Posted on 01/20/2015 4:43:30 PM PST by LibWhacker
Some simple observations about the universe seem to contradict basic physics. Solving these paradoxes could change the way we think about the cosmos
Revolutions in science often come from the study of seemingly unresolvable paradoxes. An intense focus on these paradoxes, and their eventual resolution, is a process that has leads to many important breakthroughs.
So an interesting exercise is to list the paradoxes associated with current ideas in science. It’s just possible that these paradoxes will lead to the next generation of ideas about the universe.
Today, Yurij Baryshev at St Petersburg State University in Russia does just this with modern cosmology. The result is a list of paradoxes associated with well-established ideas and observations about the structure and origin of the universe.
Perhaps the most dramatic, and potentially most important, of these paradoxes comes from the idea that the universe is expanding, one of the great successes of modern cosmology. It is based on a number of different observations.
The first is that other galaxies are all moving away from us. The evidence for this is that light from these galaxies is red-shifted. And the greater the distance, the bigger this red-shift.
Astrophysicists interpret this as evidence that more distant galaxies are travelling away from us more quickly. Indeed, the most recent evidence is that the expansion is accelerating.
What’s curious about this expansion is that space, and the vacuum associated with it, must somehow be created in this process. And yet how this can occur is not at all clear. “The creation of space is a new cosmological phenomenon, which has not been tested yet in physical laboratory,” says Baryshev.
What’s more, there is an energy associated with any given volume of the universe. If that volume increases, the inescapable conclusion is that this energy must increase as well. And yet physicists generally think that energy creation is forbidden.
Baryshev quotes the British cosmologist, Ted Harrison, on this topic: “The conclusion, whether we like it or not, is obvious: energy in the universe is not conserved,” says Harrison.
This is a problem that cosmologists are well aware of. And yet ask them about it and they shuffle their feet and stare at the ground. Clearly, any theorist who can solve this paradox will have a bright future in cosmology.
The nature of the energy associated with the vacuum is another puzzle. This is variously called the zero point energy or the energy of the Planck vacuum and quantum physicists have spent some time attempting to calculate it.
These calculations suggest that the energy density of the vacuum is huge, of the order of 10^94 g/cm^3. This energy, being equivalent to mass, ought to have a gravitational effect on the universe.
Cosmologists have looked for this gravitational effect and calculated its value from their observations (they call it the cosmological constant). These calculations suggest that the energy density of the vacuum is about 10^-29 g/cm3.
Those numbers are difficult to reconcile. Indeed, they differ by 120 orders of magnitude. How and why this discrepancy arises is not known and is the cause of much bemused embarrassment among cosmologists.
Then there is the cosmological red-shift itself, which is another mystery. Physicists often talk about the red-shift as a kind of Doppler effect, like the change in frequency of a police siren as it passes by.
The Doppler effect arises from the relative movement of different objects. But the cosmological red-shift is different because galaxies are stationary in space. Instead, it is space itself that cosmologists think is expanding.
The mathematics that describes these effects is correspondingly different as well, not least because any relative velocity must always be less than the speed of light in conventional physics. And yet the velocity of expanding space can take any value.
Interestingly, the nature of the cosmological red-shift leads to the possibility of observational tests in the next few years. One interesting idea is that the red-shifts of distant objects must increase as they get further away. For a distant quasar, this change may be as much as one centimetre per second per year, something that may be observable with the next generation of extremely large telescopes.
One final paradox is also worth mentioning. This comes from one of the fundamental assumptions behind Einstein’s theory of general relativity—that if you look at the universe on a large enough scale, it must be the same in all directions.
It seems clear that this assumption of homogeneity does not hold on the local scale. Our galaxy is part of a cluster known as the Local Group which is itself part of a bigger supercluster.
This suggests a kind of fractal structure to the universe. In other words, the universe is made up of clusters regardless of the scale at which you look at it.
The problem with this is that it contradicts one of the basic ideas of modern cosmology—the Hubble law. This is the observation that the cosmological red-shift of an object is linearly proportional to its distance from Earth.
It is so profoundly embedded in modern cosmology that most currently accepted theories of universal expansion depend on its linear nature. That’s all okay if the universe is homogeneous (and therefore linear) on the largest scales.
But the evidence is paradoxical. Astrophysicists have measured the linear nature of the Hubble law at distances of a few hundred megaparsecs. And yet the clusters visible on those scales indicate the universe is not homogeneous on the scales.
And so the argument that the Hubble law’s linearity is a result of the homogeneity of the universe (or vice versa) does not stand up to scrutiny. Once again this is an embarrassing failure for modern cosmology.
It is sometimes tempting to think that astrophysicists have cosmology more or less sewn up, that the Big Bang model, and all that it implies, accounts for everything we see in the cosmos.
Not even close. Cosmologists may have successfully papered over the cracks in their theories in a way that keeps scientists happy for the time being. This sense of success is surely an illusion.
And that is how it should be. If scientists really think they are coming close to a final and complete description of reality, then a simple list of paradoxes can do a remarkable job of putting feet firmly back on the ground.
If so and if one could navigate space fast enough and head "outward" would there be an end of the "matter" infested universe in a sense that looking outward there would be nothing to see but darkness?
What exactly is an "Event Horizon"? I once saw a movie of that name but could never understand the term........
How long did it take you to type that?
