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If you send an email to the address listed in my about page (preferably one from an email I can verify) I'd be happy to pass on some verifiable credentials.

It's the "Spectroid" app by Carl Reinke, and it's free but I think that one's only available on Android phones. For iOS, I've heard "SpectrumView" is somewhat similar but I think has some small cost to unlock all the features. "PhyPhox" and the "Physics Toolbox Suite" can also show the audio spectrum, but they're not as specialized as the Spectroid app.

@@PhysicistMichael Thanks. Without something like that program, repeating your results might be challenging.

@@PhysicistMichael I have a problem I would like to document. I like to watch old movies on RUclips. However, I have found that in some of these movies the sound track is several tens of decibels lower than the commercial messages. I wanted to document this but my ap doesn't permit sound volume triggering or selectable sample time. Perhaps you could investigate this issue.

It's not that the star is moving in a circle, but that our reference point (the Earth, which is in orbit around the Sun) is moving in a circle. You can simulate the same effect if you hold up your thumb at arms length and then move your head in a small vertical circle. It will appear as if your thumb is moving in a circle compared to whatever objects are behind it.

Try asking the question again, this time without the lying or deceptive false premises.

Have you watched the one by Dispar's Lab? I think your free momentum is clearly visible there if you pay attention.

I have so many free momentum experiments by now, i guess i have become a master at engineering them 😂 ​@@Leksa135

Yea, I've got 1600's technology up in here!

While sunspots do still move and change over time, it's a significantly longer timescale than the convective motion around it (ruclips.net/video/icjym2uEs5Q/видео.html for a video). For how the Sun's magnetic fields affect solar weather, I've got a video here that goes into a bit of detail ( ruclips.net/video/m3eWyxyEM1g/видео.html ) but briefly, charge particles don't typically like to cross magnetic field lines (they will spiral around and along the magnetic field lines). So it's not really that the magnetic fields prevent the hot gas from rising, but that in order for convection to happen, the hot gases that have risen up need to move to the side and sink back down so new hot gas can replace it. The magnetic fields going into the Sun's surface impede that "move to the side" part (charged particles don't like crossing magnetic field lines), so it can't get out of the way for new hot material to replace it.

​@@PhysicistMichaelI still don't understand what stopping the cold gas from falling, even if gas can't move to the side , it should fall into the sunspot itself. From my perspective it looks like cold gas levitating. I couldn't see if convection in sun spot was slower , but I did notice lines of hot gas seemingly moving inwards, which is strange because why are there lines in the first place. Maybe that is where the sunpot cold gas is falling , but it falling in lines which suggest a laminar flow. The stream of hot gas seems to be moving inwards . Question are sunspots always a specific temperature, do the have range of temperature? What happens when sunspots collide?

And I try to emphasize the critical thinking and analysis skills that are hopefully applicable everywhere

Thank you for your hard work. Do you provide private tutoring to adults who love Physics by any chance ? I’m really impressed by your simple ways to explain complex phenomena.

For the cart this would be a rolling friction (depending mostly on the cart axles), but if you redid this experiment where the cart was replaced with just a block on various surfaces, you could compare the friction force results with accepted values for coefficients of friction of those surfaces.

The change in a quantity can definitely be negative if that value is decreasing (the second example I have shows a case for this). Basically this final - initial definition is used so that the change in the quantity will be positive if the value is increasing and negative if the value is decreasing. For example, let's say at the beginning of the month you have $800 in the bank, and at the end of the month you have $1000 in the bank. The change in those funds are +$200 ($1000 - $800, final - initial), and since the amount of money increased, that change is positive. On the other hand, let's say at the beginning of the month you have $1500 in the bank, and at the end of the month you have $1300, then the change in funds would be -$200 (final - initial, $1300 - $1500). That's what I mean by the change in the quantity will be positive if the value is increasing and negative if the value is decreasing, and similar consistencies hold when considering the change in vector quantities and other applications. That's why this particular definition is more useful.

