Sensei

It is really a crazy job for a 15-year-old to understand and study string theory. If I could do that, I would have break the world record. Anyway, I will try. Thanks for promoting enthusiasm for me to study string theory.

You should concentrate on classical physics. When it will have no mysteries to you, learn Standard Model.

Then you can go to unconfirmed theories. Without extensive knowledge you can't even judge if something is correct or incorrect. Plausible or not.

Otherwise you're in kinda like position of somebody who is reading about calculus without knowing what is multiplication..

For example, if Nicholas Kang now asks some question about string theory, let us say why 11d for a concrete example, I can explain to him why in general terms, but I would not expect him to go through the calculations again himself (you can find calculations in many string theory textbooks). So, many people have verified why 11d using related but slightly different arguments and so everyone is happy with this. But again, Nicholas Kang may not yet be in a position to understand the steps of the calculations, he cannot verify this for himself.

I remember other thread on SFN where person interested in string theory asked what are all these 11 dimensions. And nobody, literally nobody, could answer...

I don't think so he asked for precise math. Just simple explanation.

we know pure water has density 1g/cm cubed

But first you need to verify that water has 1 g/cm^3

Take f.e. glassware with volume scale, put it on Weighing scale, reset settings, fill with water, read volume and mass. Calculate density of substance in g/cm^3.

Some scientists did it with the all chemical elements, the all chemical substances ever produced.

It was repeated over and over again during the last couple hundred years with better scales to receive more precise results.

or maybe other sophisticated apparatus if possible.

You can take a bit of substance, let's say 100 grams, measure it's volume, and then extrapolate to higher mass, higher volume.

That's how you can calculate mass of Earth. Average density of Earth multiplied by volume = mass. Volume of Earth = 4/3*PI*radius of Earth^3

Sensei, you mean I shouldn`t simply trust one`s statement?

That was quote on top of some Renaissance school if I recall correctly.

Don't trust anybody words. Verify them all by yourself.

You don't have to blindly believe what scientists say, but there should be some element of trust here. Not that I am sure it is relevant to the discussion here.

If some scientists is publishing his/her discovery, other people (not just scientists) can check it and verify and confirm or contradict (perhaps showing where has been made mistakes).

Trust is necessary only if somebody doesn't want to learn.

If I say you 1 m^3 volume of water has mass 1 ton. You Nicholas, can believe me on word, or check it by yourself. Tell me how you would do such experiment.. ?

wget doesn't preserve the search function.

I have no idea what search function you're talking about.

Wget is simply downloading what you will tell to download..

I don't know what to do. I have programs downloading the data, but if we could just get a snapshot of the entire webpage and every possible search for the day/week/month then I could really do something with that.

You can generate your own HTML page with just links f.e.

http://www.server.com/2014/01/01/

http://www.server.com/2014/01/31/

http://www.server.com/2014/12/01/

http://www.server.com/2014/12/31/

Then use wget on your own web page.

And wget will find links, and download stuff they're pointing to.

Or prepare script with many rows with "wget args [some url]"

And execute dynamically created script.

Personally I am using .NET Framework Net::WebClient::DownloadFile() or DownloadString().

We can have list (f.e. 1000+) of proxy HTTP servers, and use them instead of our own IP address, so web server owner won't know that we're downloading large quantity of data. Each request will be from different proxy.

You need application that is recursively analyzing HTTP pages, searching for links and downloading,.

Such as wget.

If you will make f.e. 1 undividable length unit 1 femtometre (10^-15 m) everything what we know (especially macro scale & cosmic scale) will appear really big.

Atom of gold has diameter ~288 pm = 288*10^-12 m.

So 288*10^-12 / 10^-15 = 288000 base units.

Visible violet photon has wavelength 400 nm.

From perspective of 1 femtometre, it's 400,000,000..

Why I can`t have millibites?

http://en.wikipedia.org/wiki/Bit

No, you cannot have mili bits. You can't even have half of bit.

However you can have integer multiply of bits.

You can have Mega bit for instance (typically used in network transmission speed Mbps = Mega bits per second).

If you have 1 GB of memory stick, it's 8 * 1024 * 1024 * 1024 = 8589934592 bits.

It's similar case, from other discipline, as in physics quantity of electrons, protons or neutrons that must be integer number. You can't have half of electron, half of proton, half of neutron.

Quarks is made up of string.

That's assertion. Quarks could be theoretically made of something smaller, but not necessarily strings.

String theory is just one of many theories.

Difference is that it has many (theoretician) scientists on its side.

That does necessarily make it more plausible/probable.

Simply it's well known by public (from just name mostly). Ask people for string theory math..

