With the advent of quantum theory over the past 100 years, scientists have been able to develop an elegant mathematical framework capable of uniting three of the four fundamental forces that are thought to exist in the universe. The fourth, gravity, still remains the fly in the ointment, and has resisted unification to this point. Early last year, Dutch theoretical physicist Erik Verlinde published a manuscript to the arXiv that purports to explain why science cannot reconcile all four fundamental forces. According to him, it is simple: "gravity doesn’t exist."
This actually makes an interesting point, sort of. Why don't you recoil when you shine a beam of light? The answer is -You actually do! But not at the same SPEED as the light - with the same MOMENTUM as the light. The momentum (p) of a single photon of light is equal its energy divided by the speed of light (E = c p). So how much momentum does a beam of light carry? Well, suppose we shine a 100 Watt spotlight - we are producing 100 Joules of light energy per second (a Watt is a Joule of energy per second). So every second we are giving that light a momentum of (100J) / (300,000,000m/s) = .00000033 kg m/s.
To give a sense of how hard of a push that is, let's assume that the stupid troll thing in the wagon weighs 50 kg. To accelerate the wagon up to a speed of 1 m/s (around 3 feet per second... which is still pretty slow) would take (33 million * 50) seconds, which is 52 years. And that's assuming no friction!
(In reality, it would never move at all because of friction, so we'd have to do it in space. In fact, even though this seems like a feeble form of propulsion, NASA has plans for prototypes of a "solar sail" to push space probes out of the solar system using no propulsion other than that provided by reflected sunlight!)
A new cosmology successfully explains the accelerating expansion of the universe without the Big Bang Theory's "dark energy":
Time and space are not independent entities but can be converted back and forth between each other. In his formulation of the geometry of spacetime, the speed of light is simply the conversion factor between the two. Similarly, mass and length are interchangeable in a relationship in which the conversion factor depends on both the gravitational constant G and the speed of light, neither of which need be constant.
So as the Universe expands, mass and time are converted to length and space and vice versa as it contracts.
Alternate headline: "Taiwanese physicist's theory threatens much-loved TV show, common understanding of the universe."
What if gravity is an illusion, a sort of cosmic frill, or a side effect of something else going on at deeper levels of reality?
So says Erik Verlinde, 48, a respected string theorist and professor of physics at the University of Amsterdam, whose contention that gravity is indeed an illusion has caused a continuing ruckus among physicists, or at least among those who profess to understand it. Reversing the logic of 300 years of science, he argued in a recent paper, titled “On the Origin of Gravity and the Laws of Newton,” that gravity is a consequence of the venerable laws of thermodynamics, which describe the behavior of heat and gases.
“For me gravity doesn’t exist,” said Dr. Verlinde, who was recently in the United States to explain himself. Not that he can’t fall down, but Dr. Verlinde is among a number of physicists who say that science has been looking at gravity the wrong way and that there is something more basic, from which gravity “emerges,” the way stock markets emerge from the collective behavior of individual investors or that elasticity emerges from the mechanics of atoms.