Time?

TimeLord,

If photons exist in all of space at once, why does it take time for a photon to go from one point to another?
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While photons appear to be free of the constraints of special relativity (from our perspective) we aren't. We aren't traveling at the speed of light. From our timelike space photons take a finite amount of time to go from point A to point B. If we could somehow manage to travel at the speed of light we would see the world in the same manner as a photon sees it. Ignoring all of the other physical laws that we would run up against, if we travel at the speed of light we too would see the world folded up into a point. Light speed navigation would be a bit of a problem for us if the entire universe was simply a point.

I should add that the world may not actually be as I've described it. What the world is "really" like under the most extreme conditions such as the speed of light and/or virtually infinitely strong gravitational fields is still among the unanswered questions of quantum physics and special/general relativity. But based on what we do know about QM and SR/GR that's the picture that emerges. Right now those two classes of physics are so thoroughly verified that we believe that they are correct to the known limits of their applicability. The unanswered questions are why and how. Why is the world the way that they describe it and how does it happen (what are the underlying mechanisms). We really don't know. String theory is attempting to answer the questions but string theory has been almost dead in the water for 30+ years. So far string theory hasn't even been able to postulate an experiment to verify itself. Where The Standard Model of particle physics has about 15 somewhat ad hoc variables string theory has had to insert 105 ad hoc variables including 7, 8, 10, 11 and 26 new spatial dimensions. These spatial dimensions are not derived from the theory. They are added to the theory to make certain parts of it "work out". String theory isn't even a theory. It's actually five theories all of which postulate something on the order of 10^100 (or in some cases 10^1500) "worlds". That makes it a bit hard to pick out our world from the landscape in order to experimentally test the theory.
 
TimeLord,

It seems to me that Einstein's religion caused him to try to reconcile physics with the torah ("Let there be light" = "big bang"). It just seems forced. Did I miss something?
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You did miss a couple of things. Einstein wasn't the originator of the speed of light maxima. It had been postulated long before his time. The question that he pondered had to do with Maxwell's inquiries into electromagnetism in the 1860's. Maxwell had noted the apparent paradox and it appears in his equations. Lorentz had already published his transformations in the late 1800's in an attempt to solve Maxwell's mystery. Einstein's genius was to toss out the ideas of the ether, absolute time and absolute space, set the issue down in the form of differential equations and let the math derive the theory. It worked out as envisioned. The either, absolute time & space were shown by the math not to be necessary to explain the observations. Experiments have shown the math to be the correct description of reality (again, to the limits of the domain of applicability).

Einstein didn't postulate the Big Bang. The Big Bang theory was offered by Georges Lemaître (Belgium), Alexander Friedmann (Russia) and Edwin Hubble (USA) over a period of several years in the 1920's and 1930's. Einstein had some definite ideas about cosmology but he was a theoretical physicist, not a cosmologist or astronomer. But the theory was derived from the implications of general realtivity.
 
As you can see, I'm no expert on the history of science. :oops: Thanks again for taking time to explain things. I'm sure I'll have more to ask later.
 
TimeLord,

As you can see, I'm no expert on the history of science. Thanks again for taking time to explain things. I'm sure I'll have more to ask later.
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You're welcome.

You bring up the Big Bang theory at a good time in the discussion. It's a good theory but it does have problems - problems that are known and acknowledged by cosmologists and astronomers. It's the CMBR (cosmic microwave background radiation).

In thermodynamics we have a pretty clear idea about how the 2nd Law works and how entropy is related to it. If you'll excuse a rather incomplete definition, entropy is a measure of order (or disorder). High entropy is disorder. Low entropy is order. Order/disorder have particular meanings in this case. Disorder tends to mean a lack of differentiation - everything is smooth and looks the same in every direction. Think of a closed box where all gas has been evacuated. It's a vacuum inside. In one corner there's an area walled off from the rest of the box by a sliding door. Inside the small area is a gas. Taken as a complete system (the box and small area in the corner) entropy is low and orderliness is high. You can differentiate the corner from the rest of the interior of the box. Now slide the door away and let the gas diffuse throughout the interior. After some time the gas is in a state of thermal equilibrium. The gas has completely diffused and on the whole the density in one part of the interior is the same as any other part of the interior. You can't look at the gas and differentiate one area from another. That's high entropy and low order. If you keep the system closed (don't allow anything to escape from or enter into the box) you would expect that no matter when you look at the gas once thermal equilibtium is reached that it will continue to look the same.

