1

Physics, Astronomy & Cosmology / Re: Who is the author of the theory of tidal barycenter?

« on: Yesterday at 21:33:53 »

I agree to 90%

Then you're 10% wrong.

2

Physiology & Medicine / Re: Is sexual pleasure caused by evolutionary genetics?

« on: 27/07/2018 17:43:48 »

All of our functions are the result of evolution, so yes.

3

General Science / Re: Are the laws of physics unstable?

« on: 16/07/2018 20:49:15 »

I've heard of these kinds of things before. The world is full of reports of the strange. Although I wouldn't rule out the possibility of anomalous events happening, we would need some kind of solid evidence that these events do indeed occur before the scientific community as a whole would accept it. The problem in this case is that we only have the word of a few witnesses to go by and we don't know the character of these witnesses. People can and do produce hoaxes, unfortunately. I'm not saying that they are necessarily lying, just that you should always take extreme claims with a grain of salt until good supporting evidence comes along.

4

Physics, Astronomy & Cosmology / Re: Can you explain how to heat and cool using magnetic fields?

« on: 14/07/2018 00:51:41 »

So why bother?

There are definitely some advantages, such as safety and convenience. For applications like inductive cooking, it's significantly safer than hooking wires up to a metal pan and then trying to fry an egg with it. It's also easier to do if all you have to do is put the object you want heated into the field instead of trying to find somewhere to attach electrodes to it. I'm guessing that the heating is also more evenly distributed throughout the material via magnetic induction.

5

Physics, Astronomy & Cosmology / Re: Can you explain how to heat and cool using magnetic fields?

« on: 13/07/2018 23:30:52 »

I had not heard about using magnetic fields to cool things before, but heating objects up with them is pretty easy and commonplace (inductive cooking, for example). You can look into that here: https://en.wikipedia.org/wiki/Induction_heating

Here is a video displaying magnetic induction heating a metal to white-hot temperatures, causing it to melt:

6

Physics, Astronomy & Cosmology / Re: Does a photon have true zero mass?

« on: 06/07/2018 23:42:35 »

I'm pretty sure that any method we know of to measure mass would indicate that photons do have mass. They are pulled by the gravitational field of the Sun, so Newton's third law dictates that they must also be pulling on the Sun as well. You can't weigh a photon on a scale normally, but I'm pretty sure that what we know of physics indicates that a hollow sphere made of perfectly-reflective material would become heavier when placed on a scale if you had a lot of high energy photons bouncing around inside of it.

The difference between a photon and a particle like an electron is that there is no minimum mass that a photon can have. It can have an arbitrarily low mass that is related to its energy. Electrons, on the other hand, have a finite mass (0.511 MeV) even when they are practically motionless.

7

Guest Book / Re: Discussion on spams, ad posts, and other bad user-generated content.

« on: 04/07/2018 05:44:42 »

I was thinking of a possible measure to help cull the spam on here. There seems to be a recent outbreak of new users posting over a dozen new topics at a time filled with nonsensical messages. Perhaps it would be possible to reprogram the discussion board to limit the number of threads that a new user can create per day until they reach a certain post count?

8

New Theories / Re: How cloesly does a new thoery have to come to old theory?

« on: 02/07/2018 18:45:42 »

There is no requirement for a new theory to bear any particular degree of similarity to the old theory it is attempting to replace. It just needs to explain the existing data better than the old theory does and, more importantly, to be falsifiable and to have survived being falsified by critical experimentation. Reproducibility of those experimental results by independent groups is also important as is the statistical significance of those results.

9

General Science / Re: What are the leading technological and social challenges that need addressing?

« on: 02/07/2018 05:08:40 »

You are being quite harsh.

Perhaps, but don't let it crush your enthusiasm. I had similar such inventive tendencies when I was younger (and sometimes do still get ideas once in a while). Keep working at it and you might come up with something useful some day.

10

General Science / Re: What are the energy harvesting methods from movements?

« on: 02/07/2018 04:53:48 »

Sadly, those shake lights are pretty inefficient: https://www.electronicsweekly.com/made-by-monkeys/electricalelectronics/flashlight-has-dismal-light-ou-1-2007-06/

If you know the mass of what is moving and how fast it is moving, you can easily calculate how much kinetic energy it has by using the equation E_k = (0.5)mv², where E_k is the kinetic energy (in joules), m is the mass (in kilograms) and v is the velocity (in meters per second). The power you get will depend on how fast you can extract that energy (remember, 1 joule per second equals 1 watt). Of course, you'll also have to consider inefficiencies that will prevent you from accessing 100% of that energy. This article lists various efficiencies of different kinds of energy conversion methods: https://en.wikipedia.org/wiki/Energy_conversion_efficiency#Example_of_energy_conversion_efficiency

11

Just Chat! / Re: Human corpses as biomass?

« on: 02/07/2018 02:13:57 »

I was thinking not to burn the corpses but to feed bacteria or something to produce biofuel. 35 tonnes of bacteria food every day would sustain a huge bioreactor.

