Jay m A

iTrader: (2)

Braking suddenly at infinate mass? I hope you've got braided hoses mate

wez_sti

i believe the general consensus is that you wont get any light out but in a simular example,

if you fire a bullet from a gun whilst travelling at the exit velocity of that bullet, the moment the bullet leaves the gun its actual velocity would be double would it not???


another thing i wondered, having done Physics at A level i understand the light speed barrier cant be broken,

but IF you could, in the headlight situation, do you reckon you'd get a flash of light as you broke it as you do a 'bang' when you pass through the sound barrier???

papascooby

The best comparison i'm inclined to use is

Do you hear the sonic boom inside a plane travelling through the sound barrier? Which you don't so I kinda figured the same for light.

wez_sti

my question was a little different to the orig one. asked if you would get flash of light, not wether the person in the car would see it or not...???

Neil Smalley

It all depends on how fast the speed of light is, in the area of space in which you are travelling. Contrary to pop science light speed is'nt a constant as it can be affected by all sorts of things, such as gravity and temperature.

IbizaFR

Yep, the proof of this is that light getss bent by planets etc. Which means a blackhole decelerates light do it cant escape, which also means light leaving the Sun is decelerating, therefore not a constant. Well I have just blown popular scientific myth silly with those facts.

ERGO no one truly knows what will happen if you emmit light whilst travelling at what is perceived as the speed of light.

Also the thory that when you accelerate to the speed of light your mass gets exponentially higher is also wrong. We can easilly proove this. According to this theory even a particle that weighs next to nothing if travelling at the speed of light would be infinately heavy....e.g. the heaviest thing in the Universe, would therefore have a gravitational field capable of sucking the whole Universe in on it.

Ergo a Tachyon(http://www.physics.gmu.edu/departmen...h/tachyons.htm) particle which is basically a hyper accelerated neutron would destroy the universe. Our current theories although good are not 100% accurate and do not take into account temporal and subatomic mechanics which are part of these equations, therefore I consider them crudely accurate for lab experiments but not for the extremes of FTL travel.

If you travelled at the speed of light it is quite possible your optic nerve would be overwhelmed by the light it emmited. Or you would destroy the Universe. Or you would have an extreme build up of space particles on the front of your "car" that would limit your speed like a car ploughing through deep snow.

mart360

lightspeed is sooooooooooooooooooooooooo boring..

move with the times people..

if you havn,t got warp speed your on the sidelines!!!


make it so!!!


mart

carl

Hi! As the speed of light in vacuo is a constant, regardless of the frame of reference of the observer, yes you would "see" your headlights (providing there was anything for them to light up).

(speed of one thing)+(speed of another thing)=(total speed) is a Newtonian approximation which is not valid at relativistic speeds. It's hard to grasp this, as it's been drummed into us so much it becomes "intuitive" but it just isn't true at speeds near c.

papascooby

so who reckons Hawkins got my mail and still trying to work it out?

and I think the people posting the clever answers neeed to post their job/qualifications

and the braided hoses comment - laugh I nearly sh@t

Mick

iTrader: (1)

Hey - and what about this - the speed of light constant c as in e=mcsquared may not be a constant after all http://www.ldolphin.org/cdkgal.html - that could really cause confusion in the lecture halls....


Mick

papascooby

After reading the biography of e=mc2 (superb book), I always thought c was a bit arbritary.

That's the trouble with science (esp. physics), theory based upon theory based upon theory.

And then the 1st one turns out to 2 b bollox

Bubba po

Ho Hum. Einstein said "There are no privileged frames of reference". What he meant was there is nothing that can tell you positively whether you are absolutely stationary or whether you are steaming along at a million miles per hour. All you can ascertain is your velocity relative to other objects. The absolute velocity of those objects cannot be ascertained either. Which is why, no matter how fast you seem to be going with respect to other objects, light speed will always be measured the same. So light would indeed come out of your headlights.

carl

Currently IP network designer.
BSc in Physics with Astrophysics (Kent, 1994)
MSc in Astrophysics (QMU London, 1997)

Mick

iTrader: (1)

As you say Papascooby...

What about all the theory about Jupiter. Scientists (astrophysicists ) knew it all and sent out a probe to take pics and samples...

'Imagine their surprise' when the probe 'fell in' to what was supposed to be the surface of the planet but turned out instead to be a huge dust cloud! LOL funny (OK we engineers have a strange sense of humour... )

Mick

carl

Gas cloud, actually
And I think you'll find the first Jupiter probe didn't get anywhere near the supposed "surface".

Same thing happened with the first Venus probes (crushed by the ludicrous pressure of the atmosphere). But this is all planetary science, not special relativity [Einstein, 1905] which is the original subject of discussion. Although someone did mention the bending of light by gravity, which is part of general relativity [Einstein, 1919, IIRC].

rob oneill

If you had your lights on in space, and you were sat in your car, how would you know they were REALY on? Ha Ha! Just to wreck everyones brains even more LOL

fast bloke

rob - we covered that on page 2

papascooby

we covered that in the question

anyway 4 pages an 80 posts l8r, we still appear to be no clearer.

rob oneill

sorry, ill have to keep up!

fast bloke

you know the light is on cos there is a little green light on the dash that tells you so. All we need to do now is define the frame of reference concerning the relative speed of the little green light in comparison to the outside observer as a function of e or c and whatever (IIRC it depends how fat the driver is)

fast bloke

just been thinking about the whole e=mc2 thing. It can't be true. I can prove it. There is a really really fat bloke lives down the street from me and he is so heavy he can hardly walk. Now if e=mc2 is true, and he is about 3 times heavier than me, surely he must have squillins of times more energy than me

rob oneill

LOL,lost me now!

IbizaFR

WHos gonna upgrade their Scoob to test this. Space suit, a big ramp and a heel of a lot of BHP. Position ramp at end of Salt flats, get up to speed of light jump the ramp. Once in space switch on your lights. You might see the green light but .... how will you know whether you can see your lights in front of you, you are going to have to stick a mondeo on a stick in front of your car so you can see the light hitting the back of it.

If this experiment is not possible, why are we talking about it?

Jamo

iTrader: (23)

the answer to this should be No.

should you be travelling at the speed of light in a cirular formation, you would be more likely to see the light in your rear view mirror that benefit from the light in front of you.

(i presume) lol

Vilma

What are you on E=MC2 is Energy = Mass times the speed of light squared. Thats not the equation you need here. You need to either refer to Newtons law of gravity or Coulombs law. The equation would read more like - Fg - G M1M2 over R2, where G is 6.672 x 10 -11 Nm2 KG-2 is called the constant of universal gravitation, and M1 and M2 are the masses of the particals. Both forces decrease with the inverse of the squares of the seperation and where Coulombs law involves the product of two changes, Newtons Law involves the product of two masses.
As a consequence of gravity, therefore objects near to the surfacw of the earth possess a property that we refer to as weight. The weight of an object is defined as the magnitude of the force of gravity acting on that object. therefore Fg = m1g.

papascooby

someone needs to post a link to this thread on a physicists forum

carl

The image of Subaru drivers is bad enough already...

Neil Smalley

FB
But if you are going the speed of light, how can you tell if the light is on to tell you the light is on. Maybe the answer is for someone to get out of the car as it's going along to check.

carl

One of our lecturers posed a question that started:
"Supposing you're standing at Canterbury East station, and a train comes along at 95% of the speed of light..."
Not something that I could imagine BR (as it was at the time) achieving. Although they could have argued that the trains were on time in their own frame of reference

Vegas 531

If you're travelling at the speed of light, why would you want your lights on?

You'd never brake in time if you saw anything anway!!