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Post by mak2 on Jan 15, 2012 16:49:11 GMT 1
You need to define exactly what space is and prove that photons can be "stretched" by it expanding. It is a rather ridiculous idea. General Relativity says that the metric of space-time can vary. In layman's language this means that it can be stretched.
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Post by striker16 on Jan 15, 2012 17:12:39 GMT 1
Striker16. Observations show redshifts but no actual movement. There are alternative explanations other than recession. This is incorrect. Redshift is a way of measuring an object's recessive speed from an observer based on the wavelengths of light which become stretched the faster away an object is moving. Nobody can define what space is exactly; all that can be done is to measure its effects and base hypotheses on these. Well, if so, such 'impossibilities and absurdities' are the most reasonable hypotheses that meet the observational data. You are making the mistake of assuming space and time existed prior to the BB and therefore imagining one 'point' existing within it. This is not the case. Possibly, but anything beyond what we can presently measure remains speculative and more philosophical than scientific.
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Post by skeptic on Jan 16, 2012 14:48:00 GMT 1
You need to define exactly what space is and prove that photons can be "stretched" by it expanding. It is a rather ridiculous idea. General Relativity says that the metric of space-time can vary. In layman's language this means that it can be stretched. There is no actual evidence for this. It is an idea based on what is needed to make the big bang work. If space is a "material" which can be stretched, you need to explain how it can expand from quantum size to present size without changing in any way. As in something which can drag whole galaxies along with it, it would need substantial solidity of form. As in something that can stretch photons, it would impede their progress to some extent as it would at all levels, even the movement of galaxies through the universe. If space can stretch then surely near massive gravity sources like neutron stars and black holes, they would drag endless space into themselves?
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Post by skeptic on Jan 16, 2012 15:08:39 GMT 1
Striker 16. Gravitational drag causing redshift is indistinguishable from recessional redshift. The universe is full of gravitational sources and like light, gravity is endemic to the universe. How can photons travel anywhere through space without experiencing a drag caused by gravity, and so a redshift? The longer they travel, the more redshift, so it is still a measure of distance.
This is just an idea about space expanding and stretching photons since we have no proof that it can happen or that there are any "effects". A photon cannot be stretched in direction of travel or direction of emission since it moves at light speed and not faster nor slower.
You do not fly off into space because invisible demons are holding you down. They are throughout the universe holding everything together. Proof of their existence is that you do not fly off into space. That is your explanation. There are many serious unanswered questions about the BB which are blandly accepted by virtually all believers as if it were religious dogma. I have pointed them out many times over the years on different science forums and even written to some cosmologists and have yet to receive any credible answers to them.
I am not talking about before the BB but it's moment of happening. It should be a fairly simple matter for a good supercomputer to predict using all known galaxies and clusters and the belief that all are moving away from each other (except where local gravity means otherwise) to reverse time so they all head towards each other so we have a point of origin.
There is no credible origin for how the BB came about.
Parts of the BB might be speculation but many believers look on it as infallible truth.
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Post by striker16 on Jan 16, 2012 18:38:47 GMT 1
skeptic, gravity is simply a label we attach to a phenomenon that can be observed and measured. To go beyond this and obtain a deeper understanding we have to test our hypotheses, which, in the case of gravity means testing for the Higgs boson in the LHC at Cern. Some encouraging results have been forthcoming.
A supercomputer would only be as accurate as the data fed into it, which is always going to be inadequate due to our limited knowledge about how the universe works. Ideas like the BB come about as a result of extrapolations based on the current state of knowledge and we may be in for many surprises in the future.
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Post by skeptic on Jan 17, 2012 14:56:26 GMT 1
Striker16. We would need to get into deep space to test any real hypothesis on gravity. Other than that we can only observe actual motions in space in our solar system.
For actual proof of red shifts, we would need to observe what redshift a distant star has and then observe it over a very long period of time to see if it's real movements correspond 100% to it's red shift.
Even if we prove the Higg's Boson exists, it may just be something that helps hold atoms together and like magnetism, has nothing to do with gravity.