@@PhysicistMichael thanks alot for answering this because whenever we talk about change we just subtract the initial value from final like it some kind of formula nobody tend to explain the logic to me ever before. It confused me alot when placing the value while practicing questions and mcqs, Specially incase when the final is -ve value and initial is +ve value_ the overall change is +ve. But the confusion is also caused because of putting wrong sign sometime. Knowing this is very helpful overall in short change can be +ve (increase) or -ve (decrease) and final value - initial value.

It really frustrates me to hear stories like this (the first part, not the last part) where certain teachers' actions (intentional or not) discourage people from a STEM education because "they're not the right type of student." Learning/understanding is primarily based on how much experience you have with the topic rather than some magical inborn ability. It's why I try to encourage introduction of math and science skills at as early an age as possible, as well as better prepare teachers to effectively introduce these topics, to help give students as much of a head start as possible. But even if someone doesn't have that early experience in STEM fields, it's never too late to get started (and teachers for all age ranges should encourage this rather than writing students off).

That's how I was originally taught as well. According to my students, this method is still alive and strong.

I'd clarify a couple points to not oversell what we can conclude from this experiment: I demonstrated the part of Newton's 2nd law that claims the net force is in the same direction as acceleration, but since I didn't measure the specific accelerations that resulted from the net force, it wasn't a full demo. I have a previous video that goes through that part in more detail: ruclips.net/video/TMlMrpztGGI/видео.html As for Newton's 3rd law, since I'm only measuring the forces acting on the hanging mass, I can't use that data alone to demonstrate the 3rd law. Newton's 3rd law always involves two forces _acting on different objects_ (the action and reaction forces). If I had a second force sensor rigidly connected to the hanging mass and use that to hook onto the other sensor (so the two sensors are pulling on each other), those two forces would always match (whether accelerating or not) and that would demonstrate the 3rd law. If you haven't seen it (and are interested) the video I made on the buoyancy force and (IMHO) an interesting example of Newton's 3rd law: ruclips.net/video/e0iGRmSwAf8/видео.html Sorry for the self promotion of other videos.

In part, yes, since Newton's 1st Law is a special case of Newton's 2nd Law.

@@PhysicistMichael Thank you for the reply Michael, never heard it said in that way, so thank you for giving something to look into and better my understanding. Very appreciated.👍😊

@@PhysicistMichael Not to split hairs to atomic levels, but doesn't Newton's 1st law talk about an object with "no forces" acting upon it rather than "zero net force"?

Just to clarify, that's not all that Newton's 1st law does. It also (indirectly) sets up the concept of an inertial reference frame, which is the condition that an observer needs to be in for Newton's laws to work. @mindlessmarbles9290 to split hairs at subatomic level, "no force" is still a special case of "zero net force"

​@@PhysicistMichael "no force" is a special case of "zero net force" but the pulley example was a situation where forces canceled out to zero net force. Anyways, I was reminded of this article: Check out ScientificAmerican "Mistranslation of newtons first law discovered after nearly 300 years." (Apologies if I'm being annoying.)

That would likely be an improvement (and I encourage anyone interested to replicate these experiments, especially if they can improve on the methods). I would warn that you'd probably need to do some fine tuned experimenting with the motor since the needed output torque varies during the initial acceleration and coasting phases. The other difficulty I noticed with this (and in similar experiments), is that during the changes in motion (accelerating to coasting and back), I was getting some vibrations in the string which seemed to cause some of the fluctuations in the force data. Since I had long enough coasting phases to highlight averages over multiple fluctuations when measuring the tension, that wasn't a major problem, but those same fluctuations could be a problem getting the motor to pull at a constant speed during the coasting. Just some thoughts if you do end up trying this.

