/sci/ - Science & Math » Thread #2983646

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Anonymous Tue 03 May 2011 02:22:00 No.2983646 View View Reply Original Report

Quoted By:

An object with mass can't reach the speed of light, because it would require an infinite amount of energy to reach that velocity. That I do understand. Here's what I don't understand: can't reach the speed of light in relation to what?

Anonymous

Anonymous Tue 03 May 2011 02:25:00 No.2983661 Report

Quoted By: >>2983680

to anything

Anonymous

Anonymous Tue 03 May 2011 02:28:00 No.2983679 Report

Quoted By:

any inertial reference frame.

there's a reason it's called relativity

Anonymous

Anonymous Tue 03 May 2011 02:28:00 No.2983680 Report

Quoted By: >>2983682 >>2983695 >>2983745

>>2983661
So two objects with mass can never move in opposite directions with velocities whose absolute sum is greater or equal to the speed of light, am I right?

Anonymous

Anonymous Tue 03 May 2011 02:29:00 No.2983682 Report

Quoted By: >>2983702 >>2983703

>>2983680

Yes. That can't happen, ever.

Anonymous

Anonymous Tue 03 May 2011 02:32:00 No.2983695 Report

Quoted By: >>2983707 >>2983710 >>2983735

>>2983680
>>2983680
relative to each other their velocities would be 0 no?

Anonymous

Anonymous Tue 03 May 2011 02:33:00 No.2983702 Report

Quoted By:

>>2983682
Except the universe is expanding faster than the speed of light.

Anonymous

Anonymous Tue 03 May 2011 02:33:00 No.2983703 Report

Quoted By: >>2983710

>>2983682
What is preventing it? Say that the objects start accelerating (due to some finite force, which will require finite energy). Neither needen't to reach the speed of light; a half is enough. For what reason can't this happen?

Anonymous

Anonymous Tue 03 May 2011 02:34:00 No.2983707 Report

Quoted By: >>2983729

>>2983695
That's right - no. 'Opposite directions' had been given, sire.

Anonymous

Anonymous Tue 03 May 2011 02:34:00 No.2983710 Report

Quoted By:

>>2983703
>>2983703

because of this.

>>2983695

Anonymous

Anonymous Tue 03 May 2011 02:37:00 No.2983729 Report

Quoted By:

>>2983707
>>2983707
yes opposite directions. The speed at which the 2 objects move away from each other may theoretically exceed the speed of light but its dependant on the point of observation.

However, when considering 2 bodies and their VELOCITY (as opposed to SPEED) direction has effect.

Anonymous

Anonymous Tue 03 May 2011 02:38:00 No.2983735 Report

Quoted By: >>2983749

>>2983695
lol wut can't you think relative velocity would never be 0 if they are moving away from each other

if X is goung at a speed of 3mps and y is going 1 mps the relative speed between either of them is always 4mps

<---x y->

Anonymous

Anonymous Tue 03 May 2011 02:39:00 No.2983745 Report

Quoted By:

>>2983680
You are mistaken. The relative velocity between two objects moving in opposite directions atv_1andv_2is notv_1 + v_2
v_1 + v_2 \over 1 + v_1 v_2 / c^2
http://en.wikipedia.org/wiki/Velocity-addition_formula#Special_theory_of_relativity

Anonymous

Anonymous Tue 03 May 2011 02:40:00 No.2983749 Report

Quoted By:

>>2983735
learn thedifference between speed and velocity.

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