Which direction are we traveling in space?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by John J. Bannan, Jul 6, 2007.

  1. John J. Bannan Registered Senior Member

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    If I am traveling south in my car, and the Earth is spinning East while traveling around the Sun, while the Sun is traveling around the Milky Way, while the Milky Way is traveling toward Andromeda, while the Universe is expanding, what is the net direction of travel?
     
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  3. mikenostic Stop pretending you're smart! Registered Senior Member

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    Doesn't that make about as much sense as if I were travelling in a spaceship going the speed of light, and I get up and walk towards the front of the spaceship, am I going faster than the speed of light?

    To answer your question, your net travel will still be the direction (i.e. circular) that the solar system is travelling around the center of the Milky Way. You may be travelling south on the earth, the earth may still be rotating and revolving around the sun, but those routes are still within the solar systems rotation around the center of the galaxy.
     
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  5. John J. Bannan Registered Senior Member

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    Yes, but the Milky Way is also traveling toward Andromeda. And, let's not forget that the Universe is expanding, too. So, you haven't answered the question.
     
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  7. Fraggle Rocker Staff Member

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    The velocity of each successively higher order of motion is so many orders of magnitude greater than the last lower one, that it makes the lower order insignificant for the purposes of calculating "direction" within the limits of our everyday measurements. Your car is moving south at 60mph, but if you're in one of the subtropical regions of the USA the highway you're on is moving east at around 900mph. The vector of your motion is not very far off from due east.

    But hold on, the speed of the earth in its orbit is about 67,000mph. I humbly confess that I don't know which way it's revolving in that orbit, but it hardly matters. Regardless of whether you're on the night side or the day side, that 1.5% contribution of the earth's rotation to your vector is not very significant to this discourse. Your vector is essentially identical to the earth's.

    The same goes for the orders-of-magnitude greater velocity of the solar system within the galaxy and of our galaxy within the universe. The effect of our planet's silly little circular movements to those vectors is about as significant as the speed of the fly crawling on your upholstery is to the vector of his motion in your moving car.

    Remember that the universe is expanding at a large fraction of the speed of light, perhaps even faster than that, if I could understand Walter Wagner's patient explanations. That's 670,000,000mph. All other motion pales in comparison.
     
  8. Communist Hamster Cricetulus griseus leninus Valued Senior Member

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    Which direction relative to what? There is no universal point of reference.
     
  9. John J. Bannan Registered Senior Member

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    If we are traveling at a large fraction of the speed of light, then are we experiencing any of the effects of near light speed travel? Is our time slower in comparison to some other place in the Universe? Are our bodies stretched?
     
  10. iceaura Valued Senior Member

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    Unless the expansion is uneven somehow, I can't see how it would affect the direction of motion. All directions would remain unaltered.

    So the velocity of the galaxy probably dominates. We're headed for Anrdomeda, with a tiny deflection to account for our current orbital velocity relative to the galactic center, and maybe an infinitesimal correction for our orbital velocity around the sun.

    We need a name for that direction, though. "Andromedoward" ? sounds like a camel. It is a long, dry journey - and we are in the company of Arabs - - -
     
  11. eburacum45 Valued Senior Member

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  12. (Q) Encephaloid Martini Valued Senior Member

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    You shouldn't be going by what Walter is telling you, as it is his own pet theory, not accepted theory nor what is observed. Anyone can find gobs of information explaining cosmology, yet you'll find nothing that backs up Walter's assertions.
     
  13. Dark520 Rebuilt Registered Senior Member

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    John brings up a good point; one which I would also like to hear an answer to... if anyone has an answer...
     
  14. (Q) Encephaloid Martini Valued Senior Member

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    We are NOT traveling at large fractions of c, that is complete nonsense. Our relative motion through space is nowhere near that, nor is anything else for that matter.
     
  15. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    It is irrelevant what our Milky Way galaxy's motion through the heavens is relative to other galaxies in our cluster. We are on board the Milky Way, and we will experience time in its reference frame.

    As 2Inquisitive has pointed out in the thread dumped into "pseudoscience" by Q [http://www.sciforums.com/showthread.php?t=68327&page=6], we can detect relative motion of the Milky Way [and a small contribution presumptively from the Solar System's motion within the Milky Way] towards the "great attractor", by observing a slight dipole anisotropy in the CMB, which 2inquisitive referred to as the "peculiar motion" of our galaxy relative to that CMB-emitter shell.

