michel123456 Posted November 29, 2014 Posted November 29, 2014 Because the distance between them has increased. In the past they were closer together. That doesn't seem too hard to understand. It is difficult to me to understand that because it goes against what we observe. What we observe are galaxies further and further away from each other as much as we look in the past. Don't you realize that?
Strange Posted November 29, 2014 Posted November 29, 2014 It is difficult to me to understand that because it goes against what we observe. What we observe are galaxies further and further away from each other as much as we look in the past. I don't know if this can be explained except with the mathematical model. You are not seeing a snapshot of the universe as it was in the past. You are seeing it with the effects of expansion. In other words, those galaxies were closer together when the light was emitted (for example, the furthest galaxies we see were only about 4 billion light years away). But they appear further apart now because space has been expanding during the time it took light to get here.
michel123456 Posted November 29, 2014 Posted November 29, 2014 (edited) I don't know if this can be explained except with the mathematical model. You are not seeing a snapshot of the universe as it was in the past. You are seeing it with the effects of expansion. In other words, those galaxies were closer together when the light was emitted (for example, the furthest galaxies we see were only about 4 billion light years away). But they appear further apart now because space has been expanding during the time it took light to get here. O.K. But still the amount of distance is not so important for the concept. We never observe more distant galaxies closer to each other. i mean, when distance increases, time increases too. So the further we look in the past, the more far away is the galaxy. The concept is the same with or without expansion. There is never a situation where more ancient galaxies on diametrically opposite sides of our observable universe are closer to each other. --------------------------------- The past is sread out around us. as much we look into the past, the more the sphere of the observable universe gets large. We never observe ancient galaxies getting close & closer to each other. Edited November 29, 2014 by michel123456
Mordred Posted November 29, 2014 Posted November 29, 2014 (edited) Think of it this way the further we look the more dense the universe becomes. Thus the universe also becomes hotter. Ie the CMB at 3000 Kelvin. Galaxies included. Remember baryonic matter is only a small contributor to the energy budget of the universe. The term recessive velocity and its superluminal measurement is very misleading. We're stuck with it but it's far more misleading than what it is worth. The term accelerating expansion is a result of recessive velocity. It is based on geometry. Take that 10 cm ruler. Let's apply simple numbers. Say there is a galaxy at each centimeter dividend. Now increase the distance between each galaxy by 1mm (10% the total volume) So second two has a total volume of 11 cm to start now add 10% for new total of 12.1 cm. Then add 10 % of that the next second and so forth. See how it has an accelerating exponential expansion. However per 1" divident the change remains 1mm per second per inch. Or 10% of each centimeter. Hope this helps. Keep in mind the space between each of the original coordinates all change equally in every direction. Ie if you did the same thing with two rulers to represent 2d or 3 rulers to represent ,3d with no change of angles between any of the galaxies or rulers Notice the rate of change remains 10% per volume. This is the same as Hubbles constant 70 km/sec/Mpc. However the rate of change in the recessive velocity will be accelerating. By 10% of the total volume between any two galaxies of the previous second. Edited November 29, 2014 by Mordred 1
michel123456 Posted November 29, 2014 Posted November 29, 2014 Think of it this way the further we look the more dense the universe becomes. Do you have some evidence?
Strange Posted November 29, 2014 Posted November 29, 2014 Do you have some evidence? http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence The trouble is, you are treating what we see as the way the universe was then. But that doesn't take expansion into account. Those widely separated galaxies were much closer together (i.e. the universe was denser) when the light left them. The further back/away we look the more expansion has taken place and so the more "correction" must be done to calculate what the actual density was then; in other words, the further back we look, the more dense it was but the less dense it appears now. This answer is kind-of related: http://www.astro.ucla.edu/~wright/cosmology_faq.html#DN 1
michel123456 Posted November 29, 2014 Posted November 29, 2014 in other words, the further back we look, the more dense it was but the less dense it appears now. Thank you. I'll keep "the less dense it appears now" as the evidence. BTW this evidence is not listed in your link http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence And the statement "the further we look the more dense the universe becomes" is wrong.
Strange Posted November 29, 2014 Posted November 29, 2014 Thank you. I'll keep "the less dense it appears now" as the evidence. You can ignore all the evidence for expansion and misinterpret things that way if you want. It's a bit sad, but it's your choice. BTW this evidence is not listed in your link http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence That is evidence for the model. The model that tells us that the universe is denser in the past. And the statement "the further we look the more dense the universe becomes" is wrong. Apparently not.
michel123456 Posted November 29, 2014 Posted November 29, 2014 The further we LOOK. Evidence (what we look at)says that galaxies are further apart. You transform this evidence into its contrary because you prefer the model. How do you call that methodology in science? -2
Endy0816 Posted November 29, 2014 Posted November 29, 2014 Redshift. If you go by your own requirement of observation then expansion is the logical conclusion based on this light.
Strange Posted November 29, 2014 Posted November 29, 2014 The further we LOOK. Evidence (what we look at)says that galaxies are further apart. You transform this evidence into its contrary because you prefer the model. How do you call that methodology in science? Science is the process of building models to describe the world around us, based on the evidence, and then testing those models against further evidence.