Then the total energy yielded will be less than in my original calculation. Every time you add an extra step in converting energy from one form to another, you end up with inevitable waste heat. There are also combustible substances in the human body that can't be converted into substances like ethanol, so that's another source of energy loss.

An average estimate for the human body would be a content of 5% carbohydrates: http://www.volac.com/lifestyle-ingredients/why-whey/market-sectors/protein-and-the-human-body . If the total mass of the corpses is 120,000 kilograms, then the amount of carbohydrates would be 6,000 kilograms. During typical fermentation processes, you get about 0.511 grams of ethanol per gram of glucose. That's 3,066 kilograms of ethanol (about 1,026.5 gallons). Since the specific energy of ethanol is 30 megajoules per kilogram, that is 91,980,000,000 joules per day of ethanol.

12

Just Chat! / Re: Human corpses as biomass?

« on: 01/07/2018 18:00:03 »

To do a quick calculation, I'll use this estimate of 110,000 kilocalories for an average human: https://www.quora.com/How-many-calories-are-in-a-human-body

Admittedly, this is probably a slight underestimate, since indigestible things like hair and fingernails could potentially be burned to release some energy as well. I'll ignore that for the time being. 110,000 kilocalories times 1,600 people is 176,000,000 kilocalories. There are 4,184 joules in a kilocalorie, so 176,000,000 kilocalories times 4,184 is 736,384,000,000 joules per day. There are 86,400 seconds in a day, so 736,384,000,000 joules divided by 86,400 is 8,522,962.96296 joules per second (about 8.5 megawatts).

That's not a lot of energy compared with many power stations, which usually run from hundreds of megawatts to multiple gigawatts. It is more, however, than a typical wave power plant and a few tidal power plants. See this list: https://en.wikipedia.org/wiki/List_of_largest_power_stations

Like Bored Chemist says, gathering the bodies would pose an important obstacle. Delivering bodies from around the country to a power station will require burning large amounts of petroleum products in order to power the vehicles (unless you used solar-powered cars or something, which have their own issues). If you burn more energy transporting the bodies than you get from burning the bodies, that would render the point moot. I may look into calculating that fuel burn later.

13

Cells, Microbes & Viruses / Re: Can Life Exist without Oxygen?

« on: 01/07/2018 15:01:37 »

BUT keeping aside Oxygen(O2) and stretching the question further as to could life generate, survive & exist without any Oxides at all???

Given that water is an oxide, the answer appears to be no. For Earth-based life at least.

14

Science Experiments / Re: Resonant effects & few questions, if you hv facility pls do these experiments...

« on: 28/06/2018 06:27:38 »

Resonance is a term with a very broad meaning. If you are talking about destroying complex structures by vibrating them, the frequency needed is going to vary widely depending on the specific characteristics of that structure. Knowing what it is made of will not be enough on its own. Its dimensions and shape will play important roles as well. Remember, bells of different sizes all made of the same material will still have different vibrational frequencies.

If you are asking about molecular bond vibrational frequencies, this may be useful to you: https://en.wikipedia.org/wiki/Infrared_spectroscopy

15

Question of the Week / Re: QotW - 18.06.24 - Why do people get bored?

« on: 25/06/2018 22:08:37 »

You can see potential advantages by comparing two tribes of primitive humans: one that can become bored and one that cannot. The bore-proof tribe would be content with putting the minimal effort into maintaining their basic needs. They would be less likely to explore new places or come up with novel ideas. They would be prone to stagnation and perhaps also become less likely to develop new skills and hobbies that could be useful in the future.

The bored tribe would be more likely to explore, increasing their likelihood of finding better hunting and foraging grounds. This would also increase their total knowledge of their land, which is something useful to teach new generations. Spending time developing new skills to stave off boredom would also make them better prepared to changing conditions. So there are some obvious advantages to boredom when it comes to an intelligent, social species.

16

Physiology & Medicine / Re: What do Caucasians see in their peripheral vision, and how is their visual field

« on: 17/06/2018 03:26:37 »

This is something that I haven't thought about before. I feel fairly qualified to answer as I, admittedly, have a pretty big nose. I can definitely see both sides of it when I try to, including the nostrils and the bridge. I can also see the curve where it blends into the brow ridge and I can see my eyebrows as well. However, doing that requires effort and these aren't things that I see when I'm looking around under most circumstances. I've never thought about it limiting my field of vision.

17

Plant Sciences, Zoology & Evolution / Re: Could a blue whale fly?

« on: 24/05/2018 22:22:42 »

Wing flap rate is more difficult to calculate. This article describes an equation that can be used to estimate it: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.530.7390&rep=rep1&type=pdf

f = 1.08(m^(1/3)g^(1/2)b^-1S^(-1/4)ρ^(-1/3)), where

f = wing beat frequency (in beats per second)
m = mass (in kilograms)
g = force of gravity (in meters per second squared)
b = wing span (in meters)
S = wing area (in square meters)
ρ = air density (in kilograms per cubic meter)

Unfortunately, we don't know the wing area for this hypothetical flying blue whale. I'll look around to see if any equations are available to help predict it.

