In the physics community, there is no more broadly respected figure than Albert Einstein. Einstein is a transformative figure in the history of physics, comparable only to Isaac Newton in the sheer breadth of how he changed our way of thinking about the physical world. The key insight for which he is credited is his development of the theory of relativity, which allowed physicists to understand the behavior of physical objects in terms of the geometry of the spacetime that they inhabited.

Physics is a progressive discipline, however, and physicists are continually probing the limits of the known in order to expose what is not known. As such, many physics students over the last century have dreamed of finding the next major discovery that would transform physics, making their own contribution to human knowledge and becoming as equally respected.

And, of course, the media would love to report on such a transformation! As such, every so often there comes along a big media flurry around a piece of evidence or new theory that claims to "overthrow Einstein." Usually, I ignore such media hype, because it so far has never panned out.

The last big "Einstein was wrong" news story related to the 2011 announcement that there might have been evidence of neutrinos traveling faster than the speed of light. That turned out not to be the case, despite excitement over reporting what was potentially a revolutionary story. Still, it's useful to occasionally address these things as they happening, if only to understand the way that science works. (See, for example, our article: "Can Anything Move Faster Than the Speed of Light?")

Geometric Unity

The most recent of these seems to be in the works as I type this. I learned about it through an article in Britain's The Guardian, and then read this other Guardian blog post and it was also mentioned on Peter Woit's Not Even Wrong blog.

The fuss is about a guy named Eric Weinstein, who left academia twenty years ago to become a New York economist. In that time, however, he's apparently been peripherally working on mathematics related to solutions to fundamental problems in physics. He is at Oxford today giving a talk about his new theory, which he's calling Geometric Unity.

The problem that Weinstein is trying to tackle is not a new one. It's the well-worn idea that quantum physics and general relativity are exceptional theories for explaining their own domains, but in the cases where they intersect (such as the big bang and black holes), physicists have trouble getting the two theories to work together in a way that really makes sense of the situation, at least without cheating a little bit on one or both of the theories. This has resulted in searches for a theory of quantum gravity, such as the one that Einstein unsuccessfully devoted the latter half of his life to.

Weinstein's approach is to embrace Einstein's intuitions, as evidenced in this tweet (@EricRWeinstein) that Weinstein made yesterday:

Perhaps no university in the world has done more than Oxford both for, and to keep faith with, Einstein's vision for physics as geometry.

Though there are only a couple of reports so fall, and I expect more detail following Weinstein's speech, but so far it seems that the theory involves a 14-dimensional geometry that contains new symmetries above and beyond those already present within the Standard Model of physics. There is some speculation that this might explain current mysteries within physics, such as the problem of dark energy in cosmology.

How Would We Know?

These are the sort of claims that must be treated with a high degree of skepticism. In 2007, physicist and surfer Garrett Lisi made a splash (figuratively, that is, since this was in physics rather than surfing) by putting forth an idea about how to unify physics. Ultimately, though, Lisi's approach was abandoned not because physicists didn't like it, but because it did not make sufficient testable predictions. No matter how great a scientific theory is, if the theory does not make predictions that can come up against analysis in physical reality, it can't go anywhere. Elegance for its own sake is not enough.

Weinstein's ideas will be put forth in front of the world today in his Oxford speech. At that point, physicists will begin looking it over, considering the implications of the theory from a variety of angles. The big tests will come in the following forms:

1. Does it contradict known evidence?
2. Does it explain existing evidence that cannot be explained under current theories and models?
3. Does it make a prediction about new evidence that scientists can search for?

Answers of "No" to the first question and "Yes" to the second two questions are good for the new idea.

And that is how a hypothesis becomes a theory! (Cue Schoolhouse Rock theme song.)

Update: This morning, I stumbled upon this New Scientist article, "Weinstein's theory of everything is probably nothing," which makes things even more interesting ... apparently, Weinstein's Oxford lecture was scheduled at a time when the majority of the Oxford physics department was busy listening to another lecture! As I mentioned above, any internal mathematical elegance that Weinstein's theory may possess is secondary to its ability to actually demonstrate physics results ... which means that physicists have to be centrally involved in the discussion!

