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  1. phyzguy

    I How to find Heliocentric latitude data for each planet?

    The Earh's orbit is basically fixed in space, but it does rotate slowly. This is called the precession of the perihelion. This is not to be confused with the precession of the Earth's axis, which takes about 26,000 years to complete a cycle. The precession of the perihelion, which is what you...
  2. phyzguy

    I Decay constant of Different Elements and Isotopes?

    Rather than a law, there are patterns of nuclear stability. Referring to this chart from Wikipedia, you can see that stable isotopes fall along the valley of stability. This is a line with equal numbers of protons and neutrons for low atomic numbers, but bends towards larger numbers of...
  3. phyzguy

    B LIGO to go back online today after updates

    This pdf has a good summary.
  4. phyzguy

    I Some questions about this vintage periodic table

    It looks just like the one that hung on the wall of my high school Chemistry class back in the late 60's/early 70's.
  5. phyzguy

    B Night Sky of Alpha Centauri: Sol as a Bright Star

    How can that be? The sun and Alpha Centauri are only 4 light years apart. It's like saying that Los Angeles is 3000 miles from New York, but 6000 miles from Brooklyn.
  6. phyzguy

    Fortran Fortran 77 code to debug

    Have you tried using f2py? It allows you to compile the fortran code as a Python module.
  7. phyzguy

    B Night Sky of Alpha Centauri: Sol as a Bright Star

    The difference in the appearance of the night sky between A and B would be negligible.
  8. phyzguy

    B Night Sky of Alpha Centauri: Sol as a Bright Star

    I think the OP's question is what would a star map look like from Alpha Centauri. Most of the distant stars would look about the same, but the positions of the nearby ones would change. In what constellation would the sun fall? I've never seen such a map, but it would be very interesting. We...
  9. phyzguy

    A The Exceptional Jordan Algebra in physics

    I think there are more important papers on this topic. I found this paper by Bhatt, where they calculate the fermionic mass rations from the eigenvalues of the matrices of the Jordan Exceptional Algebra to be very interesting.
  10. phyzguy

    Is ChatGPT just searching sites like stackexchange?

    When I called it on that, it gave me a detailed list of the monotremes that lay eggs.
  11. phyzguy

    Is ChatGPT just searching sites like stackexchange?

    Apparently it has learned:
  12. phyzguy

    The James Webb Space Telescope

    This makes a lot of sense, and is much more correct than what I wrote. Thanks for the detailed explanation.
  13. phyzguy

    The James Webb Space Telescope

    The six diffraction spikes are more caused by the three supports that support the secondary mirror. As said above, the Hubble has four secondary supports, so you get four diffraction spikes. The three Webb supports lead to six diffraction spikes, because you get one opposite to the support as...
  14. phyzguy

    Tusi discovering laws of planetary motion before Kepler?

    Since the Tusi Couple is a hypocycloid, and the actual orbits are ellipses, how could this be said to be a discovery of the planetary laws before Kepler? Also, what about Kepler's second and third laws, which are probably more important than the first?
  15. phyzguy

    B Jupiter from James Webb

    All the wavelengths in this picture are in the infrared and far outside our visible range. If you plotted this picture using "real" colors, it would be black.
  16. phyzguy

    Anybody with experience with SciPod?

    Turns out there is in fact a substantial fee, so I told them I'm not interested. Why should I pay them to help populate their website? Thanks for the responses here. It never would have occurred to me to ask if there was a fee.
  17. phyzguy

    Anybody with experience with SciPod?

    No fee was mentioned. Here is the main part of the message I received. I am inclined to do it, but I thought I would check here first: "I would like to speak with you about your studies and our interest to feature your work in our video publication, SciPod. If you are not already familiar...
  18. phyzguy

    Anybody with experience with SciPod?

    Hi all. I've been approached by SciPod to contribute a short video on my work. Has anyone here done this? Are they reputable? Are they worth the effort? Here's a link:
  19. phyzguy

    News ChatGPT fought the Law and the Law Won?

    Which is as it should be isn't it? If some link on the internet tells me to go shoot somebody and I do it, aren't I at fault?
  20. phyzguy

    A Is there a way to convert distance modulus to get H(z) values

    It's easy to convert distance modulus to distance. See this Wikipedia page for example. But do you also have redshift for these objects? How can you plot a Hubble curve without redshift data?
  21. phyzguy

    Any advice to make this Op-Amp temperature controller circuit work?

    Did you check whether your CL100 BJT is still functional? Your circuit will reverse bias the emitter-base junction of that BJT when the output of the second op-amp goes negative. Reverse biasing the emitter-base junction of a BJT usually destroys it.
  22. phyzguy

    I Is the light from Andromeda truly blue shifted?

    No! Its redshift is "actually" negative. It's redshift of -0.001 means it is moving toward us at 0.001*c ~=300 km/sec. The Hubble constant is about 70 km/sec/Mpc. At Andromeda's distance of 0.75 Mpc, the cosmological redshift is about 50 km/sec, which is much smaller than the 300 km/sec that...
  23. phyzguy

    B Aperiodic Tiling with a single tile shape

    I just saw this today! I want to tile a floor with these tiles. I wonder how long it will take before someone starts manufacturing them?
  24. phyzguy

    Python UnimplementedError: Cast string to float is not supported

    For example, googling "tensorflow cast string to float" returns a lot of hits.
  25. phyzguy

    I Schutz and the Hubble Flow

    In the excellent paper by Davis and Lineweaver, they list all of the people that have gotten this wrong, including some big names.
  26. phyzguy

    B What is causing destructive interference in double slit experiment?

