1. ## exchemist

Senior Members

29

326

Moderators

26

47126

3. ## iNow

Senior Members

23

23259

Moderators

19

10709

## Popular Content

Showing content with the highest reputation since 05/13/21 in all areas

4 points
2. ## mystery glassware identification - anyone knows what this is ?

A Part of a modified Soxhelt extractor probably.
3 points

3 points
4. ## Safer for a healthy 32 year old: contracting COVID or getting the vaccine?

There is a useful article here about the care needed when interpreting raw numbers from VAERS: https://www.ibtimes.com/over-900-died-after-receiving-covid-19-vaccine-experts-say-data-misinterpreted-3153820 So the answer I think is no, they have not been investigated for possible causality, nor are there necessarily grounds for doing so. By the look of it, it may be the old post hoc ergo propter hoc trap. It seems quite hard to find the data you are looking for viz. the risk of fatal side effects of the vaccine in fit and healthy under 30yr olds. I have been able to find the relative
3 points
5. ## Cryptocoins: who pays the huge energy?

It's not just that China as a whole controls the vast majority of the mining. It's also that the top four Chinese mining pools control over 60% of the bitcoin hashrate, and have done so ever since I started tracking it several years ago. https://btc.com/stats/pool Basically, the conditions for a so-called 51% attack already exist and have always existed. These mining pools can wake up any morning they like and steal everyone's bitcoin. The only reason it hasn't happened yet is that they haven't done it. Not because they can't. ps -- Just to clarify what a 51% attack is, the idea
3 points

3 points
7. ## The intent of Israel bombing AP/Al Jazeera offices

When are you going to contribute something of value?
3 points
8. ## The wisdom of the 5 post limit.

Here's proof of the wisdom of the 5 post initial limit agains spammers. Suggest using this to explain the limit to genuine new members.
3 points
9. ## The intent of Israel bombing AP/Al Jazeera offices

Oh, please. This isn’t about the Israeli people or even about the country itself. This is all about Benjamin Netanyahu being at his weakest ever point since first getting elected, being unable to even form a coalition government, and facing numerous corruption charges. This response is his way to deflect and redirect attention so he can retain power like all good autocratic leaders do. It’s part of the playbook, and we’ve seen this exact movie plot multiple times before.
3 points

I wrote it.
2 points
11. ## Should academic research establishments be political?

Three points: 1) An integral part of higher education and research is critical examination and questioning of the status quo - be it in the context of physics, biology, sociology, history, art etc. This means that the central mindset within higher learning and research institutions is fundamentally progressive, but not necessarily in the political sense. We have seen universities at the forefront of socio-political change, especially during the Bolshevik revolution, the civil rights movement, Arab spring, etc. They tend to be agents of change rather than conservatism, by nature of what
2 points
12. ## Should being within six feet of someone while Coronavirus going on be considered assault?

Yes, probably. I have been going through quite a few student theses recently and my brain just blanks out things that do not make sense for self-preservation, I think.
2 points
13. ## The problem of free energy in the special theory of relativity

One more issue: the statement above is not consistent with the setup: (bold by me in the quotes above) A friendly reminder: You are posting on a forum where plenty of members are experts; scientists, teachers, engineers and more. Imagine what you would be able to learn if you posted questions instead of incorrect claims. You would get advanced answers, good references, reading advices, links to free online courses etc. You seem interested in physics and capable of attempting basic mathematics. The predictive power of the current models of mainstream physics is quite good,
2 points
14. ## Should academic research establishments be political?

There many articles about that and even a wikipedia page https://en.wikipedia.org/wiki/Trump_administration_political_interference_with_science_agencies. The only thing Biden had to do was basically not to do that. If you have missed the last year, there is a little thing called COVID-19 and one of the presidents said that it would go away on its own. Guess which one that was. A colleague of mine basically characterized the left-right attitude to science the following (aptly, I might add): the left ignores science that hurts them politically. The right actively antagonizes and suppre
2 points
15. ## What is the Purpose of Life ?

This isn’t a forum for bad poetry. It’s a forum for science enthusiasts
2 points
16. ## Did Albert Einstein come up with his theories all by himself?

You must distinguish between the many different contributions E made to physics. But I assume you mean relativity: special- and general relativity. For special relativity, the time was ripe for its discovery. Several physicists before (Fitzgerald, Lorentz, Poincaré, and several others) already guessed the correct formulas. It was even Poincaré that called the Lorentz transformations that way. But Fitzgerald and Lorentz used more or less ad hoc assumptions to derive them, e.g to explain the null result of the Michelson-Morley experiment. Poincaré's views already circled around the concept
2 points
17. ## If the development of science happens to be blocked, what a politician should vote for?

