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Physicist Create a Fluid With Negative Mass

Physicists from Washington State university have created a liquid with negative mass meaning that when you push it, instead of accelerating in that direction, it accelerates backwards.

Matter can have a negative mass much the same way that particles can be negatively charged. Newton’s second law of motion (F=ma) tells us that mass will accelerate in the direction of the force so we can deduce that matter with a negative mass would do the opposite and accelerate against the force.

To create the conditions for negative mass, Peter Engels and his team started by cooling rubidium atoms to a Bose-Einstein condensate meaning they reached very near absolute 0. The researchers used lasers to trap the atoms in an area less than 100 microns across and allow high energy particles to escape cooling them further. Then to create negative mass, the physicists applied a second set of lasers to change the way atoms spin back and forth. They then removed the first set of lasers causing the rubidium to rush out and appear to hit some sort of invisible wall; behaving as if it had a negative mass.

What’s great about this is the control we have over the negative mass without any other complications. This gives us a new tool we can use to engineer experiments in astrophysics looking at neutron stars, black holes, dark energy and a lot more.

This is an inaccurate explanation. I saw this research presented at the aps northwest conference and they were very clear that it is a negative effective mass. Scientists use words carefully for a reason. It accelerated in the opposite direction due to a dispersion relationship NOT because they “created negative mass.”

You almost do a decent job representing this when you say “behaving as if it had negative mass.” Unfortunately your title and every other time you mention the effective negative mass you do not make that clear. I actually think the paper itself doesn’t do a great job of making this important distinction clear either. But they do properly refer to it as effective mass which people in the field would understand doesn’t mean “negative mass” in the way you imply.

It is still interesting and exciting research that we should talk about. The way you handle communicating it though is misleading. It is important that we communicate science accurately and with the nuance it deserves. Instead you continued making the same mistakes science journalism usually falls prey to.

Here is a link to the paper that people who don’t have an APS subscription can actually access and a link to the Wikipedia page for effective mass.

The paper

Effective mass