    And no, I do not subscribe to Q's pet theory that there are distant galaxies [those more than 1 billion light years away] that have relative net motions towards us [which if that were true, we'd see by way of a blue-shift in their spectral lines; and we only see red-shifts of spectral lines for very distant galaxies]. Since he has proposed his pet theory, which appears to be an extraordinary claim, I suggest he should post factual evidence of at least one distant galaxy that shows a blue-shift.

    The Wikipedia article is pasted below:

    From Wikipedia, the free encyclopedia
    Jump to: navigation, search
    The Great Attractor is a gravity anomaly in intergalactic space within the range of the Centaurus Supercluster that reveals the existence of a localised concentration of mass equivalent to tens of thousands of galaxies, observable by its effect on the motion of galaxies and their associated clusters over a region hundreds of millions of light years across.

    These galaxies are all redshifted, in accordance with the Hubble Flow, indicating that they are receding relative to us and to each other, but the variations in their redshift are sufficient to reveal the existence of the anomaly. The variations in their redshifts are known as peculiar velocities, and cover a range from about +700 km/s to -700 km/s, depending on the angular deviation from the direction to the Great Attractor.

    The first indications of a deviation from uniform expansion of the universe were reported in 1973 and again in 1978. The location of the Great Attractor was finally found in 1986 and lies at a distance of somewhere between 150 million and 250 million light years (the latter being the most recent estimate) from the Milky Way, in the direction of the Hydra and Centaurus constellations. That region of space is dominated by the Norma cluster (ACO 3627)[1], a massive cluster of galaxies, and contains a preponderance of large, old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves.

    Attempts to further study the Great Attractor and other phenomena are hampered due to line of sight obstruction by its location in the zone of avoidance (the part of the night sky obscured by the Milky Way galaxy).
     
  16. iceaura Valued Senior Member

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    From the link, it appears that the attractor is revealed not by our motion toward it, but by patterns in the relative Hubble shifts of galaxies influenced by it.

    Are we actually moving toward - getting closer to, over time - that thing?
     
  17. (Q) Encephaloid Martini Valued Senior Member

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    Nonsense, it is absolutely imperative what motion through space our galaxy is moving, as it invalidates your assertion that objects are hurtling through space at impossible speeds.

    We see those galaxies redshifted due to expansion, of which overshadows the relative motion of those galaxies. Many of them can very well have relative motions towards us, but we will still observe them redshifted.

    You won't see distant galaxies with blue-shifts. However, considering the FACT that there are local galaxies with varying directions gives rise to the prediction that distant galaxies should also have varying directions.

    You seem to think that our group of galaxies is the ONLY group in the entire universe with that remarkable trait. You refuse to accept even one other distant galaxy could possibly have similar varying motion through space.

    Are we therefore at the center of the universe, Walter? And ONLY our group of galaxies could possible have varying directions in space? Are you emphatically stating that one observed event in the universe couldn't possibly be happening anywhere else?

    Wonderful! First you completely ignore the linked Wikipedia article explaining the expansion of the universe and the cosmological redshift, and now you are sourcing it to make your point?
     
  18. (Q) Encephaloid Martini Valued Senior Member

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    And I'd like to know why you're derailing yet another thread with your pet theories?
     
  19. Fraggle Rocker Staff Member

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    I'm not sure what is the essence of the "pet theory" you refer to, but I have come across other articles that talk about "space" expanding at trans-light speeds because only "matter" is subject to that limitation and "space" is devoid of "matter." But then somehow the galaxy outboard of that expanded space has "moved" to a new location farther from me that I can only deconstruct as having exceeded the speed of light. It seems to me that I'm living through an era in which the boundary between physics and mathematics is blurring and it makes my head hurt.
    It was I who lamented the fact that I can't understand his explanations of this "expanding empty space" theory so you can blame me for this. And what I'm asking about is hardly any one person's "pet theory" since I have seen it elsewhere. It's hardly derailing this thread, which started off pretty whimsically and is still straddling the line between cosmology and existentialism. Which if you ask me is a pretty good description of 21st-century physics. So I suggest that you settle down, Beavis. I am not automatically predisposed to deciding that what Walter says is correct, but I will not be able to make that decision until I understand it and the gentleman is at least doing his best to help me do so.