Mordred Posted November 29, 2014 Posted November 29, 2014 (edited) Do you have some evidence? You also aren't considering that the CMB is measured accurately. At 3000 Kelvin in the past. Then consider how the ideal gas laws work. A higher density means a higher temperature. Edited November 29, 2014 by Mordred
Ophiolite Posted November 29, 2014 Posted November 29, 2014 The further we LOOK. Evidence (what we look at)says that galaxies are further apart. You transform this evidence into its contrary because you prefer the model. How do you call that methodology in science? Earlier I asked you this: Are you unable to understand this, or do you not want to understand this? I am curious. Both of you appear to be using the argument of personal incredulity You chose not to reply. Perhaps you did not see the post. Will you reply this time, or will you leave me little alternative than to consider that you are trolling?
michel123456 Posted November 29, 2014 Posted November 29, 2014 (edited) Earlier I asked you this: Are you unable to understand this, or do you not want to understand this? I am curious. Both of you appear to be using the argument of personal incredulity You chose not to reply. Perhaps you did not see the post. Will you reply this time, or will you leave me little alternative than to consider that you are trolling? I am unable to understand how a far away galaxy as seen from the East was together with a far away galaxy as seen from the west, a long time ago, because the process that we actually observing is exactly the contrary: the older, the more far away. Edited November 29, 2014 by michel123456
Mordred Posted November 29, 2014 Posted November 29, 2014 (edited) It's amazing though I and others post numerous articles including peer reviews. My signature also contains free peer reviewed textbooks. As well as provides An expansion and redshift calculator. Yet you choose to ignore this wealth of information . The LCDM (hot big bang model with cold dark matter and the cosmological constant.). Is a model that is continously being tested by observations. That data set and model gets tested with every observation made every single day that provides new data. As mentioned there is also redshift. I already provided an article explaining in simple terms what that means. Please take the time to read the links I provided. Especially the one titled. "What we have learned from Observational evidence" http://arxiv.org/abs/1304.4446 Edited November 29, 2014 by Mordred
michel123456 Posted November 29, 2014 Posted November 29, 2014 We do NOT observe the older, the more close together. 1
Strange Posted November 29, 2014 Posted November 29, 2014 (edited) the process that we actually observing is exactly the contrary Only if you (deliberately?) misinterpret the evidence. "People must get smaller as they get further away. Just look, they LOOK smaller!" Edited November 29, 2014 by Strange
michel123456 Posted November 29, 2014 Posted November 29, 2014 I wonder if any of you want to understand my objection. What we observe is a universe that is huge. The more we look in the past, the more huge it is. The conclusion we get from this very obvious information is that in the past, the universe was smaller. Don't you see any contradiction here? Am I the only one living on this Forum?
Mordred Posted November 29, 2014 Posted November 29, 2014 That is not what you are measuring. When we look further back in time we see a higher density. We see the thermodynamic laws that form the basis of big bang nucleosynthesis. We see the predicted quantities of elements in particular hydrogen and lithium. We see different stars type 1a that can only form as a result of a higher density. We see the CMB which is a prediction of the big bang model. We see a higher number of quasars which is a result of a higher energy density in the past. We see the redshift of the light from those objects. We SEE plenty of evidence that supports an expanding universe. You choose to ignore all of that evidence. You fail to take the time to study the tools that will teach you why we know the universe is expanding. Google Hubble for example. Remember he observed and measured galaxies moving away from each other. If you refuse to look at the info provided then believe whatever unicorns suit your fancy 1
Strange Posted November 29, 2014 Posted November 29, 2014 Don't you see any contradiction here? If I came across a contradiction in something that is almost universally accepted then I would assume I have misunderstood, rather than that I have spotted something trivial that all the greatest minds of the last hundred years have missed.
Mordred Posted November 29, 2014 Posted November 29, 2014 If I came across a contradiction in something that is almost universally accepted then I would assume I have misunderstood, rather than that I have spotted something trivial that all the greatest minds of the last hundred years have missed. Same here I would also take the time to study why a model states what it does before discounting it.
