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# A question for you physicists out there...

At what speed would going any faster get you to your destination later than staying at the same speed? ie a car going at 30mph gets to the destination at a certain time, if you sped up to 40mph you'd get there earlier (ignoring traffic etc, maybe I should've said space ship!). So what's the magic speed?

Please note: I don't know the answer, but I'm certain there is a magic speed.

i think it was 970mph until 2004 when the law changed and it was then set at 950mph.

Original Poster

davidandhismower

i think it was 970mph until 2004 when the law changed and it was then set … i think it was 970mph until 2004 when the law changed and it was then set at 950mph.

Nope, will be much faster than that.

Banned

Why would getting there take longer the faster you go?

Banned

greatest666

Why would getting there take longer the faster you go?

Magic (_;)

Benjimoron

Nope, will be much faster than that.

it was a joke - if you know the answer then why is there a question?

Original Poster

greatest666

Why would getting there take longer the faster you go?

Because at the speed of light, travelling an inch would take you until the end of time to travel. Therefore isn't there a point at which travelling slower gets you somewhere quicker? Or maybe the magic point is just the speed of light?

Banned

No0b!\$T

Magic (_;)

like jinis?

Banned

Benjimoron

Because at the speed of light, travelling an inch would take you until … Because at the speed of light, travelling an inch would take you until the end of time to travel.

It would?

Original Poster

hmmm, think I'm a bit confused actually. I'm considering it from the point of view of the person doing the travelling, ie the time dilation they would experience. To everyone else you would be travelling at the speed you are travelling and they wouldn't experience the warping of time.

The speed of light, 3x10^8 m/s. Although you wouldn't actually get there later, you would appear to warp there though.

Josh

Original Poster

greatest666

It would?

Well, kinda!

If you could travel at the speed of light (you can't for many reasons), you'd be accelerated through time at an infinite rate, ie you'd end up at the end of time in an instant. You in effect couldn't even travel an inch at the speed of light as by the time you did time would have ended!

r3tract

The speed of light, 3x10^8 m/s. Although you wouldn't actually get there … The speed of light, 3x10^8 m/s. Although you wouldn't actually get there later, you would appear to warp there though.Josh

that sounds like a good answer, i told him that, honest! :-)

Banned

Benjimoron

Well, kinda!If you could travel at the speed of light (you can't for many … Well, kinda!If you could travel at the speed of light (you can't for many reasons), you'd be accelerated through time at an infinite rate, ie you'd end up at the end of time in an instant. You in effect couldn't even travel an inch at the speed of light as by the time you did time would have ended!

I don't that is true.

Original Poster

r3tract

The speed of light, 3x10^8 m/s. Although you wouldn't actually get there … The speed of light, 3x10^8 m/s. Although you wouldn't actually get there later, you would appear to warp there though.Josh

Yes, I've been thinking about it from the point of view of the traveller. Rather than get there later, your trip would feel much quicker. ie going a light year at quarter the speed of light would take 4 years and feel like about 4 years. Going at 9/10 the speed of light it would take about 1.1 years but feel like a few weeks probably.

Original Poster

greatest666

I don't that is true.

Well, Einstein was an idiot then!!!

it depends how good your brakes are.
if you travel too fast for your brakes then its going to take you a long time coming back isnt it?

You need to create a worm hole between your 2 points, which travels through time as well as space.

Original Poster

anewman

You need to create a worm hole between your 2 points, which travels … You need to create a worm hole between your 2 points, which travels through time as well as space.

It's a bit late, maybe I'll do that tomorrow!

As I said on another thread, I love the way that time slows down as you travel faster, basically allowing people to make massively long trips across space within their lifetimes, rather than having to carry the food etc to keep the people alive for many generations. It's almost as if the universe was designed this way to allow us to explore. Without this phenomenon it'd probably be impossible to make the massive light year journeys across space.

I should add, that to the observer you'd appear to arrive later than you actually do. If you left travelling at twice the speed of light for example, and travelled for 1 second, to an observer it would appear like it took you 2 seconds to get there.

If you travel even slightly faster than light you will appear to disappear, until you slow down again.