Glad it's helpful! As I mention near the end, this style of question (comparing the strengths of forces if the object is moving in a certain way or vice versa) shows up in a lot of intro physics courses. Might be a different kind of case (I mention a jet where the engines apply a forward force and air resistance pushes backwards, or could be pushing a crate across the ground where you push forwards and friction pushes backwards, or a skydiver falling with gravity pulling down and air resistance pushing up, etc.) but we can approach all these cases with very similar methods.

@@PhysicistMichael many time when I use the formula to get the answer I get it but feel unsatisfied due to the lack of understanding of the concept and demonstration- the way science is taught these days is understable as not all the experiment can be performed or recreated in the classroom for the students. leading to science been taught from book and student not understanding it but just memorizing it- even if u show the experiment and not data for me that is more than enough but here you literally compared it like science practical book that is amazing

I think it’s impossible to not, I think the subjective “intuitive” experience is kinda the wheel that determines which scientific road we go down as humanity out of an infinite potential number of roads. Kinda like the problem of induction, there isn’t really a non-circular way to justify the foundations of every belief you have, it has to be arbitrary. But funnily enough, that’s why I think Copenhagen is “intuitively” more correct than many worlds. The only thing we can know the most the most intimately is our consciousness, our own sense of choice, of one aspect of reality existing over the other, choosing one decision over another. That sense of “choice,” of there being a bunch of potentials but only one actual, seems more intuitive as to how the universe works based on my experience of the universe. But really there’s no good proof either way, only subjective thoughts.

I partially agree with @mattm8314 that you can't completely escape intuition, it's part of our psychology. This is part of the point I wanted to make in the video, to try to train your intuition to steer you towards using methods that have more demonstrated reliability rather than any individual conclusions. I'm going to answer a slightly different question, instead of which ideas I give higher credence, where I would recommend investing time and resources in these different areas of science. In "The Black Swan" (I mention this book in the video and description and highly recommend it), the author is a former hedge fund manager and made a fortune by betting on those "black swan" events; very rare but extremely impactful events that other investors models failed to properly account for. Basically, over time you'd lose a bit, lose a bit, lose a bit, and then that black swan event would hit and make a huge amount. This is in contrast to other investors strategies that didn't know they were in danger of these same black swan events, and would make a bit, make a bit, make a bit, and then get wiped out in a sudden unexpected crash (if you've seen the movie "The Big Short", it's kind of like that but more general). Note, that this is not suggesting the lottery is a good idea (the statistical models in that are reliable and virtually guarantee loss). His general recommendation for investing (my understanding of it at least) is keep a large base amount in safe and stable investments so you can’t go bust completely, and then spread smaller investments across a variety of higher risk, higher reward options. Some of those might go bust, but if you have an unexpected good event if one of your picks is the next Microsoft or Apple. Why am I talking about this? Because I think investigating sciences in general should follow a similar pattern. 1) keep a strong base of investment in developing fundamental technologies (better computer systems, material science, mathematical methods, etc.) and then 2) spread smaller investments in a wide range of higher risk/higher reward (like competing hypotheses on QM interpretations, early Universe cosmology models, beyond standard model theories, etc.) That base investment will always have a positive payoff (and develop the technology to fuel better experiments and observations that might distinguish between competing high risk ventures). As for the high risk ventures themselves, yes, some will go bust (though they can still make great contributions to side fields on the way), but that’s why we support multiple approaches, so it’s not putting all our eggs in one basket. Sorry about the rant, but hopefully there’s something interesting to think about in all that.

