Jump to content


Resident Experts
  • Content Count

  • Joined

  • Last visited

  • Days Won


Janus last won the day on September 11

Janus had the most liked content!

Community Reputation

1063 Glorious Leader


About Janus

  • Rank
  • Birthday August 28

Contact Methods

  • Website URL

Profile Information

  • Favorite Area of Science

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Janus

    Today I Learned

    TIL that a skilled scam-baiter can waste 36 hrs of a scam call center's time in an attempt to scam one person. I recently have been watching some you-tubes edited from the Twitch live-stream of a scam-baiter. They can be entertaining, while giving you a look into just how many these scams work. (he has done tech support, fake refund, IRS, social security, and immigration scams) One of the best was when he faked going to Best Buy to buy gift cards for the scammer, only to have his Uber driver drive off with them. ( this one required sound effects and a friend playing the part of the driver.) Generally, he can't waste their time for more than an hour or two at most before the scammer either gives up or the scam-baiter just reveals himself. In this case, in an attempt to scam someone, who they thought was an 87 yr old woman, this call center, over many, many phone calls spread out over weeks, spent 36 hrs on the phone with their intended victim. The edited you-tubes of this was broken up into 10 episode of ~ 3/4 - 1 hr long each, and I just watched the last one. It was interesting to see how the baiter kept them on the hook, always teasing with a big score that never came, and how more and more desperate the scammers got.* *And in this case, it lead them to revealing just a bit too much info, which the scam-baiter turned over to authorities.
  2. That "Narrow band" is a lot wider than it looks to the naked eye. You are only seeing that part that is bright enough. As an example, consider the Andromeda galaxy. To the naked eye it looks like a small fuzzy spot, but if you could see it in full, it would appear like this in the sky. Several times wider than a full Moon. What we see by naked eye is just the nucleus of the galaxy. But just because we don't see the disk by naked eye doesn't mean that it doesn't hide the light from galaxies behind it.
  3. Each set of images shows a series of chosen moments for each frame. Those moments are chosen as they represent when a pair of clocks pass each other. The numbers tell us what clocks at those positions read at that moment according to the chosen frame. So each successive diagram in the image represents a single moment in time. Thus in the first image of the first set, All the clocks on the E-X rod read the same time(12:00) at that moment, while the clocks along the B rod do not ( reading 12:00, 11:31:12, and 11:12 as you go from left to right) at that same moment.
  4. Spacecraft during re-entry only get up to ~ mach 25, and even at that speed, the air is heated to a plasma state. Craft like Apollo and Soyuz use ablative shields that burn off to deal with it. And this is in the upper part of the atmosphere, where the air density is very low.
  5. Your error is that you again are not taking relativity of simultaneity into account. To illustrate, we can put clocks at the end of rod attached to B and at the point's along the rods. Thus from The E-X rest frame you get this: The green boxes indicate two clocks passing each other and their respective readings as they do. In the rest frame of B, you get this: Comparing the the times shown in the green boxes as clocks pass each other agree with those in the first image. In each image, there is a an instance when two pairs of clocks pass at the same time, but they are different pairs of clocks in each image. This just illustrates that, with the Relativity of simultaneity, events that are simultaneous for one frame of reference are often not simultaneous for another.
  6. About 10% of the universe is "hidden" from our view by the bulk of our own galaxy (20% if you only consider the visible part of the spectrum). This won't change much due the rotation of the galaxy as this is mostly due to having to view through the disk of the galaxy.
  7. My mistake, I thought you were here for a rational discussion.
  8. While not intentionally, a fix to a design problem provided one. One of NASA's missions to a moon of an outer planet required communication between an orbiter and lander. This used a protocol which involved a narrow frequency tolerance. The problem arose because the tolerance was made too tight and the transmission frequency of the lander was off just a bit. The "fix" they came up with was to alter the orbiter's orbit so that at specific times, its velocity with respect to the Lander caused a Doppler shift which compensated for the drift. The lander would dump its gathered data during these "window"s. Now if there had been an "ether wind", the Moon's orbit around its planet, and the Planet's velocity would have had an effect on that Doppler shift. In other words, Not only would they had to account for the relative velocity between lander and orbiter, but these other motions as well. And since these motions changed with time relative to the orbiter's orbit, NASA would have had to either keep adjusting the Orbiter's orbit or changing the "transmission window" to keep up. They didn't. The only thing they needed to concern themselves with was the relative velocity between orbiter and lander, which would not have worked if there had been an ether wind. T