I came across this intriguing video of a banana being levitated in the air. This isn't the first time I've discussed this strange new technology of quantum levitation, but it's been a while. The last time I brought it up was back in November 2011, when talk show host and comedian Stephen Colbert levitated his ice cream flavor on his show.

These are hardly the most serious examples of how this technology could be used, but they are very cool ... reminding us that scientific discoveries are often leveraged in unexpected (and entertaining) ways. But if you look under the banana (so to speak), you'll find some very deep understanding of the science matter and electromagnetism:

• What is Quantum Levitation (and How Does It Work)?
• Quantum Locking
• The Meissner Effect

Image Source: Tel Aviv University

Physicists like it when things crash together. Okay, not so much when they do so unexpectedly. Just like anyone else, physicists prefer to keep their cars out of the body shop.

But collisions of objects do provide excellent opportunities to use the tools of physics to pull out some of the oldest, most trusted tools in the physics toolbox.

The key to any sort of collision is that it follows the law of conservation of momentum. In most collisions, however, there is a loss of kinetic energy. These collisions are called inelastic collisions, and in the real world this represents most of the types of collisions that we run into. In some collisions, in fact, the objects collide and stick together, losing the maximum amount of kinetic energy possible. These are called perfectly inelastic collisions.

Some collisions, on the other hand, do not lose kinetic energy during the collision ... or, at least, they lose so little kinetic energy that we can treat them as if they didn't lose any. (Recall that in physics we often try to approximate systems with an idealized model if at all possible.) These types of collisions are called elastic collisions, and they are decent first-order approximations for Newton's cradles (as depicted above), billiard balls banging into each other, or bumper cars.

If a collision generates a lot of heat and sound, chances are that it is an inelastic collision, since the original kinetic energy is getting transformed into the vibrating molecules that make up the heat and sound. If you could measure each and every vibration caused by the collision and calculate the total energy, it would of course equal the total energy before the collision. But this is impractical and, fortunately, unnecessary, since conservation of momentum typically gives us a sufficient set of tools to understand what happens in the collision.

When you're dealing with a homework problem that has to do with two objects colliding, a good question to ask oneself is: What type of collision is this? That'll help set you on the road to figuring out which equations you can apply to the situation and how to solve the problem.

Image Source: Tyler Boley/Getty Images

One of the deepest questions in physics is the attempt to provide an answer to the seemingly simple questions: Does time really exist?

Though we all experience time moving in one direction (the "arrow of time" as it is called), the curious thing about the laws of physics don't actually require this. If you tried to apply the equations with time moving the opposite direction, they would actually still make sense. Why, then, do we experience such an unrelenting forward motion in time?

The standard explanation revolves around the concept of entropy. As well explained in Sean Carroll's 2010 book From Eternity to Here: The Quest for the Ultimate Theory of Time, the solution that is most commonly accepted these days is that the arrow of time is an artifact of the initial conditions of the universe. Because the early universe was highly ordered, time moves in the direction of increasing entropy.

This answer doesn't cut it for controversial theoretical physicist Lee Smolin. In the new book Time Reborn: From the Crisis in Physics to the Future of the Universe, Smolin confronts the idea that time is "unreal" and argues instead for treating time as a fundamentally real quantity. His conclusion is that our entire approach to theoretical physics may need to be rethought. Instead of looking for eternal and timeless laws of physics, Smolin believes that we should instead look for laws of physics that themselves evolve throughout time.

It's an intriguing proposal and, if adopted, would certainly revolutionize the approach to physics. This is nothing new to Smolin, who is nothing if not an unconventional thinker. I go into some of the reasoning behind Smolin's approach in the review of the book.

What do you think? Is time real? Does physics adequately address questions about the nature of time?