say we are moving towards them faster than they are moving away from us, we will see them in blue shift.

EigenState
2014-Jul-03, 11:33 PM
Greetings,


I would like some input on the following, that I wrote, thank you.

Red shift blue shift

Galaxies have different trajectories. If the galaxy is moving at a different angle than our galaxy, it will always be in red shift, from my thinking. If a galaxy has the same angle or line that our Galaxy has, while we are moving towards each other or let's say we are moving towards them faster than they are moving away from us, we will see them in blue shift.

Your analysis is not correct.

A wavelength shift is observed only corresponding to the radial component of the relative motion. That is. motion along the direct line of sight between the two objects.

If two objects are moving away from each other along that line of sight, there is an observed redshift. If they are moving towards each other along that line of sight there is a blueshift.

Best regards,
ES

Hornblower
2014-Jul-03, 11:47 PM
I would like some input on the following, that I wrote, thank you.

Red shift blue shift

Galaxies have different trajectories. If the galaxy is moving at a different angle than our galaxy, it will always be in red shift, from my thinking. If a galaxy has the same angle or line that our Galaxy has, while we are moving towards each other or let's say we are moving towards them faster than they are moving away from us, we will see them in blue shift.My bold. By that line of thought, two cars on crossing roads always will be getting farther apart, even if they are on a collision course while approaching an intersection. Please try to clarify what you mean by "moving at a different angle."

Jens
2014-Jul-04, 02:06 AM
I wrote some explanations, but somehow I get the feeling that you are trying to envision motion in relation to a fixed frame, for example cars moving on a (fixed) highway on the earth. If you get rid of that fixed frame, I think it makes it easier to understand.



Galaxies have different trajectories. If the galaxy is moving at a different angle than our galaxy, it will always be in red shift, from my thinking.

I think you should think of it more simply. If the distance between us and the galaxy is increasing, then it will be red-shifted. If the distance is decreasing, it will be blue-shifted.


If a galaxy has the same angle or line that our Galaxy has, while we are moving towards each other or let's say we are moving towards them faster than they are moving away from us, we will see them in blue shift.

I'm not sure what you mean by "the same angle," but I would point out that in the latter part of the sentences, the two things separated by "or" mean the same thing. "We are moving toward them faster than they are moving away from us" means "we are moving toward each other." Or rather, something *can't* be moving away from you if you are moving toward it. If you are moving toward it, it *must* be moving toward you as well. If I am approaching another object as a speed of say 5 km/h, then the other object must be moving toward me at 5 km/h as well. There's just no way to get around that.

Jeff Root
2014-Jul-04, 08:17 AM
Jens,

The last bit of what you said probably wouldn't make sense to
someone who thinks of speeds only in terms of speed relative
to the ground they are travelling over. The original poster may
be imagining galaxies travelling along highways in space.

-- Jeff, in Minneapolis

One way or another
2014-Jul-04, 11:22 AM
Greetings,



Your analysis is not correct.

A wavelength shift is observed only corresponding to the radial component of the relative motion. That is. motion along the direct line of sight between the two objects.

If two objects are moving away from each other along that line of sight, there is an observed redshift. If they are moving towards each other along that line of sight there is a blueshift.

Best regards,
ES

Let's say two people are standing side-by-side and one is walking straightahead, while the other is walking at a 15 angle. Would that person be in red shift or blueshift?

George
2014-Jul-04, 09:15 PM
Let's say two people are standing side-by-side and one is walking straightahead, while the other is walking at a 15 angle. Would that person be in red shift or blueshift? Objects moving away from one another will produce a redshift, opposite for blueshift. Simply ask if the observer is seeing one or the other, or no relative motion at all. Objects moving at angles can be broken into two component vectors, the logical choice is to have one vector parallel to the observer's path and the other perpendicular. The latter vector component is the key to redshift measurement.

One way or another
2014-Jul-04, 09:22 PM
So if the path is perpendicular, from your relative point of view, will we see that galaxy in red shift or blueshift and why?

