# All Activity

1. Today
2. ## what is the difference between speed(units of c) and the Reciprocal in special relativity? Link below for reference

I apologize for asking basic question I guess when I was originally in school either I didn't pay attention or wasn't taught properly. I assume the former but I can't be certain. I appreciate the help on basic questions. why is this wrong? Gamma = 1 / √ (1) - v^2 / c^2 = 1 / Gamma = √ 1 - v^2 c^2/ c^2 = c / Gamma = √ 1 - v^2 +v^2 = c + v / gamma = √ 1 = switch the c + v to v + c = v + c / gamma = √ 1= v + c / gamma = √ 1 = v + c gamma / gamma = √ 1 (gamma^2) = v + c -c = √ gamma^2 = v = √ gamma^2 - c or 1 / Gamma - c^2 = √ 1 - v^2 / c^2 - c^2 = 1 / Gamma - c^2 = √ 1 - v^2 = 1 + v / Gamma - c = √ 1 - v^2 + v^2 = 1 +v / Gamma - c = √ 1 =switch the 1+ v to v + 1 = v + 1 / gamma - c = √ 1= v + 1 gamma / gamma - c = √ 1 (gamma) = (v + 1) -c / - c = √ gamma -c^2 = - (v+1) = √ gamma -c^2 = -v -1 = gamma -c^2 = -v = √ gamma^2 - c^2 + 1^2 = - v / - = √ gamma^2 - c^2 + 1^2/ - = v = √ gamma^2 - c^2 + 1^2 / - = v = √ -gamma^2 + c^2 - 1^2
3. ## Supersonic sub (split from Speed limit on earth)

Why should it be for our racing submarine? Like a fish, there's no particular requirement to keeps a certain pressure inside. By all means, pressurize it if it helps. Even humans can take that so long as they don't mind the time it takes to depressurize. Similarly, given the power our sub is going to need, the buoyancy of the thing (be it positive or negative) seems a drop in the bucket compared to the sorts of forces we plan for it. Likewise, an airplane going fast need not worry about the fact that it has greater density than the air it displaces. Propulsion on the other hand is a serious issue, as it was for the early supersonic aircraft. I think fish tails would work better than a propeller, and in the worst case, we can always fall back to our rocket. Nobody said we had to sustain the speed for a long time. The shock wave is also a serious issue as you point out. The thing will be shaped like a needle, splitting the water 'gently' to the side rather than compressing it in a shock wave. Minimum sonic boom. This reduces the problem to one of the increased friction resulting from the greater surface area presented. Imagine an amoeba, injecting its skin into new territory, and then moving all its interior guts into that new expanded volume, closing it in behind. Just do that a lot faster. They have creatures that word this way. No propulsion since the skin is effectively stationary relative to the water and need not even be particularly slippery. All the motion (movement of its center of gravity) takes place internally.
4. ## Perpetual Energy?

They're actually quite common....as long as nothing is on them. ...and I'll see myself out....😄
5. Yesterday
6. ## Can science produce a utopian world?

Interesting you ask- I actually have read one book too many, Trul. I am an old scientist, with multi disciplinary background. Thats all I can say so far on the internet. I should have qualified my question as "what positive, beneficial contribution has Religion made in 3000 years". As of yet, you have not provided any answer. You did however mention education. You mean Sunday School? Where "teachers" teach how Adam and Eve were the 1st man/woman on Earth? And how Moses met God on Mt Sinai via a burning bush? Do you actually believe Religion spawned the Renaissance? Then how did we manage to produce a Galileo whos discoveries about astronomy challenged and threatened the Catholic Church DURING that Renaissance? No one can prove exactly how/what spurred on the Renaissance. Our Constitution was written mainly by Deists (Jefferson, Washington, Monroe, etc) , not exactly a religious cult (you can google it). Either way, IMO, the Constitution is not perfect, and written by at least some hypocrites, albeit, masterful writers (thing all men are created equal- except leave my slaves out of it so I alone can benefit from them). Again, I offer two of the most stark examples of the contribution of science without which, in a few short weeks you would be dead- the disinfection of water throughout the modern world and the Haber Process. There are many more examples. Religious Cult "leaders" only have offered the idea of prayer, penitence, the misguided hope of eternal salvation, and false hope. And let's not forget the vile wicked sexually disfunctional priests who pervert sexual desire/urge itself by appearing to practice abstinence as some sort of reverence to be admired.
7. ## U.S. presidential election modelling

I give him at least a pass on that one (note that this is policy not rhetoric) 2-Not particularly enamoured by the Dems either So i'm 4-2 or 2-1. I think it would be best (read least worst) if he lost just decisively enough that the decision is clear democratically. Hopefully by not so much that the Democrats see it as an endorsement of their identity politics, but that's probably not possible...if they win through the electoral college they no doubt dominate the popular vote.
8. ## how much of the outer universe can we see from where we are?