! Moderator Note Either provide details that can be analyzed or this thread will be closed. As it is, this looks like some crackpot lost his mind over the rejection of his misinformed ideas and is now whining big time. There's NOTHING to discuss in this thread's current form. Do better!
2 points
18. ## Denoting ∫ (f(x) + dy/2)dx as area under a curve?

Yes, both methods approach the same limit. In this case, you can explicitly write that down: Assume you integrate from 0 to 1, and you split the range into N intervals of equal length. In the first case, your integral approximates as $I_{1, N} = \frac 1N \sum_{i=0}^{N-1} f(i/N) = \frac 1N \left( f(0) + f(1/N) + f(2/N) + \dots + f((N-1)/N) \right)$. In the second case, your integral approximates as [math]I_{2, N} = \frac 1N \sum_{i=0}^{N-1} \frac 12 \left( f(i/N) + f((i+1)/N) \right) = \frac 1N \left( \frac 12 f(0) + f(1/N) + f(2/N) + \dots + f((N-1)/N) + \frac 12 f(1) \right)
2 points
19. ## Denoting ∫ (f(x) + dy/2)dx as area under a curve?

The result of the integral doesn't depend on which approximation you use. The second one is called the lower Riemann sum. There is another one with starts with what you would call $$f\left(x_{0}+\triangle x\right)$$ instead of $$f\left(x_{0}\right)$$, and ends with $$f\left(x_{1}\right)$$ instead of $$f\left(x_{1}-\triangle x\right)$$ It's called the upper Riemann sum. Your expression differs only in a second-order term in $$\triangle x$$. You only see a big difference because your $$\triangle x$$ is enormous in the image. You can actually do an even better fit by taking a polygonal appr
2 points
20. ## How to capture electrons from photoelectric effect?

Not hydrogen atoms. You want a conducting solid material, such as a metal plate, because the idea - at least as I recall it - is that with light above a certain frequency a current flows in a circuit, due to the emitted electrons, whereas below that frequency it doesn't. The experimental setup to "catch" the emitted electrons is shown in this diagram from the Wiki page: https://en.wikipedia.org/wiki/Photoelectric_effect#/media/File:Photoelectric_effect_measurement_apparatus_-_microscopic_picture.svg You can certainly ionise hydrogen or other gases with light with energy above the ion
2 points
21. ## Simple yet interesting.

This statement is false on its face. That's why readers are put off and have no idea what you're talking about. Could you give a specific example? Say I have a line segment of length 2 and another of length 3, both with one end at the origin of the x-y plane. Can you show how you get the third side? What additional information is supplied? Please be specific. No need for extraneous discussions of the travails of your long-suffering teacher. Just show an example of two lengths and how you determine the third one. Also, what does pnp stand for? Give a specific, completely worked
2 points
22. ## Will COVID be eliminated once everyone is vaccinated?

Polio is still endemic in Afghanistand and Pakistan and I believe there have been irregular detections elsewhere. To OP, at this point it is not clear. If vaccination was available early in the pandemic and/or if the infection levels where kept at a low level until now, and if everyone was getting vaccinated, then the answer would have been a yes. However, one should take a step back in understanding how eradication works. It is not necessarily just a matter of vaccination, but it is about creating a situation where an infected person is unable to infect enough folks to sustain patho
2 points
23. ## Notable Interviews on Climate Change, Religion fundamentalism/ID and Racism

Science and morality are different disciplines - one is what we observe in the universe, the other is what we bring to it. Morality is not so straight-forward that we can afford to discard the millennia of thinking that has shaped our cultures. Instead we should be building upon that base, taking what is useful from our mythologies, and creating new ones in the shape of our aspirations. If they are such idiots why give them credence by engaging with them? Such people have the same mentality that has people believing in a flat earth and lizard people ruling the world. No one bel
2 points
24. ## Inertial Drive

Most people see a conflict between their observation and their understanding of physics, and conclude their understanding is flawed. These folks would look at the explanations and gain understanding. A few others see this conflict, and conclude the laws of physics are wrong. John2020 is not the first, and will not be the last, to take this stance here. But there’s no traction to it. The laws of physics are not wrong. The extra frustration is that this is a fairly trivial case and the misunderstanding is of such a fundamental concept. There’s no effort to gain anything, because of the deni
2 points
25. ## Inertial Drive

We have thought about it. Not everyone can watch a given video for various reasons, and they should not be shut out of the discussion. Videos can’t be quickly scanned like written material, so it’s an unreasonable investment of time (especially since videos follow Sturgeon’s law) Videos can’t be easily quoted. And too many people would (and have) posted only to drive traffic to their channel. The evidence really isn’t the issue here. Nobody has tried to argue that there isn’t motion. That you have insisted on things that are contrary to Newton’s laws of motion is the issue. Complaining ab
2 points
26. ## The Official JOKES SECTION :)