    Fifty years ago I read a 150-page book with a title something like "Relativity for Precocious Teenagers" and I understood it. Is this "expanding empty space" thing going to be that hard? I'm probably not as precocious as I used to be. Ye who want me to decide that it's hogwash still have the obligation to help me understand it and make up my own mind. I can do that with reincarnation and Evolution Denialism so I expect to do it here too.
     
  20. (Q) Encephaloid Martini Valued Senior Member

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    That is correct, space did expand at faster than light speeds (inflationary period) because space is not subject to relativity, while matter is. That does not discount the fact that the matter/energy contained in the Big Bang was carried along with the expanding space. Again, relativity is not invalidated.

    The distant galaxies you observe that appear to be moving at c is a result of the expansion of space carrying those objects along, just like always, except that over time their relative motions through space have changed slightly. Our local galaxies are experiencing this change as they all move towards a larger mass; ie. Great Attractor. Therefore, we have direct observations of galaxies moving in a variety of directions.

    But, these galaxies are NOT flying through space at near light speeds. Here's why.

    Example: we have a line of sight in which galaxies are evenly spaced apart away from us at 100 million light years. Let's say that the space between our galaxy A and the next B (100 million light years) is expanding making it appear they are moving away from each other at 10,000 kph. The next galaxy C, is also moving away from B at 10,000 kph, which would make the speed between A and C 20,000 kph. The next galaxy D also appears to be moving away at 10,000 from C, 20,000 from B and 30,000 from A.

    A-----10,000kph-----B-----10,000kph-----C-----10,000kph-----D-----10,000kph---->
    A-----------------20,000kph--------------C
    A---------------------------30,000kph-------------------------D

    I think you can see the pattern. Once we are looking at galaxies billions of light years away, the appear to be moving away from us at huge speeds, but to galaxies near them, much smaller speeds.

    All of these galaxies actual relative motions through space are substantially smaller.

    Hence, we can easily deduce that a distant galaxy, even if it's relative motion through space is towards us will not appear blueshifted, simply because the expansion of space between us overpowers any local relative motion and they will appear redshifted.
     
  21. Fraggle Rocker Staff Member

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    And right there is where every one of you loses me. What actually does it mean to say that "space is expanding"? By definition there is nothing in space so--wait for it--nothing is expanding. Sorry, I'm the moderator of Linguistics so I couldn't help myself but I'm not trying to be facetious. Nothing means nothing.

    Is it correct to say that the only way I with my hypothetical telescope "know" that an empty space is "expanding" is by observing that the galaxy on the far side of it is farther away than it was the last time I looked? That can't possibly be, because we've only had telescopes for a few hundred years and I don't imagine the position of any galaxy has changed noticeably during that time. But if, for the sake of the argument, that is the reason for this assertion, where did the new explanation come from that the empty space is expanding, when Occam's Razor would suggest that we first examine the simpler hypothesis that the galaxy on the other side is simply moving really really fast? Is there some mystical property of the empty space that allows us to measure the size of nothing and nod our heads in sage agreement that yup, nothing is bigger than it was last time we looked?

    The time-tested way to measure the size of an empty space is to measure the distance between the two closest objects on either side of it. If we come back tomorrow and discover that they are further apart, we don't say, "Good goddess, the space has expanded, call CNN!" We say, "Which one of you jokers moved the red marker?"

    This is why I state that physics has become blurred with mathematics and cosmology has become blurred with existentialism. And this is what I need to understand.

    I don't know how many other moderators are valiantly trying to follow these threads, but I've got at least a modicum of credentials with my aborted Caltech education back in the days when the hottest new scientific discovery was DNA. Speaking from this position I'm not comfortable watching two guys get into an argument over something that apparently no one else here understands completely but a lot of us are interested in, and the guy with the key to the Moderator's Executive Restroom pulls rank. Quite a few members were getting something out of the thread on "Looking at the Start of the Universe" and don't quite understand why it got reclassified as Pseudoscience.

