# Matter and the speed of light

Status
Not open for further replies.
N

#### nopatience

##### Guest
what happens to matter (that theory's suggest) when it reaches the speed of light?

N

#### nacnud

##### Guest
As the velocity tends to c and for an outside observer<br /><br />mass tends to infinity<br />lenght tends to zero<br />time tends to zero

N

#### newtonian

##### Guest
nacnud - So what happenned in inflation theory with FTL expansion? I've heard the space expanding vs. matter moving explanation.

N

#### nacnud

##### Guest
The difference with inflation is that space expanded at superluminal velocities, the matter didn't accelerate.

O

#### odysseus145

##### Guest
What does "length tends to zero" mean? I understand the other two, but I've never seen this one. <div class="Discussion_UserSignature"> </div>

N

#### nacnud

##### Guest
Relativistic Length Contraction basically means what is says, to an outside observer an object is shorter in the direction of motion when at relativistic velocities than at rest. So if a 20 foot pole was travelling fast enough it would fit in a 10 foot shed and you could close the doors!<br /><br />Follow the link for more information.

S

#### sernpiat

##### Guest
We all know the barrier forbidding things to travel at c. But, is it possible to create something (eg sub-atomic particle) that is already faster than light?<br /><br />Negative length<br />Negative time dilation<br />Negative Mass<br /><br />Perhaps just my wild thinking...

J

#### jcdenton

##### Guest
<font color="yellow">But, is it possible to create something (eg sub-atomic particle) that is already faster than light?</font><br /><br />'Tis possible.<br /> <div class="Discussion_UserSignature"> </div>

N

#### nacnud

##### Guest
What a lovely spurious article, you just gota love CNN for getting things upside-down. The effect is caused my the difference between the group velocity and the phase velocity, physics web explains the difference.<br /><br /><font color="yellow">Special relativity prevents any object with mass travelling at the speed of light, and the principle of causality - the notion that the cause comes before the effect - is used to rule out the possibility of superluminal (faster-than-light) travel by light itself. However, a pulse of light can have more than one speed because it is made up of light of different wavelengths. The individual waves travel at their own phase velocity, while the pulse itself travels with the group velocity. In a vacuum all the phase velocities and the group velocity are the same. In a dispersive medium, however, they are different because the refractive index is a function of wavelength, which means that the different wavelengths travel at different speeds. Wang and colleagues report evidence for a negative group velocity of -310c, where c (=300 million metres per second) is the speed of light in vacuum.</font><br /><br />It's still a cool effect though <img src="/images/icons/smile.gif" /><br />

J

#### jcdenton

##### Guest
It's a long shot from any application but it's impressive nonetheless.<br /> <div class="Discussion_UserSignature"> </div>

N

#### nacnud

##### Guest
not if the shed wasn't moving... although I admit that the shed doors wouldn't be closed for long <img src="/images/icons/smile.gif" />

V

#### vogon13

##### Guest
Thought experiment:<br /><br />I stretch a string form here to LMC (160000 ly, more or less) Every light year there is a knot in the string. I fire up a really fast Prometheous engine cluster with all the upgrades possible and follow the string closely to its destination at a speed not quite that of light. Let's say I go fast enough so that due to the twin paradox I have only aged 50 years. I check my ababacus upon arrival and note that I have counted 160000 knots. From my point of view, I have traveled at 3200c. But I do note that when I get home, all my magazine subscriptions have been expired for roughly 3 ice ages. I then join a support group for time displacement victims. Seriously, these are effects and conditions that are just not intuitive for creatures born, raised and evolved on a world where general and special relativity place such a tiny role in our daily existence. <br />These postings and threads are a collective way for us to ponder the seemingly imponderable. It's how we learn things. Thanx for being. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

N

#### newtonian

##### Guest
vogon13- Hi!<br /><br />3200c? Do you mean 3200 times the speed of light?<br /><br />At near C, just below, you will take 160,000 years plus to reach that destination perhaps near our galaxy halo.<br /><br />I do not see how you could avoid aging 160,000 years one way.<br /><br />Can you explain this paradox?

V

#### vogon13

##### Guest
Einstein tried, I'm not sure I have the articulation skills needed, but briefly; as you accelerate, time slows down for you, but every one else left behind ages at normal rate. You also shrink in the direction of your motion (Fitzgerald contraction). This time dilation effect has been noted on subatomic particles and measured by atomic clocks in flight. In my thought experiment I traveled at 695000000 miles per second. To an outside observer, I traveled at 99.99+% SOL. While in flight, just to kill some time, if I had measured the SOL in my little Prometheous hot rod, regardless of whether I measured a ray of light going from front to back, back to front or a variation on side to side, I would have always measured SOL as 186000 MPS. The weirdest part of this for me is knowing SOL is 186000 MPS and that I myself with my own calendar and abacus would have calculated my trip velocity at 3200c, and that I accept relativity as an accurate desciption of universe. It's just tough wrapping noodle around all of this. <br /><br /><br /><br />Not only is the universe stranger than we imagine, it's stranger than we can imagine.<br />-some one a whole lot smarter than me <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

M

#### mooware

##### Guest
I think it's called Lorenz contraction. But essentionally you are correct, the faster you go the slower time goes for you, as well as shrinkage.<br /><br />If you were in a car, doing 120 mph, your buddy said it took you 30 seconds from point a to point b. the stop watch in your car said it took you 29.99998 seconds.<br /><br />same with the car length. The manufacture states it's 16 feet long, if you could measure while you were traveling the car would be 15.99998 (Not meant to be accurate, just an example)<br /><br />Much slower than light the effect is negligable, but once you hit any decent fraction of light, the effect is more dramatic.<br /><br />Hey, the faster you drive the longer you live.. Well, unless you hit something of course.. <img src="/images/icons/wink.gif" /><br /><br /><br /><br /><br /><br />

Status
Not open for further replies.

Replies
1
Views
590
Replies
5
Views
967
Replies
10
Views
2K
Replies
25
Views
3K
Replies
0
Views
363