EigenState
2014-Jul-04, 09:32 PM
Greetings,


Let's say two people are standing side-by-side and one is walking straightahead, while the other is walking at a 15 angle. Would that person be in red shift or blueshift?

Your question lacks self-consistency. If two people are "standing side-by-side" they cannot be walking away from each other. You also failed to specify the magnitudes of the velocities thus making it impossible to provide a numerical answer.

The angle between the directions of motion of two bodies can be broken down utilizing simple geometry to give the radial component of the relative velocities. The radial component of that velocity is nothing more than the speed at which the two objects separate, or approach along the straight line connecting those two bodies. The wavelength shift depends only on that radial velocity component.

Best regards,
ES

Hornblower
2014-Jul-04, 10:53 PM
Let's say two people are standing side-by-side and one is walking straightahead, while the other is walking at a 15 angle. Would that person be in red shift or blueshift?

It depends in part on whether that angle is converging or diverging.

Strange
2014-Jul-04, 10:58 PM
So if the path is perpendicular, from your relative point of view, will we see that galaxy in red shift or blueshift and why?

Are they getting closer together or further apart?

Jens
2014-Jul-04, 11:50 PM
Let's say two people are standing side-by-side and one is walking straightahead, while the other is walking at a 15 angle. Would that person be in red shift or blueshift?

The answer is red-shifted. Just imagine that there is no pavement. The two people will get further away from each other over time, which is all that matters. Red shift happens when the distance between tow objects is increasing, period. It doesn't master what the vectors are.

One way or another
2014-Jul-05, 12:30 AM
It depends in part on whether that angle is converging or diverging.

Yes, that is correct. Thank you.

So if blueshift denotes convergence and red shift denotes divergence, the universe cannot be expanding as science claims, when we see both, from my perspective.

One way or another
2014-Jul-05, 12:35 AM
The answer is red-shifted. Just imagine that there is no pavement. The two people will get further away from each other over time, which is all that matters. Red shift happens when the distance between tow objects is increasing, period. It doesn't master what the vectors are.

Yes, exactly. However, it is claimed in some circles, that redshifts means that our universe is expanding. From my perspective, that seems wrong.

slang
2014-Jul-05, 09:09 AM
So if blueshift denotes convergence and red shift denotes divergence, the universe cannot be expanding as science claims, when we see both, from my perspective.

Careful. This is very much against mainstream science. It's ok to ask about this, to better understand why "science claims expansion", however if you start promoting the notion that expansion is not happening we will move this discussion the the ATM sub-forum. Special rules apply there, and you would be required to support the claim with math and/or evidence. I think you're asking, not promoting, so please be careful to keep it that way.

Jens
2014-Jul-05, 09:21 AM
So if blueshift denotes convergence and red shift denotes divergence, the universe cannot be expanding as science claims, when we see both, from my perspective.

Science doesn't claim that. The observations suggest it. There are a small number of galaxies that are blue shifted, all relatively nearby, but the overwhelming majority are red shifted, and the farther away they are, the redder they are...

Jeff Root
2014-Jul-05, 09:33 AM
So if blueshift denotes convergence and red shift denotes
divergence, the universe cannot be expanding as science
claims, when we see both, from my perspective.
Is your perspective different from that of everyone else?

-- Jeff, in Minneapolis

Cougar
2014-Jul-05, 11:40 AM
So if blueshift denotes convergence and red shift denotes divergence, the universe cannot be expanding as science claims, when we see both, from my perspective.

Yes, we see both red and blue shifted objects. But are they distributed in any particular way, or is it all just random, some red some blue? The answer, discovered in, like, 1927, is that only relatively nearby objects are blueshifted, and this would be due to the local gravitational effects pulling nearby objects closer together. Objects farther away than those in the Local Group (http://www.atlasoftheuniverse.com/localgr.html) of galaxies are all redshifted. And as Jens mentions, as more and more distant objects are observed, we measure greater and greater redshifts - all nearly in direct proportion to their distance. That's why we conclude the universe must be expanding.

