Recent content by billslugg

Piezo current only occurs where the crystal is squeezed in one direction and allowed to expand in the orthogonal direction in order to conserve volume. The Earth's core is indeed a crystal but it is surrounded by liquid thus there can only be isotropic forces, equal all around, thus piezo is not...

The antiparticle of the photon is the photon. The antiparticle of the neutron is the antineutron. The article has left out a word, here is the missing word in bold: "(Neutrons have no charge, so antineutrons also have no charge, but they have other equal and opposite properties on the subatomic...

You could consider going into a Black Hole the same as going to another universe since we cannot communicate with what's inside. What's inside can never get out. Might as well be another universe. Also, it might well be that you could go into a Black Hole, enter a worm hole and pop out inside...

When someone falls into a Black Hole, they don't know when they pass the event horizon. All they see is a dot of light straight ahead, darkness to the side and behind. They must deal with tidal forces. When an outside observer sees someone fall into a Black Hole, they see the person slowing...

Yes, magnetic fields are additive, extend to infinity and are absent only inside superconductors.

Welcome to SDC! I too am a retired engineer with 40+ years experience. I didn't see Sputnik but I remember the Echo balloons.

Yes, that is the article you mentioned and I found behind a paywall. I cannot access it.

The space industry does not decide what odds are tolerable, the FAA does that.

There is no preferred direction in space. Such re-radiated energy would be in all directions and we would receive some of it. Then we would see these photons in addition to the red shifted tired photons that we see. But we don't see anything in addition to them. In classical theory, the...

When these photons get tired and assume lower energy levels, where does the excess energy go?

The article is behind a paywall. There is a free download site I found but it's a big PDF file and they won't load any faster than 20kB/s. The Earth Impact simulator shows a crater diameter of about 2 miles. Manhattan would pretty much be trashed. At least broken windows out to 100 km. As for...

The nuke will be carefully selected such that the remnants of the asteroid are pushed away from each other at more than escape velocity. They won't come back together. Unfortunately public outrage would likely preclude any preemptive nuclear explosion in space since it would be a violation of...

Let's look at the total energy needed to move a bunch of fragments out of the way. This equation does not include the energy needed to bust it up. Just assume the nuke was only needed to move the pieces out of the way. The energy in joules = the amount of kilograms of push times the number of...

Yes, it is correct that there are numerous ways of insuring things burn up before they hit the ground but that has nothing to do with what I am talking about. I am talking about a total risk assessment. Given that we try to safely deorbit our rockets, we must still calculate the odds that the...

Suppose a potential impactor of 1000 foot (300 meters) diameter is detected with, say, 10 years to push it aside, how hard would we need to push on it? Assume a density of 4.5 which is typical silica based rock. Assume the impact point is dead center on the Earth, the worst possible point. The...