Super computers have been used to model huge events in the universe. If we use single points to represent galaxies, we can run time back, as has been done before in other models. as little as a million scattered galaxies around the universe should tell us if things can be traced back to a single point, and if they cannot, then once again the BB has failed.
The trouble with the BB is that it is not much more than an idea so it should be treated as "the main idea" with other ideas considered. If maybe ten years from now we discover something that in no way can be fitted into the BB, and cannot be ignored then we may have to start from the beginning again as almost all of our eggs are in one basket.
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Post by mak2 on Jan 17, 2012 17:26:39 GMT 1
Yes. That is exactly what does happen.
It is the reason that nothing can get out of a black hole.
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Post by striker16 on Jan 17, 2012 18:22:28 GMT 1
The trouble with the BB is that it is not much more than an idea so it should be treated as "the main idea" with other ideas considered. If maybe ten years from now we discover something that in no way can be fitted into the BB, and cannot be ignored then we may have to start from the beginning again as almost all of our eggs are in one basket. Yes, but the BB idea is the best one that explains the observations. Other ideas have to meet this. Scientists are, in many ways, like a detective because they have to try to figure out what happened to cause the 'crime scene' we observe today, which means examining evidence and allowing for evidence that may yet become available. This is why science does not seek to 'prove' anything but weighs what evidence there is and make hypotheses based on it and then conducts tests to see what happens. Einstein has been tested many times and has been found to be correct but it doesn't mean this will always be the case.
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Post by skeptic on Jan 18, 2012 21:07:05 GMT 1
Yes. That is exactly what does happen. It is the reason that nothing can get out of a black hole. I think the idea is that space is bent in such a way that there is no path out for light. However it is just a matter of the escape velocity being greater than the speed of light.
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Post by skeptic on Jan 18, 2012 21:24:04 GMT 1
Striker16. The big bang starts off with an unproven idea based on an impossibility (singularity), then goes on to an unproven idea (inflation). That is not a credible start.
If we trace expansion back we come to a point where the density of the universe is greater than that needed to make a black hole, and that is a long way from the BB. You have a black hole, you don't have expansion.
OK you can point to redshifts and the CMB but there are alternate explanations for them and as I have pointed out elsewhere, the BB has serious problems with it to the point where I cannot consider it viable.
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Post by eamonnshute on Jan 18, 2012 22:01:11 GMT 1
If we trace expansion back we come to a point where the density of the universe is greater than that needed to make a black hole, and that is a long way from the BB. You have a black hole, you don't have expansion. A black hole can have any density - the mass is proportional to the radius, but the volume is proportional to the cube of the radius, so the greater the mass, the lower the density. You can have a black hole with lower density than the Earth. So you objection is invalid. Also, the early universe had uniform density and infinite size, so the net force of gravity at any point was zero. It could therefore not produce a black hole.
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Post by principled on Jan 19, 2012 12:46:25 GMT 1
Eamonn
Now this is where I get confused. I remember STA saying that the big bang wasn't a point it was everywhere because- I assume- a point is "everywhere" if there is nothing else. However going from this to saying that at the t=0 the universe was infinite in size and yet is still able to expand seems an oxymoron. Can you explain further? P
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Post by eamonnshute on Jan 19, 2012 16:11:29 GMT 1
Now this is where I get confused. I remember STA saying that the big bang wasn't a point it was everywhere because- I assume- a point is "everywhere" if there is nothing else. However going from this to saying that at the t=0 the universe was infinite in size and yet is still able to expand seems an oxymoron. Can you explain further? P This illustrates it:- www.astro.ucla.edu/~wright/infpoint.htmlThe universe is infinite in both pictures, but points within it are further apart in the second one, which is what is meant by expansion in this case.
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Post by mak2 on Jan 19, 2012 17:23:42 GMT 1
You can think of a black hole as dragging space inwards. Once past the point where the speed of drag is greater than the velocity of light, nothing can get out.
There would be a path out, if light could travel fast enough.
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Post by principled on Jan 19, 2012 19:09:53 GMT 1
Mak
This would seem analogous to running the wrong way up an escalator. Run fast enough and you will get back to where you came from, if not you'll go where the escalator takes you! P
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