EigenState
2014-Jul-05, 12:23 PM
Greetings,


So if blueshift denotes convergence and red shift denotes divergence, the universe cannot be expanding as science claims, when we see both, from my perspective.

Your conclusion regarding the angular dependence appears to be nothing more than a qualitative statement regarding the decomposition of the velocity vectors to yield the relative radial velocity component--but then you have not stated the functional form of the angular dependence.

As stated, your interpretation does not, indeed cannot provide quantitative predictions of the wavelength shifts as could be easily demonstrated via laboratory spectroscopic measurements utilizing atomic or molecular beams.

Best regards,
ES

Reality Check
2014-Jul-08, 02:07 AM
However, it is claimed in some circles, that redshifts means that our universe is expanding.
That is not really the claim in any circle, One way or another :).
The observation that galaxies are red shifted means that the galaxies are receding from us and that is all.
Add to this Hubble's observation that galaxies have higher red shift with distance then the most likely explanation is that the universe is expanding. That the universe is expanding is actually based on a body of evidence that includes Hubble's Law, the CMB and other observations (http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence).

ShinAce
2014-Jul-08, 05:19 AM
The observation that galaxies are red shifted means that the galaxies are receding from us and that is all.


Galaxies being redshifted is the observation which you cannot deny, since you can test it yourself. What that means depends on who's talking.

If you ask Erik Verlinde, he'd tell you it's a mix of the holographic principle and thermodynamics which gives rise to the apparent expansion, and its acceleration, of the universe.
See:
http://arxiv.org/abs/1001.0785 "On the Origin of Gravity and the Laws of Newton"
http://arxiv.org/abs/1001.3470 "Friedmann Equations from Entropic Force"
http://arxiv.org/abs/1002.4278 "Entropic Accelerating Universe"
http://arxiv.org/abs/1003.4526 "Entropic cosmology: a unified model of inflation and late-time acceleration"
http://arxiv.org/abs/1001.4786 "Towards a Holographic Description of Inflation and Generation of Fluctuations from Thermodynamics"

In the same vein of Einstein demoting gravity from a force, we might actually see dark energy being demoted from energy.

Cougar
2014-Jul-08, 12:56 PM
If you ask Erik Verlinde...

If you ask Lubos Motl about Erik Verlinde, he'd say:



I know Erik Verlinde rather well, in person, and so do most of the people who have politely suggested that he has gone off the deep end. And I am actively aware of lots of his nontrivial previous work (having co-discovered some of it), and so are the other folks. But this personal familiarity can't have any impact on our ability to realize that the paper doesn't agree with the experimentally known physics of gravity. Science is or must be meritocracy, not nepotism. - The Reference Frame (http://motls.blogspot.com/2012/06/george-mussers-occult-musings-on-erik.html)

tusenfem
2014-Jul-08, 01:41 PM
Okay, let's not get too side-tracked with these discussions.
For the OP question it is good enough that red-shifted galaxies with the Hubble relationship shows that the universe is expanding, we need not delve into the ideas of Verlinde or what his colleagues think of him.

One way or another
2014-Jul-08, 08:42 PM
By the answers I am receiving, it seems very likely. What do you think?

One way or another
2014-Jul-08, 08:45 PM
That is all based on whether or not white can actually travel billions of light-years. From what our sun proves, that is not possible.

One way or another
2014-Jul-08, 08:47 PM
Is your perspective different from that of everyone else?

-- Jeff, in Minneapolis

From some of the answers I am getting, yes. However I'd like to know what you think.

One way or another
2014-Jul-08, 08:50 PM
That is not really the claim in any circle, One way or another :).
The observation that galaxies are red shifted means that the galaxies are receding from us and that is all.
Add to this Hubble's observation that galaxies have higher red shift with distance then the most likely explanation is that the universe is expanding. That the universe is expanding is actually based on a body of evidence that includes Hubble's Law, the CMB and other observations (http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence).