  9. Personally, I subscribe to Bertrand Russel's version of liberalism. It's not the views you hold, but how you hold them. Always cognizant of the possibility that they could change upon the discovery of new information.
  10. The reason the tidal interaction transfers angular momentum from Earth to Moon is that the drag between the Earth and tides causes the tidal bulges to be pulled "ahead" of the Moon. If you removed this drag completely, the bulges would remain lined up with the Moon, and there would be no momentum transfer. Increasing the drag would allow the spinning Earth to pull the bulges even more out of line, increasing the tendency transfer energy to the Moon. As far as energy goes: Most of the energy lost by the Earth through its slowing rotation is not transferred to the Moon, but is lost as heat.( the Moon gains less orbital energy than the Earth loses rotational energy). So it doesn't really work to think of energy "used" by the turbines as being taken away from energy given to the Moon. Look at it this way. If we just increased the drag without generating electricity, we would increase the amount of energy the Earth loses in rotational energy both by transferring some to the Moon, and by waste heat. By extracting some of that energy by converting it to electricity, you are making use of a part of that energy that would have been lost as heat.
  11. So, I read that Trump planned his town hall after hearing about Biden's, and his intent was to "blow Biden out of the water" in the the viewership ratings ( you know how important Trump thinks TV ratings are). The ratings came in: Biden's were better. Trump's blood must be boiling, and I wouldn't want to be the flunky he' s going to lay the blame on.
  12. Tidal interaction between the Earth and Moon transfers angular momentum from the Earth to the Moon, slowing the Earth's rotation and raising the Moon's orbit. Turbines intended to extract energy from the tides would increase the ocean tide- Earth drag. This would magnify this transfer. In effect, the energy comes at the cost of the Earth's rotation. But as Swanson alluded to, a comparison of the comparative magnitudes would be informative as to the overall effect on the rotation.
  13. A couple of points: Galactic rotation curves show that orbital velocity remains nearly flat as you move outward. For the galaxy to appear to rotate as one piece, they would need to increase proportionally with R. At the same velocity, a star closer in still takes less time to complete an orbit than one further out. This image plots the various curves. note that the vertical axis is in km/sec. So, why don't we see the spiral arms "wind up"? It is because the spiral arm formation is due to a different mechanism than the orbital motion of the stars. They are produced by density waves moving through the Galaxy. Since these waves do not travel at the same rate as the rotation, stars drift in and out of them. A bright spiral arm is where a wave has the highest density. As a result, you get a higher rate of stars being born there. This includes massive, bright stars. But these stars have short lives, and burn out fairly quickly. By the time the stars in a spiral arm drift out, these brighter stars have spent themselves and you are left with the dimmer longer life stars. The spiral arms look bright not because they contain that much more stellar material, but because they contain a larger percentage of bright stars. This bright star vs. dim star paradigm happens in our own night sky. If you go out on a clear night away from city lights, you will see a sky full of stars. But you are really only seeing, for the most part, brighter than average stars. Our own Sun would be only visible by naked eye over a distance of a few 10's of light years. The vast majority of stars we see are much further than that, they are just much brighter than our Sun. Within 17 light years of the Earth, there are ~50 stars, only 10 of which are visible by the naked eye. Some of it might be objects like black holes, etc ( MACHO's, or MAssive Compact Halo objects) Though there are limits as to how much these can contribute due to how they would have effected the early formation of the universe. Some of it could be made of particles which don't interact via electromagnetism (WIMPs, or Weakly Interacting Massive particles) There is nothing that rules out such particles (In fact, the neutrino has these characteristics.) And don't let the fact that it makes up so much the universe mislead you. It is also spread out over much larger volumes than the more compact structures like galaxies. It is estimated that the density of dark matter within our solar system is so low that the total of its mass would only equal that of a small asteroid.
  14. The distance between c and E and The distance between c and X are the same. So are you claiming that an observer at c will say an object going from E to X ( along the red arrow) traveled zero distance? Of course not. The same holds for an observer at d, or e, f and g. They all would say that an object moving from E to B traveled the same distance in the same time. It doesn't matter how far you put your observer away, the traveled distance doesn't converge to 0, but remains the same.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.