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Science and Astronomy Questions
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| spacer | Date: Sunday, 19.06.2016, 02:10 | Message # 511 |
 Star Engineer
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Israel
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| yeah that names more friendly to ppl who isnt professors in that stuff!
but i want to know. what the colors are! how blue qwark is different than red or green quark.
also what is that spin? i try to understand it. i know bosons have spin of 1 or 0 (bosson higs)
and the quarks have spin of 1\2.
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| Hornblower | Date: Sunday, 19.06.2016, 02:22 | Message # 512 |
 World Builder
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| Quote spacer (  ) NOTHING make the strings.
So what if you took a string and cut it with another string? Is 1 string made up of 2 half strings? And what properties do they have?
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| Watsisname | Date: Sunday, 19.06.2016, 02:52 | Message # 513 |
 Galaxy Architect
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| Quote spacer ( ) but i want to know. what the colors are! how blue qwark is different than red or green quark.
Mmm, try thinking about this:
What makes positive charge different from a negative charge? If I gave you three objects, A, B, and C, and you find that A and B attract, A and C attract, B and C repel, and all three attract small, neutral bits of paper, then can you tell me which are positively charged and which are negatively charged?
You cannot.
What you can do is make a model which says that there are two types of "electric charge", and if two objects have the same charge, then they repel, and if they have opposite charge, then they attract. Then according to this model, B and C have the same charge, and A has the opposite charge, but you don't know which is which. You can do a lot more experiments with other charged objects to further support your model that there are only two types of electric charge and that they interact in this way. And you can dive into the study of atomic structure and discover what the charge carriers themselves are -- the protons and electrons -- but your decision of "which is positive and which is negative" is still completely arbitrary. It doesn't matter as long as you stay consistent with your choice.
Same (or at least similar) idea with color charge. There's nothing about a quark that tells us "I have a red charge". Instead we observe that there are three types of strong interaction, and we can model them as being due to three types of "color charge" (there are also anti-color charge for the anti-quarks). What the color charge does is describe the interaction of quarks by exchanging gluons.
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| spacer | Date: Sunday, 19.06.2016, 10:19 | Message # 514 |
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Star Engineer
Group: Users
Israel
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| Watsisname, and what exactly is the spin?
its a movement?
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| Watsisname | Date: Sunday, 19.06.2016, 11:58 | Message # 515 |
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Galaxy Architect
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| The unsatisfying answer is that it is not, and describing what it really is is hard. This gets into the weird, un-intuitive world of quantum mechanics.
An electron's spin is like a spinning ball, but it isn't. They are not balls and they are not spinning. You can make a spinning ball spin faster or slower. You cannot do that to an electron. You can turn a spinning ball to make it spin on any axis. Again, cannot do that to an electron. Electrons don't even "move" in the usual sense. Most of our every day experience of the behavior of objects fails when we apply it to quantum mechanical systems.
For example, a common description of an atom is that electrons orbit the nucleus like planets orbiting a star. That description is way wrong. If electrons actually moved that way, then they would be strongly radiating (accelerated charges radiate), thereby losing orbital energy, and crash into the nucleus in a tiny fraction of a second. All atoms would collapse and we would not exist!
Electrons instead exist more as a fuzzy cloud of probability. There is a probability function across the space of the atom that describes how likely it is for the electron to be found there. Which is weird and unsatisfying, but that's how it works.
Back to "spin", this originally comes from concepts in electromagnetism. The magnetic properties of electrons are similar to that of a tiny, spinning charge. It's almost as if the electron is a little loop of circulating current. So physicists started referring to this property as spin, even though that's not what they are really doing. Instead it is an inherent quality of angular momentum. Subatomic particles have angular momentum in discrete amounts (the angular momentum is 'quantized'). And they have this quality without actually spinning. Which is weird and unsatisfying, but again that's how it works. 
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| steeljaw354 | Date: Sunday, 19.06.2016, 13:20 | Message # 516 |
 World Builder
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Pirate
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| So nothing makes a string then, so everything is basically nothing?
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| Mosfet | Date: Sunday, 19.06.2016, 14:52 | Message # 517 |
 World Builder
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| I think it could be more correct, if the string is the ultimate constituent of matter, that the string simply "exist".
"Time is illusion. Lunchtime doubly so."
Douglas N. Adams
My mods
Asus x555ub: cpu i5-6200u - ram 4gb - gpu nvidia geforce 940m 2gb vram
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| spacer | Date: Sunday, 19.06.2016, 15:16 | Message # 518 |
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Star Engineer
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Israel
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| Watsisname, ok thank you very much!!
i will continue to learn that throught the summer vacation. 
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
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| steeljaw354 | Date: Sunday, 19.06.2016, 15:54 | Message # 519 |
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World Builder
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| So how can nothing make something?
