Recent content by dgwsoft

DOH! of course the Planck mass is not the smallest physically meaningful mass. But now wonder why that is though to be true of the Planck time and length? Anybody know?

If you somehow could condense a carbon atom (mass 2x10^-26 kg) down to its Schwarzschild radius (the size at which it would become a black hole) then that is 3x10^-53 m, which is much smaller than the Planck length (1.6x10^-35 m). Furthermore a black hole of mass less than the Planck mass...

Special Relativity, certainly. The Lorenz Transformation was already well known. But we could still be waiting for General Relativity.

At 0.1c you could travel to Saturn in about 12 hours. Do you need travel in your solar system to be that fast? If you are happy for the journey to take days or weeks then a much slower (and more plausible) propulsion system would do. (Though still much faster than anything we have today).

1. How could a spacecraft traveling at 10% the speed of light be slo The same way you speeded it up to 0.1c in the first place. For any plausible high-speed* propulsion system you need to allow the same time to decelerate at the end of the journey as to accelerate at the beginning. If you...

Pole breaks - US version Sorry, that must be because it is on the BBC. It must be somewhere on the interweb you can see it. The competitor is Lazaro Borges, at the Olympic Games in London, 8 August 2012. Try these...

It is a video. Maybe you do not have the right plug-in? The pole is shown breaking into three pieces, in slow motion, from several angles.

http://www.bbc.co.uk/sport/0/olympics/19179092 Is this an example of the Feynman spaghetti problem?

Thanks for posting that, Brian. Your book was in my Christmas stocking this morning so I will read it before commenting further. (I also have The Grand Design by Stephen Hawing, and Hubble: Window on the Universe, so its a scientific Christmas for me!)

See also this thread: https://www.physicsforums.com/showthread.php?t=561511 and reply from the man himself (becox).

Good question. It depends how you bring them into the same frame of reference. If you accelerate clock A until it is stationary relative to clock B, then clock A will have ticked fewer times (since the time at which they passed each other, and were in close proximity). However if you If you...

Thanks for responding, Brian. Your book is already on my Christmas list :smile: I think I follow your double-well example. It is effectively a model of the hydrogen molecule. So yes, there are in principle two energy levels however far apart the protons get, and for N protons, N energy...

http://www.bbc.co.uk/programmes/b018nn7l I did enjoy Brian Cox's program on quantum mechanics last night, but one bit left me thinking "no, that's not right!". The gist of it was that all the electrons in the universe have to be in constant communication to ensure that no two of them are...

Faster-than-light neutrino experiment to be run again With nanosecond proton pulses. As reported by the BBC http://www.bbc.co.uk/news/science-environment-15471118

I do not know anything specific about this experiment. I was an astronomer 25 years ago (Atmospheric cherenkov, 1TeV gamma rays). But in general there are two kinds of statistics you need to watch out for. The first is a large effect with low significance. That is obvious and will not catch out...