@@PhysicistMichael very interesting concept comparing this to investment strategies! Not sure if this is what you’re referring to, but to me it seems like a tie to algorithmic learning / existing at the edge of chaos for a complex adaptive system; there exists a balance of stable, predictable systems that maintain longterm stability which dynamically interplay with chaotic, unpredictable systems which maximize system flexibility, adaptability, and growth. On a different side of things, do you see the process of science as a pyramid in which the fundamentals naturally lead to universal higher-level concepts? Or do you see science as an objective tool which guides the development of a subjective experience? In other words, if at some point we’re able to observe alien life that’s followed a similar technological growth model as humans, would our technological developments and fundamental scientific concepts be more similar than they are different? Or would they entirely be a product of the evolution of the culture that uses them? Kinda like a butterfly-effect look at science versus a discover/deterministic look at science, were we always destined to develop nuclear energy (or whatever concept) as a step towards scientific understanding, or was that just a quirk of our technological evolutionary development? Is science an external system to be discovered or a subjective process by which we make things useful to our evolutionary development? Are we “unearthing” scientific discoveries or are we creating them?

@@PhysicistMichael not a rant at all, you make very good points. I agree with you on the need to invest heavily in fundamental technologies. I’m thrilled to witness the increased global awareness and investment in fundamental sciences, especially foundations of Physics and the origin of the universe. I wonder what your thoughts are about why there was high resistance or lack of interest amongst physicists back in the day and maybe even some up until now in the curious understanding of QM in a fundamental way ? There « shut up and calculate » framework… I’d use my intuition here and lean towards thinking that scientists, in general, are curious… is it fear of the unknown? Or discomfort with the « spookiness » of QM? I’d appreciate your thoughts, and thank you.

​@@NalitaQubit When I was in undergrad taking QM courses, there was a professor (who I ended up doing some research projects with) that in his own cohort the general feeling was "interpretations of quantum mechanics is where careers go to die." He's since done some work in this field so clearly didn't agree with this so he clearly didn't agree with that assessment. I think historically it was probably a combination of a fairly long dry period where there just wasn't a lot of notable progress in the field, as well as the "shut up and calculate" working quite well for all the experimental data that was available at the time. If the calculations run the same and match predictions, is a potentially unfalsifiable interpretation going to add anything? The big question is whether a specific interpretation leads to _new_ predictions that can then be put to the test, and for some of the proposed interpretations of QM it can be a hard question to answer. It's also important to remember that (most of) the big advances in science come when we disprove our ideas; when a current model runs into a situation where it disagrees with experiment. When this happens it helps narrow down what directions we should start to look in for improved models, rather than just adding new things into new models (nearly at random). One could argue this has been happening the past few decades with particle physics... we haven't found much in the way of confirmed deviations from the standard model of particle physics, so the host of models beyond the standard model are somewhat firing blindly. When I was in undergrad talking to professor about research projects, shortly before the LHC came online, I remember a different professor telling me I should go into particle physics because (this isn't an exact quote) "now's the time to make a new model with some new features and throw it into the ring; maybe it'll win." Even at the time I wasn't really impressed with this scattershot method of approaching physics. Might have deviated again from your original question, but hopefully it's still somewhat interesting.

Thank you for the kind words. I'm trying to expand this series, the testing physics series, and the physics primer series (which is why it'll probably be a while before I get to some of the other topics that you've recommended). I really like the AI in astrophysics idea. I've added that to my list of topics to cover in this series.

Really do appreciate the kind words. Thanks!