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| spacer | Date: Sunday, 19.06.2016, 16:17 | Message # 520 |
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Star Engineer
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Israel
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| Quote steeljaw354 ( ) So how can nothing make something?
its really hard question i think noone can explain. its like asking how the big bang happend from nothing.
it is happend. It doesn't make any sense to talk about strings as being "made-of" anything. The point of string theory is to create a unified theory of fundamental particles. If they were "made of " something, then they wouldn't be "fundamental" the thing they were MADE OF would be the fundamental thing. also a string if exist is the lenght of a plank. nothing smaller than that can exist in spacetime.
the strings probably been made in the big bang that we cant really know how and why it happend
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Sunday, 19.06.2016, 16:18 |
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| Mosfet | Date: Sunday, 19.06.2016, 16:27 | Message # 521 |
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World Builder
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| Quote steeljaw354 ( ) So nothing makes a string then, so everything is basically nothing?
No.
Quote steeljaw354 ( ) So how can nothing make something?
This is known as a Conundrum, it's a logic trap created by word meanings.
The meaning of "Nothing makes a string" is that a string is the ultimate boundary of the matter, just as Big Bang is the ultimate boundary on the other direction.
What we can learn with science and technology stops there, for now.
Strings, quarks, colors, wave-particle duality: these are all terms borrowed by the material world we experience to grasp some difficult and anti-logic result from mathematical analysis and scientific experiments. Our everyday language is scarcely able to picture those results, so we use is somehow to approximate reality.
Unfortunately the one and only language that better it represents the entirety of physics is mathematics. Beware, it's an approximation too :)
If you think about it, you're typing on a keyboard right now by commanding electrons and electromagnetic fluxes to transmit your thoughts around the globe thanks to technology based on mathematical rules. Space Engine itself is a simulation made by mathematical algorithms in order to paint photons on a surface in a way that our limited senses can assimilate.
It's a new point of view that matters
"Time is illusion. Lunchtime doubly so."
Douglas N. Adams
My mods
Asus x555ub: cpu i5-6200u - ram 4gb - gpu nvidia geforce 940m 2gb vram
Edited by Mosfet - Sunday, 19.06.2016, 16:45 |
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| quarior14 | Date: Sunday, 19.06.2016, 16:33 | Message # 522 |
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| I want to know how the lifetime and age of a star is determined. I know it is linked to mass but there are what ? What is the equation/demonstration to determine this (lifetime and age) ?
Quarior
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| Mosfet | Date: Sunday, 19.06.2016, 16:50 | Message # 523 |
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World Builder
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| That would be the Hertzprung-Russell diagram, if I remember well.
"Time is illusion. Lunchtime doubly so."
Douglas N. Adams
My mods
Asus x555ub: cpu i5-6200u - ram 4gb - gpu nvidia geforce 940m 2gb vram
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| spacer | Date: Sunday, 19.06.2016, 22:28 | Message # 524 |
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Star Engineer
Group: Users
Israel
Messages: 1258
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| it really intersting that there could be a particle we didnt discovered yet that cause the gravity.
the name of the particle is graviton, and has a spin of 2.
its gonna be so hard to discover such particle because the gravity force is weak compare to the others forces.
we discover the particle of electromagnetism (photons) the weak nuclear force (bozons Z and W)
and strong nuclear force (gluons)
but still no particle of gravity! its gonna be big challenge to find it
"we began as wanderers, and we are wanderers still"
-carl sagan
-space engine photographer
Edited by spacer - Sunday, 19.06.2016, 23:01 |
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| Watsisname | Date: Sunday, 19.06.2016, 22:45 | Message # 525 |
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Galaxy Architect
Group: Global Moderators
United States
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| Quote Mosfet ( ) That would be the Hertzprung-Russell diagram, if I remember well.
That's a part of it. An HR diagram is a plot of star luminosity vs. surface temperature, which shows that stars follow particular evolutionary pathways, rather than just having random properties.
One powerful use of it is in determining the ages of globular clusters. The idea is that since all the stars in a cluster formed at basically the same time, then as the cluster ages, more massive stars will evolve off the main sequence first. So as the cluster ages, the the main sequence turnoff propagates down the diagram from top left to bottom right.
But... how do we know the massive stars evolve off the main sequence first? How do we attach an age as a number to a star based on the HR diagram?
To do that, we need to be able to model how stars evolve. This comes from the study of stellar structure, using knowledge from astrophysics, thermodynamics, nuclear physics, and all kinds of stuff. Stellar model building is a huge part of computational astronomy.
Essentially there are four time-independent equations that must be satisfied in a stellar model:
It is effectively impossible to solve these equations together analytically. Instead we must use numerical methods, building up a model of a star which can then be simulated through time. It is from these models that we calculate stellar lifetimes based on initial mass and composition, and how their structure and exterior appearance change over time. HR diagrams then allow us to test the models against what we observe in nature to be sure that the models really work.
Sorry that this might be a more complicated answer to what seems like a simple question -- how do we determine the ages or lifetimes of stars. But the fact is that it's a lot of work, with no simple analytic formula that can be derived.
We can however come up with a general formula for main-sequence lifetimes that is inexact, but "close":
http://hyperphysics.phy-astr.gsu.edu/hbase/astro/startime.html
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