 

You can measure how long and wide and big and the size of quarks. You measure it. If let say quark is 1 meter, than what will you see if I say I want to see the 1centimeter in the quark? I can somehow separate a quark into tiny pieces? In my opinion, to know the composition of quark, you can only use a particle accelerator and smash two quarks then examine the remnants. How is it possible to separate quarks? They are held strongly by strong nuclear force. It seems impossible to do so.

It always looks impossible, until somebody invent a way to do it.

And then get Nobel prize..

BTW, look at neutral pion particle decay mode.

http://en.wikipedia.org/wiki/Pion

I did rethink my question. It seems that there is no final answer to this question. You see, if string is the smallest thing in the world, then what is the composition of string?

What is composition of bit? (in computer sense)

We know that it can have value 0 or 1 (kinda like property of bit),

and we know its address (kinda like position of bit).

We can read bit, write bit, compare two bits, store it on disk, restore,

group them to byte (8 bits), short (16 bits), long (32 bits) etc.etc.

I am not saying that Universe is some kind of database or so. Universe is "alive". Particles interact constantly.

But as you can see in above example, not everything has to be made of infinitely smaller things.

Bit is unbreakable. It's fundamental.

A. Erwin Schrödinger

B. Marie Skłodowska-Curie

The best is to see it on your own eyes.

If you will place magnet/electromagnet in Cloud Chamber and send beam of particles, or from radioactive decay, you will see how they behave in magnetic field based on their charge, mass, and momentum.

Building your own Cloud Chamber costs $20. Just find steady source of dry ice in your area.

Well here is what I got so far:

 

 

C= 62400000000000000000 C charges per second

No,no,no...

In Coulombs Law you don't have flowing charged particles (so you can't say "charges per second"). They are stationary. Motionless.

At least during verification of law we're not using moving charges.

When Coulomb created his theory, batteries didn't exist yet.

http://en.wikipedia.org/wiki/Charles-Augustin_de_Coulomb

http://en.wikipedia.org/wiki/Alessandro_Volta

Distance between leafs in electroscope device is changing the more it's "charged".

Leafs are further each other the more electrons gathered on them.

Distance between leafs = r in equation.

Q symbol is used to denote charge not C. C is unit.

http://en.wikipedia.org/wiki/Electric_charge

Are you reading the all articles that are posted here?

"charges per second" has sense in electrical circuits, when electrons from one side (negative - electrode) of battery flows to other side (positive + electrode).

9.7879*10e^-13*11.7=0.00258849374

 

 

??

If you have number f.e.

1000

you can write it also using scientific notation

1e+3 or 1e3 (+ is default)

Other example:

1.23e-2 = 0.0123 = 1.23*10^-2

After exponent symbol you don't/shouldn't have power ^ symbol.

Read this

http://en.wikipedia.org/wiki/Scientific_notation

In many physical equations f.e. radioactive decay with mean-life instead of half-life there is used e mathematical constant

http://en.wikipedia.org/wiki/E_%28mathematical_constant%29

Don't confuse these two things!

When I have to quickly enter very small number to calculator often I am dividing by large positive number, f.e. I want to enter 1.602e-19.

I am entering 1.602, hitting divide, and entering 1e19, and calculator is showing 1.602e-19.

You can also enter 1.602, press EXP, then +/-, then 19, and calculator will show 1.602e-19.

But much easier is doing calculations in f.e. OpenOffice SpreadSheet or Excel.

You're mixing everything..

6.24*10e18 = C = 6.24*10e18 = 62400000000000000000 C charges per second ????

Electron has charge -1.602*10^-19 C (Coulombs)

It's elementary charge

http://en.wikipedia.org/wiki/Elementary_charge

If we have 6.24*10^18 electrons, we have:

Q=-1.602*10^-19 C * 6.24*10^18 = -1 C (1 Coulomb charge)

I=Q/t

Current in Amperes is Charge divided by time.

For t=1 second

I=1 C/1s=1 A

If ampere meter is connected to circuit and is showing 1 A, you know that it's 6.24*10^18 electrons flowing through wire per 1 second.

Battery that has 1400 mAh (typical NiMH AA for digital camera) has 1.4 * 3600 = 5040 C. So it's 5040 * 6.24*10^18 = 3.14496*10^22 electrons total.

Knowing how many electrons has battery, and knowing how many electrons is used per second, you can calculate time battery will be working in seconds.

With I=1 A, such battery will be working for 5040 seconds.

With I=0.5 A, such battery will be working for 10080 seconds.

etc. etc.

How charge -+1.602*10^-19 C has been calculated? In oil drop experiment.

http://en.wikipedia.org/wiki/Oil_drop_experiment

I would love to calculate this " with my own methods" and return the results here again, for them to be analyzed, I think I am onto something

Coulomb's Law is for stationary charges that gathered on body like previously mentioned by me electroscope leafs.

It costs 20-30 usd. On ebay there is a few. Anybody can build it in a few minutes using jar and aluminum foil.