its such a pity that andromeda doesnt actually look like this to the naked eye
9. ## is it possible for large lifeforms to dominate earth in the future?

it seems that over the course of history, earths lifeforms tend to get very large before a mass extinction event happens, which reduces life back to small life forms again so, would it be reasonable to believe that earth may be headed, over the course of millions of years, back to a dinosaurlike environment again at some point in the future with large animals of some description roaming the earth, weather they be reptiles, or mammals? and the human era is possibly just one of the early phases in that process. or is there some physical reason why earth can no longer support such a thing, such as weaker atmosphere, or colder planet temperature or something to do with how the eco system has been altered by us humans which makes it impossible?
10. ## Smoke smell vs secondhand

Well I've sealed the apartment door and windows using stripping, and had brought up the issue with the board who've long since put signs up telling smokers to not smoke on the stoop (in fact the chairman said not to do so to one smoker in particular who regularly smoked at this location); but still, smokers, including at least said resident who continues to smoke there multiple times daily or close to daily, lead to whiffs of smoke smell entering my apartment, which seem to mainly enter through the front window even when it's visibly fully closed. Again, I'm not sure how much actual secondhand smoke this smell correlates with (still missing scientific studies on this) and whether the amount is significant over the longterm, but in any case I'm restricting opening of this window (for air circulation) to late night / early morning due to the smoking mainly occurring during the day and early evening, although as I said this doesn't fully prevent the smell from entering the window.
11. ## Supersonic sub (split from Speed limit on earth)

Be noisy if nothing else. Maybe if the water was kept away from the hull itself though you could avoid the worst of it. In theory if we forego keeping the interior at atmospheric pressure could streamline the hull. If crewed, atmospheric composition and depth changing would have to be taken into consideration though.
12. ## Supersonic sub (split from Speed limit on earth)

There are two types of fluid flows in aero/hydrodynamics, compressible and incompressible. They can both be modelled by little springs between each fluid particle; when you push against one particle, it pushes against the next via the little interconnecting springs, and the fluid, in effect, compresses. If you push too fast, the little springs reach maximum compression, and the particles begin to 'pile up' into a bow wave. For air, this happens at Mach 1, and the air effectively becomes incompressible. Water is nearly incompressible from the get-go ( also, liquids and solids have transverse 'sound' waves as well as longitudinal ). That's why you see a bow wave on a boat doing 10 mph. That wave is the 'shock' of the particles bunching up because they can't move out of the way fast enough. Another ( huge ) problem would be cavitation. This is usually seen in pumps/propellers where the fluid can't flow fast enough into the area behind the pump/propeller blades, creating a low pressure area ( or even vacuum ) which tends to destroy equipment. For a plane the shock is the separation where supersonic air is drastically decelerated to subsonic ( inside the shock cone ), and it carries a lot of momentum/energy which is dissipated in the 'sonic boom'. If the 'sub' was at a shallow depth, with the surface close by, the spray pattern of the water shock into the air would be extremely interesting. to say the least. So the shock wave of travelling through water would be no different than through an incompressible fluid such as supersonic air, except for the cavitation problem, which I didn't consider on Sunday ( and which may make this idea a non-starter ).
13. ## Supersonic sub (split from Speed limit on earth)

Hence my comment about the shock wave.
14. ## Does matter travel in discrete amounts of h?

"Changes" in angular momentum answers "many questions." 😎 THANK YOU... What I mean by shouldn't the electrons magnetic field inhibiting this "QM" behavior is its: Particle wave nature, among some other things I will wait on for now.. I want to make sure I get my thoughts clear on this new information and get back to you..
15. ## Spring and/or bungee cord behind vehicle?

Simplifications: I think you can ignore friction at first, since you're talking about nice rolling things. A spring on the end of a rod is easier to model than bungee, since that confines stretching to approximately a single point. The starting state is with the spring at its' resting point, everything else is rigid. And the ending state, after the acceleration is done, is a steady state where bike & car have the same velocity, with 0 acceleration. Oh, also assume the car has uniform acceleration. For the math, I'm using arbitray time dimensions (ticks; p[resumably significantly less than 1 second per tick), but that should be okay up to a scaling factor. And PS, car is much more massive than bike, bike is much more massive than spring Exact answer does require chemical or material knowledge to determine k Since you want to know about the dynamic situation between the steady states, I would assume a numerical/simulation in discrete time is necessary. Tick 0: everything has v=0, displacement of spring is 0, the car has acceleration a, everything else has acceleration 0. tick 1: car has velocity v, car has traveled distance v/2. v=at, x=0.5 at^2. The string is now stretched to length y = 0 + x. F=kx gives you the force on the spring. Assuming no kind of damping factor, the string-stretching force applies to spring & bike. F=m'a' gives you an acceleration for the bike (primes are values for the bike, unprimed is car) tick 2: car has velocity 2v, bike has velocity v', car is at position x=2a, bike is position x'=0.5 a'. Spring length is X - X'. Calculate force on spring, repeat calculation for spring force F, bike accelerationj and velocity a' and v' repeat calculations every tick, untiil car velocity and bike velocity are however close you want them to be. That's my rough draft of a procedure at least.
16. ## Perpetual Energy?