I agree that there is an additional level of complexity in analyzing questions where the choice of inertial frames of reference come into play. For example, how much kinetic energy an object has depends on your frame of reference. However, the principle of conservation of energy will hold in all inertial frames of reference (see my videos on relative KE measurements ruclips.net/video/CfNGff-jNpE/видео.html and rockets in different reference frames ruclips.net/video/lf2_6wXPQiU/видео.html for some examples of this). For your example of the rotating person holding the mass, then if we're not including the spin up or spin down portion (just when they're spinning at a constant rate), the person standing next to them _would still say no work is being done_ . The person holding the mass would be applying a force with two components, upwards (balancing out the gravitational force) and inwards (towards the center of the circle, allowing for the centripetal motion). But if they're not speeding up or slowing down then there would be no force acting along the tangential direction of motion, and for the definition of work we need a component of force parallel to the direction of the displacement. Compare this to if I had a cylindrical container that had perfectly frictionless walls and floor, and I took a mass on the outer edge of the container and gave it a push. If everything is perfectly frictionless, that mass would keep sliding around the outer wall forever, and never change (again, no friction or air resistance to cause it to lose KE and generate heat). The wall continually pushes inwards on the mass, allowing the centripetal motion, and the floor continually pushes upwards, balancing the gravitational force. Are either of these forces adding energy to the mass? If so, where is this energy coming from? If not, how is the motion of this mass distinguishable from the case of me holding the mass and spinning it in a circle at a constant rate? For your accelerated rocket example, (which is a non-inertial frame so we need to be extra careful here), I would agree that work is being done on the mass as I hold it stationary and its kinetic energy, from the point of view of someone watching on the sidelines, is increasing, _but that energy is not coming from the use of my muscles_ . Imagine again that instead of me holding the object with my hand, we hung it from a string inside the rocket. As the rocket keeps going, nothing is changing with the string (it's also gaining a tiny bit of KE as the rocket accelerates, but we'll assume the string is nearly massless). The energy that the mass is gaining is not coming from the string (or your muscles in the case of holding it) but from part of the energy output from the rocket. In both cases (holding with hand or string), if the rocket turns off, that mass stops accelerating and stops gaining KE. You can also analyze this system in terms of looking at the person + the mass they are holding. Standing on the floor of the ship, there will be an upward force of the floor pushing on the person's feet acting over a certain distance. That force must be great enough to accelerate BOTH the person and the mass they're holding. If we then look at just the person, they've got the force of the floor pushing up on them, but if they're holding the mass, by Newton's 3rd law, if they're pushing up on the mass, the mass is pushing down on them. The downward force of the mass on the person, acting over that same distance would do negative work on the person (removing some of the energy from the person that was originally provided by the floor pushing up on them), exactly matching the positive work done on the mass by the person pushing up on the mass (that energy goes towards the mass). But again, you could replace the person and their muscles with any other rigid support structure and repeat this exact same analysis. Hope that's at least somewhat clear, but let me know if you have follow up questions/critiques.

@@PhysicistMichael In the example of the rotating person holding the mass, I’m not talking about a vertical force. The object is being moved in a circular path parallel to the ground about the head-to-toe axis of the person. The circumference about this axis is the distance in the work = force x distance equation. Let’s say it’s a long weight that touches the floor and I can only drag it around. If I drag the weight in one direction, we certainly call that work and calculate it by the force x straight line distance. Now imagine me dragging that same weight in rotation about my head-to-toe axis. All that distance the dragged weight is moved counts as work, correct? In the accelerated rocket example, I was careful to clearly say that work is done on the weight, which I believe is what you focused on in the video. It’s irrelevant to the example, whether you say the rocket does the work or my muscles do the work or some combination of the two. The fact is that all outside inertial observers will say that work is being done on the weight. And this is equivalent to someone standing on the Earth holding the same weight.

