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A speed beyond light question ^^

 
 
spendius
 
  1  
Reply Thu 6 Apr, 2006 05:39 pm
That's simple cray.You want the technical experts on Health and Safety threads.

I think it's something to do with the latent heat of evaporation.You should have a new thermostat fitted and some zappier speakers in the dashboard.

It's Dover school science.
0 Replies
 
hingehead
 
  1  
Reply Thu 6 Apr, 2006 05:44 pm
Howdy crayon

The effect of air blowing over you and cooling you off is generally an evaporative effect. Maybe E would be better at explaining because it involves a number of concepts. But basically.

Heat is energy and measured as temperature.
Temperature is the average amount of heat in the thing you are measuring.

At the molecular level different atoms/molecules have different energy levels - the most energetic particles in your sweat have the ability to transfer from liquid to gas and leave the thin sheen of liquid on your skin.

Each time an highly energetic particle leaves the average energy of the remainder (ie the temperature) drops.

Wind/moving air speeds up this process, because the particles need less of their own energy to disentangle themselves from the sheen and there is an evaporative pressure.

That's why clothes dry faster on windy days.

I have massively simplified this idea - and haven't really touched on water becoming gaseous (ie steam) at temps below 100C either.
0 Replies
 
Steve 41oo
 
  1  
Reply Fri 7 Apr, 2006 06:07 am
hingehead wrote:
... I can answer it myself: you do weigh more during the day....
My question was whether you weigh more at night. Still if you are in Australia...Smile
Steve 41oo
 
  1  
Reply Fri 7 Apr, 2006 06:22 am
hingehead wrote:
I think the train is a dud analogy for this problem.

I agree that the affect of the acceleration of the earth is unchanged and can be ignored - I was referring to the fact that at night you are further from the sun and therefore the attraction between your mass and the sun's is reduced (by the square of the diameter of the earth).
I was going to raise this, you beat me to it. But i think the opposite effect from the gravitational pull of the sun is more pronounced. That can distort the whole planet (think of the affect of Jupiter/Saturn's forces on moons Io or Gannymede). Our own moon causes the tides and when the sun and moon are in alignment, their combined gravity produces exceptionally high and low tides.
0 Replies
 
crayon851
 
  1  
Reply Sat 8 Apr, 2006 03:03 pm
Cool so the cooling effect that you experience from fans was similar to what I thought, except I think you worded it better than what was going through my mind ^^. thx a bunch.

Anyway back to the topic at hand,

So what happens when you go beyond the speed of light? Is there some theory that describes this?

Oh and

You know how our solar system is like an atom i think, with all those protons and electrons orbiting the nucleus or whatever its called ack. But do you think our entire universe is just one small particle in a whole giant thing?
0 Replies
 
ebrown p
 
  1  
Reply Sat 8 Apr, 2006 03:27 pm
The scientific answer to your question, crayon, is that if our understanding of Relativity is correct, you simply can't go faster than the speed of light.

There are good reasons for us to be confident that our Understanding of Relativity is valid.

You can understand these reasons if you take the time to learn the science. But you need to understand that this theory developed over hundreds of years, each new level of understanding is based on the ones before it.

But none of the ideas are that difficult to grasp if you are reasonably smart and make a little effort.

I suggest learning in the order they were discovered.

1) Learn Galilean relativity. This is what I was trying to get accross with the train example which was largely ignored.
2) Understand Newtons addition which involves describing speed and acceleration.
3) Understand the problems Newton;s laws had explaining light and the ways that people before Einstein tried to resolve them.
4) Understand Einsteins extension to the train example which involves light and mirrors and brilliantly resolved the issues unanswered by step three.

Most people don't even understand that speed is only valid when measured relative to something, and the two people can measure the speed of an object and get differing, but equally correct answers.

If you don't start here, you aren't going to understand the arguments behind the theory of relativity.

... in this case you will never understand why the speed of light is considered by most scientists to be an absolute limit.
0 Replies
 
crayon851
 
  1  
Reply Sun 9 Apr, 2006 01:38 am
Well im not too familiar with these theories and such, I just thought it would be cool to explore the possibilities of exceeding the speed of light. For example, when the flash reaches a speed beyond that of light, he fades out of existence.