Buy it or build it, and you will see how it works in practice and about what we're talking.

I've just been wondering, why do we study algorithms in a computer science course.

Algorithms are just a way to precisely define steps to solve a particular problem. This is not just important in computer science but basically in any field.

 

I mean, algorithms just teach us how to solve problems step-by-step in a well-defined manner. These skills are useful not just for computer science but for every branch.

Then why just computer science course has an algorithms course? Why not others?

Suppose so you have array of strings, and have to find string with exact name.

The basic logical way of solving it is to go through all entries of array and compare. Working but slow.

const char *string; // argument

const char *entries[]; // array

int length;

for( int i = 0; i < length; i++ )

{

if( !strcmp( entries[ i ], string ) return( i ); // string found, return index

}

return( -1 ); // string not found, return invalid index -1

For 1000 entries, it will have to compare 1000 strings (at worse case).

For 1 mln entries, it will have to compare 1 mln strings (at worse case).

There are algorithms that can speed up this process.

For instance, you can sort array in alphabetical order.

Then compare middle entry with what we are searching for.

int tmp = strcmp( entries[ length / 2 ], string );

if( tmp == 0 ) // string found,

else if( tmp > 0 ) // string must be in one part of array

else if( tmp < 0 ) // string must be in other part of array

Now you see, one compare function used, and we have just reduced quantity of entries to compare to half of initial.

If initial length of array is 1000

and we will be using such algorithm recursively

we will have quantity of elements to check:

1000

500

250

125

62

31

15

7

3

1

Just 10 compare functions to find string in 1000 elements array, instead of 1000 in previous brute force algorithm.

Where would you learn about such algorithm if not on lesson about algorithms?

So you are saying my humans and wildlife should be bigger than normal?

No.

That depends on whether it would help to survive.

In hot environment & food shortage environment it's favorable to be small.

In cold environment & food shortage environment it's favorable to have a lot of fat and fur.

etc. etc.

Adaptation depends on environment.

If we have molecule of water H₂O at altitude 0, sea level, we need to give it energy to rise it to 1m, and even more energy to turn it to vapor and reach cloud altitude. If this molecule lose its kinetic energy (f.e. give it to N₂ or O₂), it will turn back to fluid state and will have to fall down to the ground of Earth. Airplane, satellite, rocket or anything flying must to not lose its kinetic energy to not fall down.

In high energy physics, in particle accelerators, kinetic energy of particles accelerated to nearly speed of light are turned in collision to another proton and antiproton pair

I don't know about you, but for me it's enough proof that it's real thing.

Is kinetic energy the real thing?

For somebody touching water with 0 C, and later water with 100 C, or touching metal at 0 C then 100 C, he can really see & fell difference.

N₂ molecule has 4.65*10^-26 kg, so kinetic energy with v=340 m/s is just 2.69*10^-21 J (predicted change in mass of molecule 2.99*10^-38 kg)
O₂ molecule has 5.3137*10^-26 kg, so kinetic energy with v=340 m/s is just 3.07*10^-21 J (predicted change in mass of molecule 3.417*10^-38 kg)

There is physical limit how tall can be grass. That depends on internal structure of vegetable (or animal) and environment they live in. During evolution organism tries to adopt and overcome limit (if it's a way to survive). Growing quickly tall means receiving more light from the Sun *)

There was time in Paleozoic when air had a lot of oxygen (~double current value), and organisms that were absorbing oxygen whole skin area were much much bigger than now. After decrease of oxygen percentage, invertebrate can't grow too big.

*) in mine neighborhood last year there was cut two trees (they had 20+ meters and 50+ years old) There was leaved roots in the ground. A week later from roots grow up couple new trees and reached nearly 2 meters. In just a week.

Maize corn, wheat, barley, rice, rye are all examples of grasses.

"Life is just Nature's Way of turning Light into Heat."

Deep sea microorganisms never saw Sun or light.

They are utilizing heat coming from Volcano, and natural heat of Earth.

Image is named "SlowWormSkin_DominicGreves.jpg"

When we measure the distance with a ruler (nevertheless the ruler is metallic, wood or whatever,) we use the length of it (distance in the extremes of ruler) as a unity. They are both ”objective reality of the same kind”.

If your ruler is metallic, when we will be measuring distance at -100 C, 0 C, +100 C, +1000 C its length will be different, as metal shrinks and extends depending on temperature of environment. This effect is used in typical Mercury thermometer.

Somebody ideate a number.

Other players have to find out what is this number.

Player post his number and original author can answer only "higher", "lower" or "equal" - game is done and we know winner.

To not cheat original author has to make photo of his number with monitor in background open with SFN thread visible so we can verify date.

If allowed number is between 0...1000 number should be found after just 9-10 answers, if you know proper algorithm how to play it