First paragraph - I agree if you pull an object in one direction and it moves in that direction, work is done. But that's not what's happening in the rotating case. Once you're up to speed, there would be no force acting in the direction tangential to the object's path, only a force pulling inwards towards the center of the circle. That inward force would always be perpendicular to the direction of motion, so no work is done. That's part of the point I was trying to make by replacing the person pulling with mass sliding without friction on the edge of the cylindrical container. If there's no friction, the contact force from the wall can only push straight out of the wall (inwards towards the center of the circle in this case), which allows the rotation motion, but since that force is always perpendicular to the direction of motion, that force is not doing any work. Work = force x distance x cos (angle between those two vectors), and in these cases the angle between those two vectors would be 90 degrees, which results in the work being zero. When we are getting the rotation started there would be some forces in that tangential direction and some work would be done, but not once we get to the constant rotation phase. For the second question of changing the reference frame to another inertial frame; first, the work done by specific forces on specific parts of the system will depend on the frame of reference (just like KE of an object depends on the frame of reference). However, the concept of conservation of energy applied to an entire system will hold in any frame of reference. Let me give a different example, one that hopefully still addresses your concern and avoids the issues with jumping into general relativity problems (where if we use the non-relativistic approach then the two systems are not both inertial, and if we use relativity, the definitions that we use for work and other quantities need to be significantly modified). I don't want this to be taken as a dodge, so please let me know if there's a critical point that is missing from here. Consider Alice pushing horizontally against a giant boulder where the boulder doesn't move. Bob is standing on the ground beside Alice and says "Look, the boulder isn't moving, so no work is being done on the boulder despite the exertion that Alice is feeling". Let's say you, Tim, are in a spacecraft off the Earth and traveling inertially parallel to the ground. From your perspective you say "In my reference frame the boulder is moving as Alice applies her force, and those directions line up as well, therefore Alice is doing work on the boulder." (I hope I'm not straw-manning you, this is my interpretation of the third paragraph of your original comment, please correct me if I'm wrong with this interpretation). But look again at the boulder. The applied force from Alice was not the only force acting on the boulder. In order for it not to move, there would need to be a frictional force pointing backwards that exactly cancels the force from Alice. So in your frame of reference, yes, there is work done on the boulder by Alice, but there is exactly an opposite amount of work being done on the boulder by friction (negative, so overall no net work done on the boulder), so the boulder does not gain or lose any KE itself. Additionally, in order to keep Alice from sliding backwards (in your reference frame) the friction on her feet must be pointing forward (in the direction of motion) so the work done by friction on her would be positive, and the force of the boulder pushing back on her would be negative, again in a way that balances out. Same thing for the ground that Alice and the boulder are in contact with. For all three of these objects (Alice, the boulder, and the ground) the net work done is zero, since the net forces are all zero. But what does that mean about the chemical energy being used by Alice's muscles? It doesn't go into the boulder, it's just dissipated as heat, regardless of the reference frame (at least in the static case) There were two points I wanted to make with this part of the video. First, based on how our muscles work, we have this trained bias that suggests that if we're applying a force and getting tired, we must be transferring energy from our muscles to the object we're holding. This is not the case, as demonstrated by any of the cases of switching out the human with any static support structure. Even though we are using chemical energy, heating up, and getting tired, that energy is not necessarily going to the object. Second, and much more importantly, we need to avoid relying on our intuitive gut reaction responses because they can be flawed and instead on arguments backed by evidence (which we've both attempted to do in this exchange; neither of us said "I just think this is the case"). This was longer than I thought it would be... maybe worth its own video to go into the details for, but let me know your thoughts.