Ah, yes. Magnets not batteries. Batteries to power the electromagnets. I should proof read what I write.
17. ## Supersonic sub (split from Speed limit on earth)

Swansont, after pondering about the interesting point you mentioned, "shock waves in water", I've come to the conclusion that supersonic submarines can't be compared to supersonic aircraft. For this reason: Aircraft fly through the Earth's atmosphere - ie, through a mixture of gasses. And gasses can be readily compressed, and pushed aside. Thus generating a Mach "shock-wave" in the atmosphere. The atmosphere absorbs and dissipates the shockwave, turning it into a "sonic-boom". Which may annoy remote ground-based residents. But doesn't molest the aircraft. However - water is a different matter. Water absolutely cannot be compressed. It retains its volume no matter how much it's squeezed. This is indeed, why hydraulic machines work. Therefore, it seems to me, that if a submarine accelerated underwater at ultra-high speed, then when it reached under-water Mach -1, the outcome would be crushing disaster for the sub. Can you fault my reasoning?
18. ## Hypothetical sci-fi question about wormholes and elapsed time between the 2 points

A 'wormhole' is a shortcut through space-time, and, if used as a 'time machine', cannot get you back to a time before the wormhole was created. That being said, if the shortcut reduced a distance of 100 LY in regular space-time to one light month, it would still take you one month to traverse the wormhole. The length of the wormhole would be dependent on the topology of space-time as modified by the wormhole, and how it is 'constructed'. edit Purely theoretical, or for sci-fi, of course. I don't think wormholes are actually possible.
19. ## Consecutive values in set theory

Best way to start would be to take the time to understand relativization then.
20. ## Noisy metallic glass?

Bought a strip off eBay. Trying to figure out if it being noisier than similar strips of metal is just my imagination or not. Any help or thoughts on the subject is appreciated.
21. ## HLB Calculations

Sorry I messed up there. The equation you want is $HLB\left( {oil} \right) = \frac{{{W_A}*HLB\left( A \right) + {W_B}*HLB\left( B \right)}}{{{W_A} + {W_B}}}$ Where A refers to the first surfactant and B to the second. However the values of HLB you quote give the (not) suprising result that you require no tween at all. Are you sure you posted the correct HLB values ? Trying to look up olive oil values it looks as though your span20 value is too high, you need something below 6 The span and tween components are supposed to be chosen so their HLB values bracket the oil HLB value.
22. ## solar powered laptop

Two Broadcom distributors show up n a google search ... https://www.mouser.com/manufacturer/broadcom/ http://www.ameya360.com/mfrdetail/broadcom?utm_campaign=English&utm_medium=Google&utm_source=adwords&utm_content=guanjianzi&utm_term=Broadcom Otherwise you might try searching through eBay for used parts. The Pi 4 uses the BCM2711 4 core SoC, but that needs 4W; you might be better off with the lower power single or double core versions in earlier Pi.
23. ## Consecutive values in set theory

Oh it was different than I thought it was its funny because I see this and I think self become entity and cantors opinion was that of God so I got confused anyway im trying something that looks the same but using empty sets instead of numbers and using relativization instead of exponentialism what a confidence i added "and not all(not e)"
24. ## solar powered laptop

One way is to check what others have tied and why they are not in the market. https://en.wikipedia.org/wiki/Solar_notebook may give some hints; it is not a very good wikipedia page but the fact is that all the page's references to various manufacturers and models seems outdated and/or links are not working.
25. ## Hypothetical sci-fi question about wormholes and elapsed time between the 2 points

Hi there. I'm writing a sci-fi story for a video game. At some point in time an advanced civilization from the future, say 4010, creates a wormhole for a not so advanced civilization spacecraft in the past, say 2050, to travel through. The idea is for the not so advanced civilization spacecraft to meet the advanced one in its own time, 4010. The question is (theoretically and sci-fi speaking): how many years would have passed for the advanced civilization in 4010 until the not so advanced civilization spacecraft arrived? Its possible that I'm missing some pseudo-scientific data so feel free to complement my reasoning. I hope I made it clear. Any help is appreciated . Thank you. PR
26. ## solar powered laptop

do know where i could buy some other weak chips that could run a linux os
27. ## HLB Calculations

You need to start by finding the required HLB for the combined emulsifier. Have you done this ? - I made it 12.65
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