Everything that is claimed even by hubble, is predicated on whether or not light can travel billions of light-years. That cannot be proven. Science will not even attach a light to any of its probes and fire those probes lights back towards the earth, in an effort to prove such.

korjik
2014-Jul-08, 08:55 PM
Everything that is claimed even by hubble, is predicated on whether or not light can travel billions of light-years. That cannot be proven. Science will not even attach a light to any of its probes and fire those probes lights back towards the earth, in an effort to prove such.

Every space probe has had a light on it that transmits back toward the earth.

antoniseb
2014-Jul-08, 08:57 PM
That is all based on whether or not white can actually travel billions of light-years. From what our sun proves, that is not possible.
What is all based on that? Also, what do you mean "white can actually travel"? Once you fill us in on that, kindly explain how our Sun proves that whatever you meant can't be done.

EigenState
2014-Jul-08, 09:03 PM
Greetings,


Everything that is claimed even by hubble, is predicated on whether or not light can travel billions of light-years. That cannot be proven. Science will not even attach a light to any of its probes and fire those probes lights back towards the earth, in an effort to prove such.

The observed spectra of distant quasars is insufficient evidence for the propagation of light through space for vast distances?

Emphasis added. And the microwave communication systems linking those probes and Earth bound control centers do not constitute light (in the broadest sense)?

Best regards,
ES

One way or another
2014-Jul-08, 09:03 PM
Science could use green laser light from any probe and focus it back towards earth, let's say to the farther is reaches of any probe and see if it makes it back to Earth. From the light tests done from the earth to the moon and back, I see no possibility of that.

If as science claims, we should challenge everything, then should we not look at science in such a way? If we are not willing to first challenge everything that science claims, then we are just copy and pasting everything that science does claim, correct?

PetersCreek
2014-Jul-08, 09:07 PM
One way or another (and others) this discussion is taking place in the Space/Astronomy Questions and Answers forum. This is where you ask questions and get mainstream answers. You may not argue those answers on an against-the-mainstream basis. You currently have an ATM thread open where you can make your ATM claims. Don't do it here.

One way or another
2014-Jul-08, 09:08 PM
What is all based on that? Also, what do you mean "white can actually travel"? Once you fill us in on that, kindly explain how our Sun proves that whatever you meant can't be done.

Lol, ok, white, should be light.
I'll be back a little later to explain.

Jeff Root
2014-Jul-08, 09:08 PM
Your original statement and your questions which followed it
in your next posts showed that you have no understanding of
motion, so your understanding of how Doppler shift works is
completely messed up. You don't understand what it is or
how it is observed and measured. The other people who have
replied in this thread all have a good understanding of motion
and Doppler shift. So your perspective is different from that
of everyone else in this thread.

-- Jeff, in Minneapolis

Amber Robot
2014-Jul-08, 09:12 PM
It is incorrect to say that our space probes haven't been sending light back to Earth. However, that can't prove that light can travel billions of light years, because no Earth probe has traveled that far. There is an underlying assumption to our investigation of the universe that the laws of physics operate the same anywhere in the universe. Of course we can't prove that, because we can't probe physics everywhere in the universe. But it's more about building a framework and applying to all that we can observe. And there's nothing to suggest that light can't travel billions of light years. In fact, there are strongly supported theories that suggest that it can and does. Any theory that attempts to upend the current theories would need to do at least a good a job at predicting the observables as our current theories do.

Jeff Root
2014-Jul-08, 09:18 PM
In addition to not understanding motion or Doppler shifting,
it appears that you also do not understand that radio waves
are light.

-- Jeff, in Minneapolis

PetersCreek
2014-Jul-08, 09:48 PM
In addition to not understanding motion or Doppler shifting,
it appears that you also do not understand that radio waves
are light.

This is just one example of responses that continue to address the ATM claims and not the OP question. I'll take that to mean that the OP has been adequately addressed and that the ATM thread on this topic will receive a few more visitors...since this one is now closed.