@@PhysicistMichael Appreciate the detailed response; I’ll try to hit on most of the main points. First paragraph - I’m not in agreement here. It seems like you are maybe thinking of it like the object is in orbit, but hard for me to tell so I’ll try to make the example more concrete. There is a mannequin laying on the ground and I grab it by the hair and start dragging it such that the torso and legs are touching the ground (I don’t think touching the ground is necessary but helps to visualize the point). If I drag it in a straight line, that is work. If I drag it in a meandering curving path, it is work, but you don’t just calculate the work to be the force times the straight line start and end positions. You have to include all the meandering as that was also work. And if I rotate my body and keep dragging the mannequin in a circle around myself, all that distance for the path of those circles is work. If you disagree with this, we will just have to agree to disagree on this point. If you agree up until now, then let’s address your comment about friction. Why would this be a frictionless environment? No one said we were doing this on frictionless ice or out in space. Let’s drag the mannequin on a sandy beach. There is obviously friction here on Earth, so I don’t understand why you think appeal to zero friction applies in an example about work. That would be like you claiming that dragging the mannequin in a straight line is work done in an amount equal to the force x distance, and me saying no that’s not work after you get the dragging started because there is no friction out in space. It’s a true point, but it just doesn’t apply here on Earth with this rotating example we are using. Your 2nd paragraph - I’m not an expert on conservation of energy, but it doesn’t seem very applicable here. The total KE of a system will be different depending on the reference frame. For example, if I take off in a rocket ship and begin traveling inertially at 1/2c, the KE I would compute for all objects in the solar system would be wildly higher than the KE you would compute assuming you remained on Earth. If you are saying there is conservation of energy within a reference frame, I agree of course, but I’m not understanding how that applies to this discussion about work being dependent on the reference frame. For the rest of your response, the only thing that I think is a bit of straw man is that I’m being clear not to make a claim as to who or what is doing the work. So no, I wouldn’t say “therefore Alice is doing work on the boulder”, but rather “work is being done on the boulder”. But I can tell you are responding in good faith. My point is just that any claim that work is being done on something is dependent on inertial frames because distance depends on the coordinate grid of each particular inertial reference frame. I don’t think we really disagree here, and to the extent we do, I think much of it comes down to work being an archaic concept that really isn’t too useful outside of answering simple questions on high school physics exams. In cosmology for example, I don’t see anyone talking about work because it’s not a good concept there (even though there are formulas for work done by gravity and for work done by gravity in space). And similarly, applying the concept to other inertial frames is sort of outside the concept’s useful scope in my opinion.

@@timjohnson3913 Thanks for the clarification. I think we're in general agreement on most points. Point 1: With the mannequin example, I agree that dragging it along a curving path, you're going to need to include the details of all the meandering curves (for each part, take the force x each little bit of distance x the cosine of the angle between those vectors, and add up (integrate) over all the little bits of the path) and that this will not be the same as just looking at the straight line distance from start to finish. The system I thought you were referring to would be like a tetherball on a string, and in that case the force of tension on the tetherball and the direction of motion would always be perpendicular, so the cosine(angle) term in the work equation would give zero in that kind of situation. This is also why I was picking an example with no friction to highlight that the system would keep moving at a constant speed (not gaining or losing any KE) even though a force is being applied. The presence of friction wouldn't change that if the other applied forces are perpendicular to the direction of motion, than those forces still wouldn't be doing work. Point 2: So we agree that there is conservation of energy in a reference frame. A part of conservation of energy is that the net work done on an object will match its change in KE. So let's say that in one reference frame, a force is applied to an object as it moves a certain distance, and let's say the speed goes from 0m/s to 5m/s. In another reference frame moving backwards at 10m/s, they'd see the same object going from 10m/s to 15m/s. That associated change in KE will be different (since KE depends on v^2) and the work done will also be different (since in the other reference frame the distance over which the force is applied will be different), but they'll still match via conservation of energy. Those are the ideas I was trying to connect. Point 3: If you're not referring to the work done by a particular force, then are you referring to the net work done? Because in the boulder case, if the net force is zero, it'll be zero in any inertial frame so the net work will always be zero. If the net force is not zero than you will get different amounts of net work done in different reference frames. As for work being an archaic concept, I'd agree that calculating the work directly isn't often needed, but it's still a major underpinning of a lot of newer methods. Using the work equation is how we calculate the change in potential energy for conservative forces (very widely useful) and the work done by gases shows up in the first law of thermodynamics (in early universe cosmology it's generally approximated that thermodynamic processes are adiabatic, which means there's no heat transfers happening and the work done on a volume of gas will match the change in internal energy). So while we don't often use it directly, the equations we do use include it as part of their derivation. BTW, I appreciate that we can both recognize that we're both having this discussion in good faith. It doesn't always happen that way in comments, so thank you.

Perhaps some would think, if we had enough boxes containing compressed springs dotted around our homes, there would be no need to put the heating on. 😂👍

I agree that would be an equivalent example

Sounds like hysteresis.