    I do not claim to have never abused my Restroom Key and geeze I've only had it for a few months. But there are lots of people here who can slap me upside the head when I spout off about Christianity being junk science, call the anti-immigration lobby a bunch of white supremacists, and deny men the right to an opinion about abortion until one of us gets pregnant. There appears to be nobody here who can peer-review your and Walter's disagreeable views on cosmology. I think that unfortunately places the heavy burden on you to have the argument in public and let us do our best to understand both sides. We don't know from our passing familiarity with the subject that one of you is the pseudoscientist and the other is the real one. The Scientific Method mandates that we be given whatever it takes to understand that, and absolutely not take it on authority.
     
  22. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Iceaura:

    You are correct, the Wikipedia article references numerous galaxies and clusters that are moving towards the "great attractor", as revealed by their red-shifts not being exactly as expected if there were no additional motion. It does not state that the Milky Way is also moving towards the "great attractor". However, I presumed that to be the case, which presumption might be incorrect. We do know that there is relative motion of the Milky Way relative to the CMB as revealed by the slight dipole anisotropy of the CMB; I haven't read yet whether that relative motion is generally towards the "great attractor", though I presume that a large portion of the direction vector is in that general direction. That information should be available, and I would appreciate any direct links to the direction of our dipole anisotropy, as compared to the direction of the "great attractor". It's probable that there are a multiple of factors pulling on the Milky Way, and the direction is not entirely in that of the "great attractor".

    Q:

    You are finally beginning to be a little more articulate in your posts.

    You wrote:

    Hence, we can easily deduce that a distant galaxy, even if it's relative motion through space is towards us will not appear blueshifted, simply because the expansion of space between us overpowers any local relative motion and they will appear redshifted. [bold added for emphasis]

    That is exactly what I have been stating - - namely, that the relative motion of a galaxy within a receding cluster of galaxies might be in our direction, relative to the cluster as a whole, but the net result is that we see a red-shift, because the cluster as a whole is receding, and its recessional velocity [which you contend is caused by "inflation" or "expansion" of space, but which I contend is caused by motion through space] is far greater than [overpowers, in your terminology] the relative motion of the galaxy within that cluster in our direction. Only in very nearby galaxies would the relative motion of a cluster be possibly greater than the recessional velocity of that cluster; and in those rare cases of nearby galaxies we would see the galaxy as blue-shifted rather than red-shifted.

    You also wrote:

    That is correct, space did expand at faster than light speeds (inflationary period) because space is not subject to relativity, while matter is. That does not discount the fact that the matter/energy contained in the Big Bang was carried along with the expanding space. Again, relativity is not invalidated.

    That is, of course, the "prevailing view" of many cosmologists, which you have repeated. The net result is that an object has moved from Point A to Point B at faster than the speed of light, due to the presumed "expansion of space" between them, which is a mathematical crutch used to circumvent the speed of light being a constant. I contend that that is bogus, and introduces a novel concept for which there exists no experimental evidence. It doesn't matter how many get on the bandwagon and accept it, it does not necessarily make it correct.

    You also wrote:

    You seem to think that our group of galaxies is the ONLY group in the entire universe with that remarkable trait. You refuse to accept even one other distant galaxy could possibly have similar varying motion through space.

    No, that is not correct. That is not what I "seem to think". I expect that every local cluster of galaxies will have a wide variety of direction of motion of each galaxy within it, relative to that cluster. Because all such clusters except for those that are nearby are receding from us at high velocity, all of those galaxies within those clusters will have a net recessional velocity, relative to us. We can, however, determine by the variations of the red-shifts within that cluster, what the relative motions are of those galaxies, or indeed, even of the entire cluster, if there is some additional direction imparted to it. That is how the "great attractor" was located.

    And no, I have not said the galaxies are receding at close to c. Their recessional velocities are substantially below c. Only once you get to the farthest galaxies [circa 9 billion light-years distant, the last I read as being the most distant observable galaxy] is the recessional velocity coming to an appreciable percentage of c. Way beyond that, the CMB-emitter is moving at a very high percentage of c, roughly 0.9999991 c. We can presume that our region, and every other region, of our Universe once looked like that matter as we see it in our reference frame; namely a hot plasma of 2,700 degrees K, expanding and cooling. I will leave it as an exercise for you to calculate the red-shift and recessional velocity of galaxies at 1 billion light-years, 3 billion light-years, and 9 billion light-years distance.
     
  23. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

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    Fraggle Rocker:

    I agree wholeheatedly with your post #18.
     

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