There's a definite time component in play. We rationally expect and experimentally verify that the ordered state came before the disordered state. The chance that the time order of the events was that the gas randomly migrated from the thermal equilibrium state to the one corner is vitrually zero, but not exactly zero. It could happen but it's not a bet that you'd want to make no matter what odds were given. You might win on the first bet, it's possible. But you might want to plan in rebetting for several billion years to have some chance of winning one bet.

If we take that little experiment and say that we can use entropy as a clock we can apply it to cosmology. And sure enough, when we look out into the cosmos the universe looks pretty much the same in every direction. Hubble proved that it is also expanding. The universe is old. When we apply general relativity and run the clock backwards we see the universe contracting and order increasing implying that sometime 13 to 20 billion years ago the universe was a singularity. But there's that danged CMBR. We surmise from its very consistent temperature of ~2.7 Kelvin (+2.7 degrees above absolute zero) that it was created at about the time of the Big Bang. The problem is that it is very fine grained. It is very uniform in every direction. It has extremely high entropy - low order - but it comes from the era of low entropy - high order. That shouldn't be if the Big Bang theory is correct and the 2nd Law of thermodynamics is correct.

So we have a conflicting data and need some creative thinking to explain it.
 
Definitely a lot of conflicting theorys on this subject , I guess the biggest one is the age of the universe itself which, According to theory, Is 13.7 billion years, But this is only based on the red shift and from nasa's all sky picture and Hubble's deep space photos which are limited by the barrier of light speed. Most scientists will agree that there is no reason to believe that our cosmological horizon is the end of the universe, so why put an age on it? One theory states that space is expanding faster than the speed of light so anything outside our own light horizon we will never see because the space in between is expanding faster than the light can reach us, However, Another theory sais that an observer on the edge of our horizon would have a light horizon of there own which would span another 6 or 7 billion years past our horizon and that this process could go on infinitely, So how does the C.M.B.R. come into play in all of this? How is it that we are surrounded, Same distance in all directions, By the very first light rays in time?
 
There was the background radiation found by Bell Labs back in 1965 or so. The thought out temperature that exist there something like 2.7 degrees Kelvin above absolute zero, the ends of the Universe in all directions discussed before by Wilson and Pe ings (I have to look up the names.)
 
So how does the C.M.B.R. come into play in all of this? How is it that we are surrounded, Same distance in all directions, By the very first light rays in time?
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The CMBR dates back to shortly after the Big Bang - about year +300,000. The current theory seems to be that it is no longer though to be the "echo" of the Big Bang but the echo of symmetry breaking...when the universal temperature cooled enough so that the elemenary forces were no longer unified.

Aging the universe requires that a lot of physical evidence be processed and several assumptions have to be made. We obviously weren't there to witness it and the evidence that he have is over 13 billion years old. At this point it is probably somewhat useless to try to refine the age estimate too much because we really need to solve the problem of quantum gravity first. The more that we know about gravity at its deepest levels the more accurate our cosmology theories of the very early universe will be.
 
Blair,

I don't believe that "anything" is possible now that the LHC is up and running. The only real advantage for the LHC is that we can have particle "collisions" of a certain energy level in a controlled environment. But the LHC is still doing experiments that are 100+ times less, energywise, than what we have already detected in cosmic ray collisions in the atmosphere. We'll answer a lot of quesitions but we won't be able to recreate the most energetic cosmic ray collisions.
 
"Time will tell"

Nice reply. Simple, direct and not requiring of any deep thought process. Superficial. TIme will tell, indeed.
 
It's ok im the same when i get up in the morning and havent had my coffee yet.
Darby not mean he just hates that i dont post a novel when i respond and wants to know what im thinking about all this time travel stuff.
 
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