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Einstein's Biggest Blunder That Wasn't
jose parinas writes "The genius of Albert Einstein, who added a "cosmological constant" to his equation for the expansion of the universe but later retracted it, may be vindicated by new research.
The enigmatic "dark energy" that drives the acceleration of the Universe behaves just like Einstein's famed cosmological constant, according to the Supernova Legacy Survey (SNLS). Their observations reveal that the dark energy behaves like Einstein's cosmological constant to a precision of 10%."
Einstein put in the constant as a fudge because he wanted his equation to match the data. At the time people were not aware of the exanding nature of the universe. I don't think he ever liked using the constant, and was relieved when it turned out it wasn't necessary. Everything was neat again.
That's my take on modern cosmology. That there exists this one substance, the vacum substance, the stubstance of space-time itself. It can be imagined as a drop of water, or equally as a cloud of moisture. It contains volumes within it that are "denser" than other volumes. We say that there is "more space" (or less?) within those volumes. All "material" goods are then just some kind of configuration of this "space-time" stuff. I think also that based on quantum mechanics, and the "Beckenstein bound", material within a given volume can be realized in much the same way pictures are made up of "pixels" on a computer screen. Think of it. Your computer screen resolution determines all objects that are "realizable" within its resolution. The Beckenstein bound then formulates a given volume for space-time in which objects of a given size can fit. The relationship of the "density" of space-time then should directly influence the Beckenstein bound such that, if there is "more space", then there should be the possibility of a larger number of possible quantum states within the abstract volume of space-time.
If you had a glass sphere the size of a basketball, what are all the material objects that are realizable within that space? Well, we can put car keys, pens, small animals/insects, etc. But we cannot put a house inside a basketball right? Well maybe a doll house. But how would we go about putting a real house in a volume the size of a basketball? Simple, just increase the density of space-time within that abstract volume. That will increase the number of quantum states possible just like increasing the resolution of your computer screen. But what do we mean when we say "space is dense"? Since the vacum is matters "opposite", we would probably conclude that space would be "denser" where matter is not. So we might say that within a "black-hole" there is theoretically "no space". A black hole would then indeed be a hold within space-time, a tear in the fabric of reality for example. But this may not be the case. It could be that a black hole is a place were the density of space is so high as to be exactly "solid" space-time. In this respect matter flows into a black hole and then becomes converted to "space-time", which then slowly and inexorably flows outward. Space-time is being generated by a black-hole by the conversion of matter to space-time.
If space-time is a substance of some kind, and all matter is just some configuration of it, then that would explain why we cannot move faster than light. This would be the case if we were somehow made of configurations and vortices of "air". Since we being made of "air", we could not move faster than sound right? Of course doesn't the speed of sound vary with the density of air? Would not the speed of light vary with the density of space-time? Of course it does, this was Einsteins great find, that light travels along a space-time geodesic. The geodesic caused by the "density" of space-time.
Based on all these analogies, I don't see why we have to think about the fourth dimension at all. We just need to imagine space-time as a volume with varying densities. Within a high density of space-time, you can have more matter, and more quantum states. It is abstract I know, but for my mind it works. Is there a reason that these analogies can be viewed as "wrong"? I'm willing to take an alternate view.
I get tired of this description of the Big Bang as an explosion in the usual terms, as in things flying apart out into something, "matter flying off in all directions". It's popular science, and most people wouldn't know what the heck you were talking about if you described it any other way. But, it ought to be restated...
It's an expansion of space, everything that is in space is just going along for the ride.
A visual way to clarify that is to shoot down the idea people have that things cannot recede faster than light. That gets their attention, they all know about Einstein and c. Things cannot move through space faster than light, but space itself puts a distance between things that C can never outpace.
Not a stupid question at all.
It is possible to have the universe expand and contract in different directions at the same time. However, this isn't what we observe. Two of the basic ideas about the universe we assume to be broadly true (yes, not exactly but to a good approximation) are
1) It is homogeneous. This is math speak for it's the same at every point
2) It is isotropic. Math speak for looks the same in every direction.
Now, this clearly isn't exactly true - if it were there would be no difference between the earth and an empty vacuum of the same size. However, on a very very large scale (where galaxies appear like point particles because they are so small) this appears to be true. We get this from the Cosmic Microwave Background - a set of rays that fly towards us from all around the universe in a fairly uniform manner. Also when you look at the "Redshift" of galaxies (like the doppler shift of sound makes a siren sound higher when an ambulance approaches and lower when it moves away) it looks like all galaxies are moving apart from one another in equivalent directions. So we guess that the universe is largely isotropic and homogeneous, make a broad model and then do corrections (perturbations about the solutions to the equations) for the bits that aren't.
So given the idea that it's isotropic and homogeneous we get that it must expand at the same rate in all directions etc. However, there's nothing in the everyday physics to say that it necessarily is - just the observations of some cosmic phenomena.
The asteroids thing is kind of a side point - that's more to do with the topology of the universe. Asteroids is like a torus (or donut with a hole) shape - you go one way for a while you end up back where you started. Some models of the universe have the universe be a 3-torus (an extension of the donut in another dimension, cue Homer drool). However, the universe is broadly thought to be either flat (just like regular space looks) a 3-sphere (like a ball but with another dimension again) or a hyperboloid (hard to explain, but like the inverse of the sphere). This all depends on the matter in the universe and the cosmological constant in a fairly complex way.
Although if you mean that the universe could cycle, that again is possible - it could expand, contract, expand again indefinitely. If you look at the works of Bojowald, for example, on Loop Quantum Gravity he seems to think that the big bang could be just part of a cycle of expansion and contraction.