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Questions related from Derek Abbott
When analyzing a moving body with respect to a moving observer we can use the Galilean or Lorentz transformations. As we approach the speed of light we know the Lorentz transformation gives the...
11 November 2017 1,766 100 View
It is a well-known 'principle' in physics that only the two-way speed of light can be measured. Any experiment you try to construct to measure the speed of light only in one direction results in...
08 September 2015 7,707 6 View
We know that a decelerated charge emits photons. So you can visualize an observer in a stationary frame of reference that detects these photons. However for another observer in an accelerated...
28 November 2014 3,158 28 View
Are there any multicellular life forms that don't get cancer or where cancer is very rare?What can we learn from these cases?
20 July 2014 697 11 View
a) See here: https://www.youtube.com/watch?v=BE827gwnnk4 b) It takes 300 Hz to break a wine glass c) Speed of sound in air = 340 m/s d) Wavelength = 340/300 = 1.13 metres e) Speed of sound in...
18 May 2014 1,477 9 View
Imagine a parallel plate capacitor, where one plate is mounted on a spring and is allowed to move. Now connect a resistor across the terminals, so you have thermal noise driving the...
29 January 2014 9,208 3 View
Ideal pure classical randomness is deterministic and only appears random as a result of complexity and our ignorance of the system. Whereas a quantum event (eg, flip of a qubit or radioactive...
14 November 2013 1,516 15 View
A mental picture to understand this question is as follows. Imagine an alien spacecraft is on a collision course to crash into Earth and destroy us all. All the aliens in the craft are dead...
02 November 2013 7,324 19 View
First part of the question is: what are the absolute essential ingredients behind computation? You need (i) switches, (ii) interconnects, (iii) input energy source, (iv) memory, (v) feedback,...
23 October 2013 9,907 15 View
Many mammals have a bone called the baculum. Elephants and humans don't. Why? Is their a survival advantage specific to elephants & humans? When we look at the sequence of bones from homo...
30 August 2013 2,136 20 View
It is well known that babies cry just before sleep. Sometimes the cries have specific origins that cause pain or discomfort. But as everyone knows, even when all those factors have been...
28 August 2013 6,995 28 View
We model the physical world, by looking for invariances and laws, then building mathematical models on top of those. Often we have found that models can be superseded and our picture of the...
11 August 2013 4,141 93 View
One can obtain a rough upper limit for the maximum number of bits of information the universe could possibly hold as being somewhere around 10^122 to 10^124 depending on which parameters you feed...
11 August 2013 7,239 7 View
Are humans the only animals that are menopausal in females? If not, which are the others? What other relevant factors do they all have in common? Does the menopause confer the same survival...
11 August 2013 9,484 7 View
The Buffon's needle experiment is one that you can repeat many times, and in the limit it will give you an increasingly accurate estimate of pi the more you repeat the experiment. Simply stated:...
06 July 2013 2,902 6 View
If we look at the formula for the inverse square law for force between two charges Q1 and Q2, a permittivity term is in the denominator. If the permittivity was hypothetically zero, the force...
21 June 2013 1,155 9 View
Alice & Bob enter a game where each have a necktie and they call an independent judge to decide who has the better looking necktie. The judge takes the better necktie and awards it to the other...
13 June 2013 1,034 26 View
Here is the problem: 1. Alice wants to phone Bob. 2. Alice dials Bob's number and the person at the other end claims to be Bob's son Charles. 3. Bob and Charles have indistinguishable voices,...
08 June 2013 4,503 15 View
Is there a proper way to determine when and when not to add quantities in quadrature (ie. adding the squares)? Or is it one of those black arts? In what follows, is what I actually teach to my...
01 June 2013 9,022 5 View
Can a single photon source be set up in a way that we know the time when each photon is emitted? It seems to me that it ought to be impossible to determine the time. If it were possible, then in...
28 May 2013 2,611 9 View
More journals these days are requiring an ethics statement if a human was involved in an experiment. But are there some trivial no-risk classes of experiment for which no approval is universally...
23 May 2013 4,970 40 View
a) My microwave oven operates at 2.45 GHz and has a mesh screen behind its window. b) My smartphone receives both WiFi connections as well as standard cellular calls. c) I put my phone in the...
18 May 2013 6,163 2 View
When integrating using the method of residues, one needs to check if the integrand satisfies the Cauchy-Riemann equations first. However, it is possible to have an integral that doesn't satisfy...
12 May 2013 3,616 11 View
It's generally thought that mtDNA is only maternally transmitted. But is there any evidence at all for paternal mtDNA transmission? What about during ICSI? And if so, what are the implications?...
04 December 2012 3,963 3 View
It is well-known that in quantum mechanics, [position, momentum], [angle, angular momentum], [energy, time], and [phase, particle number] are all conjugate pairs and have an uncertainty relation....
02 December 2012 8,235 76 View
It was always thought impossible to have a closed-form formula that can calculate an arbitrary Nth digit of pi, until Borwein produced a formula in base 16 in the mid-1990s. My question is why...
26 November 2012 1,870 31 View