The testing physics video I'm putting together for next week will address part of this (looking at misconceptions/common problems with intuition on forces acting on stationary and moving objects). This is why someone giving reasons is still just another claim until those points are actually demonstrated (evidence), and intuition isn't a demonstration.

​@@PhysicistMichaelwell clearly you're trusting your intuition saying the lever is using angular momentum when clearly the object holding the lever up is stationary. No? Isn't it just a conversion and you're making the excuse because you don't believe force is traveling at the speed of light? Momentum would measure propulsion of the two masses better. Like newton firing cannon balls off the top of the highest mountain. It's ridiculous. You're brainwashed for that. I'm not against Ian doing experiments tho but please. Nice try. Brainwashed. ❤

​@@PhysicistMichaelyou need G to know what the weight is obviously and it always has to go up in an experiment to compensate for the deceleration when the ulterior object like the lever will push down because it has to because G is conserved in an isolated experiment.

​@@UnescapableTortureIa Iam afraid your arguments are making no sense, I can't understand you, are you another death cult member?

I agree with first point about extremes of where we set our levels of confidence in a claim (made a similar point myself in my Claims vs Evidence video). I try to take the approach of Hume, to proportion my confidence in a claim to the strength of the evidence. This avoids the all or nothing approach in accepting a claim. If there's only weak evidence, then I'll have stronger doubts. If there's stronger evidence, I'll have more confidence, but not complete confidence (always subject to revision given new data). And if there is no evidence, then I do not accept the claim (although this does not mean I accept the negation of that claim; just because I'm not convinced that Bigfoot exists (because I haven't seen any good evidence) does not mean that I'm convinced that there couldn't be some undiscovered primate species) As for what scientific discoveries we'll make in the next few centuries... would be cool to see, but as an educator my response is "why wait?" Those discoveries will only happen if we (as a society) are willing to invest the resources (time, money, material, and brainpower) to make it happen, so let's get to work! Thanks for the comment!

Happy new year to you as well!

I've updated the description for you and the others who have pointed this out over the last decade. Thank you for your service.

Can you point to any actual experiment (not just the thought experiments where the outcome is asserted, but one where clear quantitative measurements are taken and analyzed) where 1) DS's claims predict a different outcome from that of textbook physics principles and 2) the outcome matches DS's claims? If so, please provide a link with the details. If not, why would you put a high confidence in DS's claims over that of textbook physics. The experiments I've gone through (over a dozen different ones now, with many different trials in each) have all _demonstrated_ a match with textbook physics to a reasonably high accuracy (commensurate with the limitations of the measurement tools I've used in each). If the textbook model is wrong, and DS is right, it seems like your options a) or b) would need to be true for every single trial of every one of those experiments... but it seems to me incredibly unlikely that all of the flaws or missing assumptions would somehow consistently lead to results that accurately match the textbook physics models. So, am I (and millions of other scientists that have done these experiments) just super lucky? Or am I (and those same other scientists) all part of a global conspiracy for... reasons? Or are DS's claims maybe not quite as reliable as you seem to think? Again, bring data if you want me to take your claims seriously. Otherwise my feelings towards this conversation are not ones of hurt, but of boredom.

Glad you appreciate them. Maybe the reach of these videos will increase in time; in algorithm we trust.

I think that I was having momentary difficulty thinking of an adjective for the lower cost meters that acknowledged their limited functionality in a way that didn't come across as talking smack

@@PhysicistMichael Ahh, in the UK we would refer to such things as, cheap and cheerful! Thanks for your reply Michael. Hope you had a good Christmas and all the best for 2024.👍😊

I talk about these a little bit in some videos near the end of this series, more about the large categories of potential explanations than the small details, because right now we don't really have any data to specifically test and distinguish between different varieties of WIMPs/Axions. There's been some recent work (past six months or so) severely limiting some of the modified gravity models, but not so much for dark matter particle candidates.