EDIT: I found what I was looking for. It's in the very last page of this artlcle: https://ocw.mit.edu/courses/materials-science-and-engineering/3-a26-freshman-seminar-the-nature-of-engineering-fall-2005/projects/flght_of_brdv2ed.pdf

By using the graph, I estimated that the needed wing loading for an average blue whale is between 151 and 232 kilograms per square meter. This corresponds to wing areas of 301 and 588 square meters. Now let's go back to the original equation. For the 100,000-pound (45,500-kilogram) blue whale at sea level, this yields:

f = 1.08(m^(1/3)g^(1/2)b^(-1)S^(-1/4)ρ^(-1/3))
f = 1.08(((45,500 kg)^(1/3))((9.8 m/s^2)(1/2))((34.08 m)^(-1))((301 m²)^(-1/4))((1.225 kg/m³)^(-1/3))
f = 1.08((35.7)(3.13)(0.0293)(0.24)(0.9346))
f = 0.793 beats per second (47.58 beats per minute)

18

Question of the Week / Re: QotW - 18.05.21 - Could we eat an alien?

« on: 22/05/2018 00:34:23 »

That depends on how similar we are to them. They would need to be sufficiently similar to us biochemically in order for our enzymes to break down whatever their tissues are made of. Even being carbon-based wouldn't be enough of a guarantee. They might, for example, be composed of molecules that are the chiral mirror of our own. Our enzymes would have trouble with those.

19

Physics, Astronomy & Cosmology / Re: Undiscovered energy that could explain dark matter?

« on: 21/05/2018 02:32:55 »

In a sense, yes. Even modelling dark matter as massive particles still means that those particles have an energy associated with their mass.

20

Physics, Astronomy & Cosmology / Re: Does light have a weight?

« on: 20/05/2018 07:29:35 »

then am I way off base asking what effect light has 4.24 light years away from an object,  over millions of years,  multiplied by trillions of stars,  combined with the process repeating for billions of years with new stars replacing dying stars? 4.24 ly is distance to nearest star.  granted,  each photons effect is negligible,  but the accumulated effect must amount to something.  if we can see a photon,  then it must affect an object,  however miniscule.  surely this must add up to a phenomenal amount of "light pressure"........ and if light has mass as some theorize,  could this be the missing mass needed to make the models of the universe work correctly?  ..........perhaps this material is not so dark after all. .....

I'll see what I can come up with calculation-wise, but first I'd like to point out that (as shown by E=mc²) that energy already has an associated mass and therefore a gravitational field all its own. I'm sure scientists would have taken into consideration this fact when calculating how galaxy rotation curves should look. The anomaly remains.

Just for fun, let's see how much radiation pressure Proxima Centauri exerts on Earth. The power flux of the Sun at 1 AU is 1,360.8 watts per square meter. Proxima Centauri has a bolometric (total) luminosity of only 0.0017 times that of the Sun, resulting in a power flux of 2.31336 watts per square meter 1 AU away from it. Proxima Centauri is 4.246 light-years away, which is equal to 268,521.61 AU. Using the inverse-square law:

1/(268,521.61)² = 1/(72,103,855,037) = 1.3868884 x 10^-11

Multiply this by the power flux:

(1.3868884 x 10^-11)(2.31336) = 3.2083721 x 10^-11 watts per square meter

There are two different pressure equations that could be used now: one that assumes all the light is absorbed and one that assumes all the light is reflected. Reflecting all of the light doubles pressure. Earth, however, neither absorbs nor reflects all electromagnetic radiation. So instead, I will assume that the Earth reflects 30.6% of all radiation back into space (based on its bond albedo of 0.306). So to put that into equation form:

P = ((1.306)(I))/c
P = ((1.306)(3.2083721 x 10^-11))/299,792,458
P = 4.190134 x 10^-11/299,792,458
P = 1.3976783 x 10^-19 pascals (a very small pressure)

Since the Earth's mean radius is 6,371,000 meters, that would make its total cross-sectional area:

A = π(6,371,000)²
A = π(4.0589641 x 10¹³)
A = 1.2751612 x 10¹⁴ square meters

Multiply that by the pressure to get the total force on the Earth:

F = (1.2751612 x 10¹⁴)(1.3976783 x 10^-19)
F = 0.00001782265 newtons

To find the acceleration this force gives the Earth, we divide this force by the mass of the Earth:

Acceleration = 0.00001782265/(5.97237 x 10²⁴)
Acceleration = 2.984184 x 10^-30 meters per second squared

To get the total increase in velocity that this would have given the Earth over its entire 4.5 billion-year (1.42 x 10¹⁷ second) lifespan, we multiply the acceleration by the age:

Velocity = (1.42 x 10¹⁷)(2.984184 x 10^-30)
Velocity = 4.2378158 x 10^-13 meters per second (extremely slow)

So even after 4.5 billion years of shining on the Earth, Proxima Centaur's light still has a negligible effect on Earth's speed.