The point in the mouth of a Black hole where the gravity is so strong light cannot escape.
Hence you see nowt but black.
As far as i know ,only X-rays are emitted back from the Event Horizon.
(Last line.) LOL+!
20, 30 minutes. I’m a software developer now, so I pretty much type for a living.
X-Rays: Nothing comes back from the event horizon [well, because of Quantum Mechanics that's not quite true, but close enough.]
The X-rays "emitted from" Black Holes are actually the result of gravitational effects happening within a few thousands or millions of miles outside the event horizon. Here is one explanation: http://physics.stackexchange.com/questions/24958/how-can-a-black-hole-emit-x-rays. There are other reasons as well. But all of them are well beyond the event horizon.
I hope you didn't take my question in the wrong way, I'm absolutely enthralled with your explanations on things that I used to dream about knowing...........thanks.
Not at all. I assumed it was just a point of curiosity.
if one could navigate space fast enough and head "outward" would there be an end of the "matter" infested universe in a sense that looking outward there would be nothing to see but darkness?
In essence, is there an outlying edge of the existing universe where beyond that point lies nothingness? Or, is the existing universe contained within a box where there is ultimately a wall at the end of the expansion?
After looking at it, I know, it's a stupid question The question is not meant in any manner of "gotcha" but rather a combination of astrophysical and religious curiosity.......Thank you
imagine that. seems like just yesterday that “string deniers” were *this close* to being burned at the stake.
Okay, got it — thanks.
Including some VERY BIG ideas that we don’t yet have.
.................
The 1890’s were about 10-20 years before Einstein’s work. It seems to me I’ve read articles that suggested that scientists of the day were seeing too many things that didn’t fit the then standard model. So they thought a paradigms shift was just over the horizon. And so it was.
Do you see a paradigm shift coming in the nest 10—20 years.
An outstanding and delightful read. Well done and much appreciated. Thanks.
In doing so, they created a problem, because you see, it was known that there was an enormous disconnect between the known properties of the electromagnetic force, and Newton's Laws of classical physics.
The problem, in a nutshell, is that Maxwell's equations were already Lorentz Invariant: they already obeyed the Special Theory of Relativity ... 41 years before Einstein!
And so it was known we needed to reconcile these two things because both appeared to work in the cases where you could keep them separate. That is very much analogous to what we have today, where you have this tremendously successful theory of Quantum Mechanics/Quantum Field Theory on one hand and General Relativity on the other. And, as was the case before, they can't both be correct [and it's pretty clear that it's General Relativity that has to be wrong.]
The difference now, unlike then, is that in the late 19th and early 20th century people were doing all kinds of cool things with electronics, electromagnets, motors, generators, radio waves, ... probing deeper and deeper. We can't to that now, because the energies we can reach in our accelerators are many orders of magnitude too small for us to really investigate things. We have the theories, but we don't have the experiments. [It took us a really long time to reach the energies we needed to find the Higgs, for example. The next levels we need to reach are so much higher.]
Now, there is some hope, and that hope is in space. Because the energies we need to reach that we can't reach in our labs existed once: in the 10-30 or so seconds right after the instant of creation.
So it may be possible that we can reason some of things these backwards from what we see in the sky. Not just reasoning from cosmology, but also in the so called "cosmic rays" which bombard the top of our atmosphere. These are really tremendously energetic γ rays [some are powerful enough to spawn particles in the range to test some theories that we can't test on earth.]
But it's going -- just in my opinion -- to take a lot of work, and I don't think that 10-20 years is enough.
The best way too think of this is the balloon analogy. The dots on the balloon are, say, galaxies or galactic clusters. As the balloon inflates, they are moving away from each other on the surface.
Now, this is a three dimensional model of our four dimensional world, so we have had cut out one of the dimensions. People living on the surface of the balloon can only move in two spatial dimensions instead of three. They are constrained only to have [as we have on the surface of the earth roughly] only two degrees of freedom: the polar and azimuthal angles θ and φ of spherical coordinates, or, what is more familiar to laymen, latitude and longitude. The third dimension on this balloon, the distance from the center of the balloon, is time.
This is a very old analogy. There is a story about Einstein that goes with it.
When Einstein escaped from the Nazis, he worked at the center for advanced studies in Princeton, New Jersey, and he used to go for walks to think his deep thoughts. In the course of those walks he had a favorite little ice cream shop he used to go into, and the store owner had heard about the analogy of the balloon, and he asked Einstein essentially the question that you're asking: "What's outside of the sphere of our universe?"
Reportedly, Einstein took a couple of licks of the ice cream, thought for a moment, and then said, in his heavy German accent, "Yah... Vell... chust don't chew go out dere."
Now, think about what is inside of the balloon, and it will tell you what is outside of the balloon. And it will also tell you what is on the outside of the four dimensional balloon of our universe.
I'll post the answer tomorrow. [But better: you post the answer to me first.]
Well, about the only answer I can come up with is that the universe is expanding outward as a result of the "bang" and the space between the point where the bang occurred and where the matter now sits, is just empty space like the inside of the balloon.
As far as the expanding balloon we are on, there is nothing beyond it but dark, empty space.........
My burns have just about healed. ;’)
[and it’s pretty clear that it’s General Relativity that has to be wrong.]
...............
Does this mean that its more or less likely that science fiction things like worm holes and warp drives are possible.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.