It’s Official: NASA’s Peer-Reviewed EM Drive Paper Has Finally Been Published

Science Alert has published these interesting news: It’s Official: NASA’s Peer-Reviewed EM Drive Paper Has Finally Been Published.

In case you’ve missed the hype, the EM Drive, or Electromagnetic Drive, is a propulsion system first proposed by British inventor Roger Shawyer back in 1999.

Instead of using heavy, inefficient rocket fuel, it bounces microwaves back and forth inside a cone-shaped metal cavity to generate thrust.

According to Shawyer’s calculations, the EM Drive could be so efficient that it could power us to Mars in just 70 days.

But, there’s a not-small problem with the system. It defies Newton’s third law, which states that everything must have an equal and opposite reaction.

According to the law, for a system to produce thrust, it has to push something out the other way. The EM Drive doesn’t do this.

This is a good reminder that we are far from knowing everything and there are inventions to be made, laws of nature discovered, and knowledge acquired.  Exciting!

Inside an atom

Imagine a chamber.  Now flip on the switch that creates a strong electrical field inside that chamber.  Now imagine not one, but two laser guns mounted inside that chamber.  Flip the switch that activates both of these guns and their targeting system.  It does sound a bit scary already, doesn’t?  Well, all we need know is a target.  Imagine that.  A moving one, inside the chamber. BZZZT!  Laser guns zap the target, which now rips apart and hangs in the middle of the air, because of the magnetic forces of the electrical field.  Snap the picture!


Cool, isn’t it?  Well, now do a bit of scaling.  The target that you just zapped in the chamber is the size of the hydrogen atom.  It’s not tiny.  It’s beyond tiny.  You probably will need an industrial size telescope to even see the chamber!  Slashdot points to the story that covers the experiment.

But, maybe, I’m just way out of sync.  According to one of the Slashdot comments, it’s not as exciting as I picture it:

Now this would have been a fundamental breakthrough if it would have been done many decades ago. These days, we have extremely high confidence in our theoretical/computational models of the wavefunction of atoms and molecules. “Just as valuable for developing quantum intuition in the next generation of physicists?” Naah, this stuff has been well-known since before most of us were born.
Don’t get me wrong, I don’t mean to belittle this accomplishment – it’s all kinds of cool that they pulled off this experiment in the first place, and notwithstanding the huge body of other experimental evidence, it’s a beautiful direct confirmation of longstanding quantum mechanics theory. And as mentioned in TFA, provided they can scale this up to larger and less well-understood systems than the hydrogen atom, it might make it possible to obtain unique data on nontrivial materials like molecular wires. The only problem I have is that the Science editor is overselling it a bit; at the end of the day, it’s not going to change our quantum mechanical worldview the slightest.

Guinness bubbles problem – solved!

If you are a beer fan, you’ve probably heard about the famous Guinness bubbles problem.  While bubbles in most other beers rise up, in Guinness they go down.  A lot of people were puzzled by that fact, and now, it seems, the puzzle is solved.

According to the article in Technology Reviews, Irish mathematicians came up with an answer:

Today, a dedicated team of Irish mathematicians reveal the answer. Eugene Benilov, Cathal Cummins and William Lee at the University of Limerick say the final piece in this puzzle is the shape of the glass, which has a crucial influence over the circulatory patterns in the liquid.

To understand how, first remember that the motion of every bubble exerts a drag on the liquid around it. Now imagine what would happen if there were a region of liquid containing fewer bubbles near the wall of a pint glass and consequently a region of higher bubble density near the middle of the glass.

Benilov and co say that the drag will be higher in the region where the bubble density is higher, in other words near the centre of the glass. This creates an imbalance that sets up a circulation pattern in which the liquid flows upwards in the centre of the glass and downwards near the walls.

That’s exactly as observed in a pint of Guinness.

There are more details and image of an anti-pint in the article.  Read it.

Also, while reading up on the subject, I’ve learned something else about Guinness – the widget.

Atomic physics resources

Doing my duty in promotion of knowledge and science, I bring you this collection of resources on atomic physics.  With the way the world goes, who knows when you’d need a quick reference to some research.  And, in case you are a bit rusty on what atomic physics is, here is a quick quote for you from the Wikipedia.

Atomic physics (or atom physics) is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and the processes by which these arrangements change. This includes ions as well as neutral atoms


The term atomic physics is often associated with nuclear power and nuclear bombs, due to the synonymous use of atomic and nuclear in standard English. However, physicists distinguish between atomic physics — which deals with the atom as a system consisting of a nucleus and electrons — and nuclear physics, which considers atomic nuclei alone.

As with many scientific fields, strict delineation can be highly contrived and atomic physics is often considered in the wider context of atomic, molecular, and optical physics. Physics research groups are usually so classified.