MigL Posted November 30, 2014 Posted November 30, 2014 (edited) Ooooo, that's harsh, Ophiolite I think he's a little confused, we've all been there. Michel123456, consider a volume of space, say 100 mil LY radius around us, and note the density of galaxies as well as their make-up. Now take a look at a field of roughly the same spherical volume, but at a distance of say 4.9 to 5.1 bil LY from us, in any direction ( it doesn't matter ). Is the density of galaxies in that volume greater than the first volume, immediately surrounding us ? Are a lot of the galaxies elliptical rather than spiral with a predominance of active. black hole cores ( quasars ) ? Is the composition of these galaxies primarily younger generation stars, and a lot more gas clouds? These ( and others Mordred has listed ) are the observations which tell us the universe has expanded since 5 bil years ago. What evidence do you have to the contrary ? Edited November 30, 2014 by MigL
Mordred Posted November 30, 2014 Posted November 30, 2014 [latex]{\small\begin{array}{|c|c|c|c|c|c|}\hline R_{0} (Gly) & R_{\infty} (Gly) & S_{eq} & H_{0} & \Omega_\Lambda & \Omega_m\\ \hline 14.4&17.3&3400&67.9&0.693&0.307\\ \hline \end{array}}[/tex] [tex]{\small\begin{array}{|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|} \hline a=1/S&S&T (Gy)&R (Gly)&D_{now} (Gly)&D_{then}(Gly)&D_{hor}(Gly)&V_{now} (c)&V_{then} (c) \\ \hline 0.001&1090.000&0.0004&0.0006&45.332&0.042&0.057&3.15&66.18\\ \hline 0.003&339.773&0.0025&0.0040&44.184&0.130&0.179&3.07&32.87\\ \hline 0.009&105.913&0.0153&0.0235&42.012&0.397&0.552&2.92&16.90\\ \hline 0.030&33.015&0.0902&0.1363&38.052&1.153&1.652&2.64&8.45\\ \hline 0.097&10.291&0.5223&0.7851&30.918&3.004&4.606&2.15&3.83\\ \hline 0.312&3.208&2.9777&4.3736&18.248&5.688&10.827&1.27&1.30\\ \hline 1.000&1.000&13.7872&14.3999&0.000&0.000&16.472&0.00&0.00\\ \hline 3.208&0.312&32.8849&17.1849&11.118&35.666&17.225&0.77&2.08\\ \hline 7.580&0.132&47.7251&17.2911&14.219&107.786&17.291&0.99&6.23\\ \hline 17.911&0.056&62.5981&17.2993&15.536&278.256&17.299&1.08&16.08\\ \hline 42.321&0.024&77.4737&17.2998&16.093&681.061&17.300&1.12&39.37\\ \hline 100.000&0.010&92.3494&17.2999&16.328&1632.838&17.300&1.13&94.38\\ \hline \end{array}}[/latex] See if this works here Nope guess not tried posting the cosmocalc in my Sig... works on other forums just not this one
DimaMazin Posted November 30, 2014 Author Posted November 30, 2014 This math is still wrong. It does not account for expansion. You evidentally didn't read my post in regards to the Hubble sphere and cosmological event horizon ( observable universe) The proper distance to a stellar object is given by [latex]Proper distance =\frac{\stackrel{.}{a}(t)}{a}[/latex] a is the scale factor. The dot above represents the scale factor today. See my earlier posted articles for clarification. To clarify this we can see objects with an apparent recessive velocity at z=1090 of 3c . However the object is not moving at 3c . Recessive velocity is a distance dependant measurement. Hubble's law states " the greater the distance the greater the recessive velocity." [latex]v_{recessive}=H_oD[/latex] Locally light can overcome the rate of expansion 70 km/s/Mpc. At each Mpc divident the rate of expansion is no obstacle. Recessive velocity becomes greater than c past the Hubble sphere. However that measurement is total distance between us and the Hubble sphere. It is an apparent not an actual velocity. All of this is covered in the article I posted earlier. http://tangentspace.info/docs/horizon.pdf However as the universe is flat S(k)=0. You can use the 4d distance formula of the FLRW metric conniving distance equation. (In the notation from Barbara Ryden "Introductory to Cosmology" [latex]d{s^2}=-{c^2}d{t^2}+a{t^2}[d{r^2}+{Sk}{r^2}d\Omega^2][/latex] [latex]S\kappa r= \begin{cases} Rsin ,r/R & k=+1\\ r & k=0\\ Rsinh,r/R & k=-1 \end {cases}[/latex] See the universe geometry article below its 2 pages http://cosmology101.wikidot.com/universe-geometry The link to page two is http://cosmology101.wikidot.com/geometry-flrw-metric/ This breaks down the distance measures in 2d 3d and 4d with the FLRW metric. The first page describes what is meant by flat or curved universe geometry. The second page shows the metrics in each case. Flat, positive or negative curved. The difference between commoving and proper can be found here http://en.m.wikipedia.org/wiki/Comoving_distance You will note Another varient on the commoving distance formula both are compatible I dont doubt the evidences. I don't understand the communication with relativity. How do you define kinetic energy and momentum of an escaping galaxy?
Strange Posted November 30, 2014 Posted November 30, 2014 I dont doubt the evidences. I don't understand the communication with relativity. The connection with GR is that is the theory that is used to describe the universe (the nature of space-time). It is, therefore, the theory that predicted the expansion of the universe (which was later confirmed by observation): The Friedmann–Lemaître–Robertson–Walker (FLRW) metric is an exact solution of Einstein's field equations of general relativity; it describes a homogeneous, isotropic expanding or contracting universe http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric How do you define kinetic energy and momentum of an escaping galaxy? I am curious why you ask this. I suppose you could define the kinetic energy and momentum in the same way you would for any other object. But I'm not sure it has any real meaning, because the apparent movement is purely due to the metric expansion of space. 1
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