    I like this quote from Feynman, "Do not keep saying to yourself, if you can possibly avoid it, 'But how can it be like that? ' because you will get 'down the drain', into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.”
  27. phyzguy

    Is ChatGPT just searching sites like stackexchange?

    I may be wrong, but I don't think ChatGPT has real-time access to the internet. It was trained off internet content, but it can't search the internet to respond to your prompts.
  28. phyzguy

    I Interpreting the Orbit of S2

    As @pasmith said, reading from the diagram, the semimajor axis is about 0.1". This is the θ in your second formula. It is not a declination, it is the angular size of the orbit.
  29. phyzguy

    B Ambiguity in Avogadro's Law?

    You need to accept that Avogadro's law is true to a pretty high degree of accuracy, and has been tested for over a hundred years. So if it is very strange to you, it can't be that the law is wrong. It must be that you are not understanding what it says. The law doesn't say anything about...
  30. phyzguy

    B What is the best source for this star data? (M44 Beehive Cluster)

    If you haven't used Python, it's probably best to query Simbad directly from the web interface. Below is a screen shot of the query. It's the same basic syntax and returned the same list of 2162 objects.
  31. phyzguy

    B What is the best source for this star data? (M44 Beehive Cluster)

    I just query Simbad using Python. The code snippet below should give you what you want. It returned 2162 items. It's going to be up to you to determine which ones are actually physical members of the Beehive cluster and which ones are chance associations. import numpy as np from...
  32. phyzguy

    B What is the best source for this star data? (M44 Beehive Cluster)

    I tried that, but many of the stars are too bright to be included.
  33. phyzguy

    B What is the best source for this star data? (M44 Beehive Cluster)

    I would start with Stellarium, which is a free download ( You just click on the stars you are interested in, and you will get everything you listed except the spectrum, although you will get the spectral type. I'm attaching a screenshot.
  34. phyzguy

    A Black hole mass coupled to expansion -- astrophysical source of dark energy?

    Thanks for this explanation. If this model is correct, does that mean that there are two types of black holes? (1) "normal" black holes formed from the collapse of ordinary matter, and (2)these more exotic black-hole-like objects that are filled with dark energy?
  35. phyzguy

    How does tire pressure affect distance traveled by a bicycle coasting to a stop?

    If you actually do the experiment, you will find that your initial assumption of, "with negligible air resistance" is a bad assumption. Unless you are moving very slowly, air resistance is the primary drag on a bicycle.
  36. phyzguy

    Major Nuclear Fusion Milestone: Ignition Achieved

    I don't know why you would call it a"shabby little secret". It was all very clearly publicized. Those numbers were never hidden. You just rely too much on popularizations of the results rather than reading the true stories.
  37. phyzguy

    How to add HZO as an Oxide gate in Silvaco TCAD?

    Here are some examples from Silvaco:
  38. phyzguy

    Mystery fan controller

    Ah you keyed on that KTS-011. I didn't think of that. Thanks again.
  39. phyzguy

    Mystery fan controller

    Yes!! That's looks just like it. Thank you! How did you find it?
  40. phyzguy

    Mystery fan controller

    Does anybody have any info on this fan controller? I don't even know what to Google, because I don't know what that second character is. Any help?
  41. phyzguy

    I cannot work out constants a and b --

    You are given three things: (1) v = ay + by^2 where a and b are constants (2) at 1.5 mm from the surface the velocity is 75 m/s (3) at 3.0 mm from the surface the velocity is 105 m/s. From these, you should be able to set up two equations with two unknowns and solve them for a and b. Have you...
  42. phyzguy

    I Modeling the Earth and Sun (2 body orbits) using general relativity?

    Yes, in general it's very difficult. You need to simultaneously solve for the metric and the motions of the bodies in a way which is self consistent. People worked for decades and were unable to get the codes to converge. Then in the early 2000's they evolved new techniques which allowed the...
  43. phyzguy

    I Modeling the Earth and Sun (2 body orbits) using general relativity?

    This is a very interesting problem. For the Kepler orbit (Newtonian, no GR), it is possible to re-write the equations of motion to read: $$\frac{d^2u}{d\phi^2} + u = \frac{GM}{h^2}$$ where u = 1/r where r is the radius, and h is the specific angular momentum, which is a constant of the motion...
  44. phyzguy

    Contractions in English

    I agree. I hear "this class". This reminds me of when I was learning French. I had one of the Harry Potter books on audio book, and I had the text copy as well. I would listen to the audio and say to myself, "They are just not saying all of those words!" Then I listened to it over and over...
  45. phyzguy

    I The circumference of a circle

    Certainly the string length is a real number. How do you conclude that it is also rational?
  46. phyzguy

    A Has the merger of a neutron star and an anti-neutron star been modeled?

    Probably nobody has spent any effort doing this because it is highly unlikely that an anti-neutron star exists in our universe.
  47. phyzguy

    Stargazing On Tidal Disruption Events

    Thank you for running this. This backs up what I have been trying to say. The neutron star is simply too tightly bound to be tidally disrupted.
  48. phyzguy

    Solve the given first order differential equation

    I don't see what your problem is. You found that $$y=-e^{\tan(x) -1}$$ Isn't this answer (B)?