Which can be seen here

http://youtube.com/watch?v=0MKj5ZSuUYQ
0 Replies
 
sciencewiz123
 
  1  
Reply Fri 14 Apr, 2006 07:12 pm
The whole universe could be destroyed because you are usin an infinite amount of energy but im not sure. Sad
0 Replies
 
USAFHokie80
 
  1  
Reply Sat 15 Apr, 2006 07:20 pm
Instead of thinking about it as "speed" think of it as energy. E=mc^2. The reason the speed of light (c) is the LIMIT... is because as the velocity increases (that is, your energy increases) your mass also increases. As your mass increases, it takes more and more energy to push your speed a little higher. So basically, the amount of energy required to keep pushing your every-growing mass faster and faster, increases exponentially towards infinity. And since we do not have an infinite amount of energy, you cannot reach light speed.

If you are any good with geometry/trig... Einstein said this: All things in the universe are constantly moving at the speed of light. One's speed is the magnitue of his trajectory. We usually describe things in terms of 3 dimensions, x,y and z. For instance, someone can be moving with a vector of <4,7,2> and his speed would be sqrt(4^2 + 7^2 + 2^2) = sqrt(69) = 8.306... That is his speed along that trajectory. Now, Einstein said that there is a 4th dimension...time. So now we have <x,y,z,t> to describe our trajectory. He said that we are always moving at the speed of light, meaning that the magnitude of our <x,y,z,t> vector is equal to c (the speed of light). However, the majority of that "speed" is used in the time dimension. (t is really really really big compared to x,y,z) This also explains how/why time appears to slow down as our speed along the x, y or z axis increases.

For those of you asking about this... read up on Special Relativity... and then General Relativity. There is a *very* good book on this stuff called "The Elegant Universe."
0 Replies
 
ebrown p
 
  1  
Reply Sat 15 Apr, 2006 10:05 pm
USAHokie,

You don't have the slightest idea of what you are talking about. Almost nothing you said is correct.

The amount of energy does not increase exponentially and Einstein never said that all things are moving at the speed of light. One's speed is not the magnitude of his trajectory...

<<Sigh.... it's not even worth the effort...>>
0 Replies
 
spendius
 
  1  
Reply Sun 16 Apr, 2006 05:05 pm
Well go to sleep then.Nobody minds.

In fact,not to put too fine a point on it old chap,nobody gives a flying fucheroonie.
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 12:24 pm
ebrown_p wrote:
USAHokie,

You don't have the slightest idea of what you are talking about. Almost nothing you said is correct.

The amount of energy does not increase exponentially and Einstein never said that all things are moving at the speed of light. One's speed is not the magnitude of his trajectory...

<<Sigh.... it's not even worth the effort...>>


Actually, it is you who is wrong. The magnitude of a vector <x,y,z> is in fact equal to its speed. Look it up in wikipedia... the last sentence in the first paragraph states "Speed is thus the magnitude component of velocity." Here is a small excerpt from http://www.math.com/tables/oddsends/vectordefs.htm in case you don't understand.
"Definition: The magnitude of a vector A of dimension n, denoted |A|, is defined as

|A| = sqrt(A1^2 + A2^2 + ... + An^2)

Geometrically speaking, magnitude is synonymous with "length," "distance", or "speed." In the two-dimensional case, the point represented by the vector A = (A1, A2) has a distance from the origin (0, 0) of sqrt(A1^2 + A2^2) according to the pythagorean theorem. In the three-dimension case, the point represented by the vector A = (A1, A2, A3) has a distance from the origin of sqrt(A1^2 + A2^2 + A3^2) according to the three-dimensional form of the Pythagorean theorem (A box with sides a, b, and c has a diagonal of length sqrt(a2+b2+c2) ). With vectors of dimension n greater than three, our geometric intuition fails, but the algebraic definition remains."

Einstein did in FACT, as a result of Special and General Relativities, conclude that ALL THINGS are moving at the speed of light, but that they are moving THROUGH TIME at the speed of light. He said this when he was explaining the intermingling of space-time.

This perfectly explains the differences in synched atomic clocks when they are moving at different velocities. One on the ground will show a fraction of a second faster than one in an airplane. This is because the one on the plane has increased the components of its motion vector in the x,y,z axis and since our magnitude is fixed, it must decrease the speed through the t axis (time) to maintain the conservation of energy.

Perhaps before you say someone has no idea what he's talking about... You should read up on it. I suggest you start with any high school or college mathematics text book.
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 12:37 pm
Oh... and here it is again if you still doubt me

http://www.mathwords.com/s/speed.htm

"Speed

Distance covered per unit of time. Speed is a nonnegative scalar. For motion in one dimension, such as on a number line, speed is the absolute value of velocity. For motion in two or three dimensions, speed is the magnitude of the velocity vector."