I was going to get my mail a couple days ago and a couple misguided youths had placed a (very realistic) rubber rattlesnake in the sidewalk to the mailboxes. They rolled out of a car across the parking lots reveling in laughter saying "you might be white headed but you still have the moves!" I must admit I found a few old moves real fast.
2 points
27. ## Comparing Corona Virus Success Stories with Abysmal Failures

The use if siRNA itself to knock down genes is universal and been discussed as an antiviral for quite some time. The tricky bit is the delivery to target sites. In this case, they took advantage of the fact that certain lipid nanoparticle compositions have been shown earlier to accumulate in lungs, so when delivered intravenously they were able enrich the siRNA in lung tissues. For other tissues and cell targets (which include HIV) it may be more difficult to deliver the siRNA there. Difficult to tell, normally they need a controlled trial on humans first to make sure that it i
2 points

2 points
29. ## Moment Distribution Method - Frame

The lecturer has posted a solution to solving the problem using the above method with only a vertical force. Problem solved. But upon reflection, I looked at a textbook & the only problems (MDM) which include frames & horizonal forces took sway (or horizontal deflection) & principle of superposition into account to solve the problem.
2 points
30. ## Hijack from Paper: A causal mechanism for gravity

Five responses from you in that thread. So you’ve nailed it again. And the responses were pretty consistent, as is your misunderstanding of Newton’s laws. My counteroffer: no. What would likely happen is we would get inundated with nonsense for a week, which is unacceptable. The current protocol requires that a thread-starter get to the point and respond to feedback. i.e. we require they not waste anyone’s time. We’re not about to give a crackpot leave to ignore science for a week so they can post their entire manifesto. We don’t owe them a stage and a microphone
2 points
31. ## Earth The Size Of A Tennis Ball

If the Earth was the size of a tennis ball, this video explains the size and scale of the universe. This video will make you feel very small.
2 points
32. ## Consideration of the difference between the use of the term 'space' in Physics and Mathematics.

Which is what I was implying.
2 points
33. ## The intent of Israel bombing AP/Al Jazeera offices

Maybe they could just stop forcing people from their homes and stealing the land on which they’ve settled, or not attack them during religious services… or let them have food and vaccines without blocking them.
2 points
34. ## Cryptocoins: who pays the huge energy?

And another just for fun:
2 points
35. ## Evidence of Human Common Ancestry

It looks to me as if the answers to your many questions can easily be found, just by a bit of reading, if you really want to know the answers. However, my rather jaundiced experience of those who describe scientifically literate people as "evolutionists" is that they actually don't want to know the answers, as the answers don't fit their (naive) religious beliefs. I hope you are not one of those. Assuming pro tem that you are not, brief answers to some of your questions would be as follows:- Bees: pollination by insects is just one of many ways that it takes place. So insects were no
2 points
36. ## The universe is flat? (split from Time for a different view)

No. 'Flat' means that e.g. parallel lines stay parallel, no matter how far you compare their distance between them. Best example is two light beams. When these do not converge or diverge, the universe is flat. It is difficult to imagine how a positive curved universe can be infinite because it is closed in itself, like the surface of a sphere. But with negative curvature and flat space that problem does not arise. Just take care that the universe seems to be flat on average. Locally, due to mass and energy, the flat universe can be curved.
2 points
37. ## Laser and circuit

1. Things are not true just because you say them. Stating that lasers redirect current is not something you can base any discussion on until AFTER you establish it is true. 2. Regarding voltage being consciousness see 1), but also you aren’t permitted to bring up speculations in other threads. That’s not a statement that has any basis in science. I am loath to touch it, knowing where it must have come from.
2 points
38. ## Crazy New Perspective on Gravity

The part we can perceive? That is called the observable universe, which is entailed by "c " and the time that the EMR has had to reach us within the known age of the universe and the expansion rate. That's nice....as a lay person myself, I re-enforce my knowledge by reading reputable books, then through forums such as this, if there is something I don't understand, I ask questions. The general picture of the evolution of space/time/universe is a model that to me anyway, makes a lot of sense. Prior to t+10-45 seconds, where the BB and laws of physics does fail us, I also have my own han
2 points
39. ## Rand Paul Called Fauci a Liar

