Monday, November 28, 2016

An exotic space propulsion system

I have not blogged about the EmDrive before although I have followed it for years. It seems far-out - a space propulsion system which is propellantless. It seems to violate the law of momentum. Many still regard it as impossible and there is no generally accepted explanation of how it works. However careful tests, some by NASA, have found that it does seem to produce a small steady thrust.

Remember that effects have many times been pronounced impossible before but later accepted. I am posting an item about the EmDrive as an example of such.

NASA is publishing a paper describing tests they have been conducting, as reported by NextBigFuture.

An article in DigitalTrends gives an overview:
"The issue is, the entire concept of a reactionless drive is inconsistent with Newton’s conservation of momentum, which states that within a closed system, linear and angular momentum remain constant regardless of any changes that take place within said system. More plainly: Unless an outside force is applied, an object will not move."

So how does it work? it uses microwaves - read the article to find out.

Tuesday, October 25, 2016

A nice physics blog

An interesting physics blog by PBS  with links to more physics blogs. According to the blog:
"What is The Nature of Reality? It’s a blog, and it’s pretty much the biggest question we could think of. "
Plenty of videos.

Monday, August 29, 2016

Small floating solar device boils water

An ingenious device using basic physics boils water in sunlight. From an article in Ars Technica:
"Tests in the lab and on the MIT roof showed that, under ambient sunlight, the absorber warmed up to 100 degrees Celsius in about five minutes and started making steam. That’s a first."
A good situation to work out the physics involved and discuss. (Photo - MIT)
Should be possible to make a less efficient copy of this device without the commercial selective absorber coating.

Thursday, June 30, 2016

More on gravitational waves

It seems that a new branch of astronomy is well underway with the discovery of more waves by LIGO, the new detector. Very interesting. See this BBC article. According to this:
"According to UK collaboration member Prof Bernard Schutz of Cardiff University, making a second detection proves the first was not just an isolated event, and that Advanced LIGO really does have the capability to open up a new cosmic realm to investigation."
OK - have to post this to catch my end-of-month deadline...

Monday, May 30, 2016

Astrophysics

This is defined as " the branch of astronomy concerned with the physical nature of stars and other celestial bodies, and the application of the laws and theories of physics to the interpretation of astronomical observations."

Interesting stuff. Am currently doing a MOOC on the subject at EdX focusing mainly on cosmology. You need a bit of calculus for this - advanced level mathematics or first year university. Recommended though.

Friday, April 29, 2016

Khan Academy

I am sure you have heard of Khan Academy. I took another look recently and it seems to have been upgraded.

Definitely a good source of learning videos for school level physics.

Wednesday, March 30, 2016

Gravitational waves

I have to say something on this. It has been on the horizon for many years and as elusive as the smile of the Cheshire cat. Not that I am qualified to say much more than how important it is and give some good links. So here are the links:
Caltech press release
Science article
Wikipedia