:-D
0 Replies
 
ebrown p
 
  1  
Reply Mon 17 Apr, 2006 01:01 pm
Perhaps spendius is right.

USA (I don't know why I am wasting my time here, but Physics is important to me). Maybe no one else cares in which case this is a complete waste of time.

This statement "speed is the magnitude of the velocity vector" is absolutely correct. Velocity is one type of Vector. If you take the magnitude of this vector, you will get the quantity known as speed.

But not all vectors are velocity vectors. To say, as you do, that "the magnitiude of a vector is its speed" is simply ridiculous. Another common type of vector is the position vector. The position vector doesn't have a speed-- and the magnitude of the position vector is distance.

Do you want to find a link you don't understand to explain your misunderstanding of Relativity?
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 01:07 pm
ebrown_p wrote:
Perhaps spendius is right.

USA (I don't know why I am wasting my time here, but Physics is important to me). Maybe no one else cares in which case this is a complete waste of time.

This statement "speed is the magnitude of the velocity vector" is absolutely correct. Velocity is one type of Vector. If you take the magnitude of this vector, you will get the quantity known as speed.

But not all vectors are velocity vectors. To say, as you do, that "the magnitiude of a vector is its speed" is simply ridiculous. Another common type of vector is the position vector. The position vector doesn't have a speed-- and the magnitude of the position vector is distance.

Do you want to find a link you don't understand to explain your misunderstanding of Relativity?


You obviously didn't read my post. It says "moving with a vector of <x,y,z>" which implies a MOTION vector. I figured it was rather intuitive. Perhaps next time I'll explain more simply. And actually, my understanding of relativity is perfectly fine.
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 01:13 pm
Ya know... That was just rude... so let's look at it, while I'm thinking about it. If you think that my assertion of the direct relationship of mass and energy are incorrect, then it's again you who doesn't understand relativity. Everyone knows the famous equation of E=mc^2. And anyone with common sense knows that it requires more energy to accelerate an object to 20kph than it does to 10kph. So, using that equation, you can obviously see that increasing the energy is directly related to the mass, since the speed of light is fixed.

Are you going to tell me that's incorrect?
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 01:14 pm
Actually, I will retract ONE thing. The increase in mass and energy are not exponential.
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 01:19 pm
ebrown_p wrote:
USAHokie,

You don't have the slightest idea of what you are talking about. Almost nothing you said is correct.

The amount of energy does not increase exponentially and Einstein never said that all things are moving at the speed of light. One's speed is not the magnitude of his trajectory...

<<Sigh.... it's not even worth the effort...>>


And by the way, you said here that the speed is not the magnitude of a trajectory. However, a trajectory is defined as " 1 : the curve that a body (as a planet or comet in its orbit or a rocket) describes in space
2 : a path, progression, or line of development resembling a physical trajectory "

Which can easily be seen an as analog to the motion vector of an object. The trajectory of that object would be the set of points along the vector. And so, yes, speed IS the magnitude of a trajectory.

So no only are you rude, but you are the one who is wrong.
0 Replies
 
ebrown p
 
  1  
Reply Mon 17 Apr, 2006 01:35 pm
A trajectory is a path through space. It has nothing to do with speed.

Since the trajectory is a path (i.e. not a straight line) it can not be represented by a vector. The closest thing to a trajectory that can be represented by a vector is a position, or perhaps a translation.

Again the magnitude of a position or translation vector is "distance" not "speed".

I may be rude, but you will forgive me. I am a bit touchy about people spouting bad physics... especially in this time of creationism and global warming debates. Understanding that science is a precise discipline with right answers is important to me, and I feel is important to society at large.

But when I state that trajectory is a path that can be resolved to a distance, but not to a speed, I am not wrong.
0 Replies
 
USAFHokie80
 
  1  
Reply Mon 17 Apr, 2006 01:58 pm
Did you just say a path cannot be a straight line? The definition of a line is "The geometric figure formed by two points. A line is the straight path[\B] connecting two points and extending beyond the points in both directions."

You are wrong on soooo many levels. A trajectory is a path, that can be straight or whatever, and therefor CAN be described by a vector. For a given vector, the trajectory is the set of points along the vector.

Even a vectory describing motion can be used to calculate points, which in turn describe a trajectory. One can calculate a motion vetor from a set of points (a trajectory).

You can argue with me all you want. You cannot argue with the mathematic definitions of path, line, vecotor, speed and trajectory.

I'm not spouting out poor physics. You simply don't understand the necessary definitions.
0 Replies
 
 

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