The entire NIH grants database is searchable. Here's the results for Wuhan University. Two R01's awarded to the same PI for AIDS related immunology research. Here's the Chinese Academy of Sciences results. None awarded by the NIAID. That took all of two minutes to disprove. Unless, another institution gave the a subaward from their NIAID grant, but the fact the author's name is not given, the paper not cited and the grant number isn't stated, it's rather impossible to verify that situation.
2 points
40. ## Ionisation in radioactive decay of atoms

Say you have some uranium (VI) fluoride UF6, and it decays. It spits out a helium nucleus and forms Thorium and helium. But the helium nucleus is shot at at a huge speed. So, according to the conservation of momentum, the Thorium nucleus must be kicked the other way by the recoil. It is usually set moving so fast that most of the fluoride ions simply get left behind. Indeed, most of the outer electrons get left behind too So you get a mess of fluorine, helium, thorium (as ions) and electrons all moving in different directions.
2 points
41. ## Trying to make sense of the Fabric Of Space (The field that consists of the smallest particle-like phenomenon )

I must be missing something. Somebody arguing for the properties of the fabric of space, quotes Tesla for support, who said "... for the simple reason that it can have no properties ...".
2 points
42. ## Quick question about perpetual motion.

I'll try a logical explanation with more detail without referring to math of specific laws of physics this time: Let's say two hypothetical devices are working perpetually* as a unit without external energy source. Perpetual motion device A feeds energy (1) into device B and then device B feeds energy (2) to device A. Since no external energy is added and operation is perpetual there is no internal energy wasted; efficiency is 100%. Device A runs from the energy provided by B and B runs from the energy provided by A. Hence, over time, A must supply B with the same amount of energy that
2 points
43. ## Calculating wavelength using Lloyd mirror

But a pi phase shift will only mean half a wavelength, so multiplying by two would give me a speed of sound of 500m/s right Sorry, we have a sound transmitter with a frequency of 40 kHz and a sound receiver , with 40 cm between them. We have a sound mirror (just a steel plate) on a moving axis perpendicular to the axis of the transmitter and receiver (optical axis). As the mirror moves towards optical axis, the receiver will take measurements and show these on a graph. This gives a graph with nodes and antinodes. Now we have to calculate the speed of sound using this graph. We tried c
1 point
44. ## How to capture electrons from photoelectric effect?

To create plasma arc use Van de Graaff generator. This is from my own: Alternatively you can build Cockcroft Walton generator https://en.m.wikipedia.org/wiki/Cockcroft–Walton_generator
1 point
45. ## Inertial Drive

We know from established physics that "inertial drives" are not physically possible, hence any acceleration of the COM of the ferromagnetic ring is due to external forces; very simplified: F=ma. Note that Newton's laws exists in a framework of more fundamental theories and models developed later. Lagrange, Hamilton and Noether are specifically relevant in this case. If you believe space to be inhomogeneous or anisotropic at small scales please provide evidence.
1 point

But it wouldn’t be a perfect sphere, and the asymmetry is likely the issue here. That’s the issue, I think. The motion is radial and so is the field, and you would need a transverse component of the field to emit radiation. Which may become possible if the spherical symmetry is broken. (I have a vague recollection of an example in Griffiths of a problem where the energy of a system and the work required to assemble it are unequal, implying energy had to be lost from the system, i.e. from radiation. Can’t recall if it was this example, though)
1 point
47. ## Cryptocoins: who pays the huge energy?

Here's a Bill Maher video, totally unrigourous, humourous, on the problem. I don't think it's a particularly impressive analysis of the problem, but it highlights some of the central questions. The main points being: A) CCs are based on nothing of "real" value B) CCs exert a huge demand on energy resources I think the second point is more or less right, but the 1st one, IMO, is not. I think Warren Buffett --and Maher with him-- misses the point of what the real problem with crypto-currencies probably is. It's not that crypto-currencies have no "real" value b
1 point
48. ## The Official JOKES SECTION :)

Why is the number '6' on a clock face oriented right-side up when using Arabic numerals... ...but upside down when using Roman numerals?
1 point
49. ## Rand Paul Called Fauci a Liar

How would Fauci prove a negative? Why doesn’t Rand Paul have to present actual evidence? What is the paper he alludes to? How do we know his allegations are accurate/true?
1 point
50. ## Paradox of visual and actual positions in space.

Brief description to avoid unnecessary complication. The distance from the Earth to the Sun is about 8 light minutes, so from the Earth we see the Sun at the point in the sky where it was 8 minutes ago (in 8 minutes the Sun passes through the sky with an angular distance of slightly less than two solar disks) ... It is difficult to both explain and imagine, because most likely it is impossible, that is, cosmic distances are too exaggerated. The distance from the Earth to the Moon is about 1 light second. That is, the apparent and actual position of the moon is almost the same.
1 point
×