Also, if you were travelling at precisely the speed of light you would probably appear to be a big blob for as long as you remained at the same speed. A bit like if your computer lags and you can drag a window around the screen which then replicates itself all over the place.
Edited by: "r3tract" 3rd May 2011

Original Poster

r3tract

I should add, that to the observer you'd appear to arrive later than you … I should add, that to the observer you'd appear to arrive later than you actually do. If you left travelling at twice the speed of light for example, and travelled for 1 second, to an observer it would appear like it took you 2 seconds to get there. If you travel even slightly faster than light you will appear to disappear, until you slow down again.Also, if you were travelling at precisely the speed of light you would probably appear to be a big blob for as long as you remained at the same speed. A bit like if your computer lags and you can drag a window around the screen which the. Replicates itself all over the place.

I would say no to that. I'd hazard a guess that to the observer you'd appear to be going slower than you actually were, but not disappear. You'd still be giving off light, it just wouldn't get anywhere as quickly as you would! Either way, impossible to travel that fast!!!

If it was a woman driving then it'd take her longer to get there.

How fast do you need to go to occupy all points in space at the same time?

No, I think you would disappear, because the light reflects from a light source on the person travelling, then onto the eyes of the observer. If you are moving too fast for the light to catch up with you, then it can't reflect and so you will not be seen.

Josh

anewman

How fast do you need to go to occupy all points in space at the same … How fast do you need to go to occupy all points in space at the same time?

You wouldn't be able to occupy all points in space a the same time, but you could look like you were occupying all points in space at the same time

Josh

Original Poster

r3tract

No, I think you would disappear, because the light reflects from a light … No, I think you would disappear, because the light reflects from a light source on the person travelling, then onto the eyes of the observer. If you are moving too fast for the light to catch up with you, then it can't reflect and so you will not be seen.Josh

Yes, but there would be plenty of light rebounding off your ship from ahead of you, or 90 degrees etc, fair enough no light would catch up with you and bounce back tho. You may also have lights on the ship too?

whatsThePoint

A woman would have to drive 10x as fast to allow for time parking once … A woman would have to drive 10x as fast to allow for time parking once she got there

A women would have to drive at the speed of light to catch up one of us male drivers

Benjimoron

Yes, but there would be plenty of light rebounding off your ship from … Yes, but there would be plenty of light rebounding off your ship from ahead of you, or 90 degrees etc, fair enough no light would catch up with you and bounce back tho. You may also have lights on the ship too?

Ah, that's true. I didn't think of the lights on your ship. Yeah they'd probably appear as a solid trail.
Edited by: "r3tract" 3rd May 2011

Original Poster

r3tract

Ah, that's true. I didn't think of the lights on your ship. Yeah they'd … Ah, that's true. I didn't think of the lights on your ship. Yeah they'd probably appear as a solid trail.

But suprisingly, if you travelled at the speed of light, you'd still see your headlights shoot off into the distance. It would seem normal that going at the speed of light your headlights would effectively never make it in front of you.

Benjimoron

Well, kinda!If you could travel at the speed of light (you can't for many … Well, kinda!If you could travel at the speed of light (you can't for many reasons), you'd be accelerated through time at an infinite rate, ie you'd end up at the end of time in an instant. You in effect couldn't even travel an inch at the speed of light as by the time you did time would have ended!

Not entirely true, You can catch up with light and even go faster. An experiment was conducted by a group of physicists (cant remember who but i think it was a collaboration with einstein and a indian physicist in the 1940s) who had cooled the atmosphere to almost 0 Kelvin (its impossible to get to exactly 0 Kelvin) and they had been able to slow light down so that you could actually see it going from one side of the tank to the other..... im a geek so i thought it was amazing.

This is all a load of trash since we aren't going to be able to travel faster than light for the forseeable future.

The only way this would work would be if you were driving so fast you overshot your destination so had to double back I imagine...

anewman

Which is the most accurate of these then? … Which is the most accurate of these then? http://www.youtube.com/watch?v=Kj178APgdnoI liked this one most theatrically http://www.youtube.com/watch?v=sHyy6F_GgsM

imagine if a woman was driving that thing...... she woudl have gone that fast in reverse and knackered all the ships

Original Poster

Rupz

Not entirely true, You can catch up with light and even go faster. An … Not entirely true, You can catch up with light and even go faster. An experiment was conducted by a group of physicists (cant remember who but i think it was a collaboration with einstein and a indian physicist in the 1940s) who had cooled the atmosphere to almost 0 Kelvin (its impossible to get to exactly 0 Kelvin) and they had been able to slow light down so that you could actually see it going from one side of the tank to the other..... im a geek so i thought it was amazing.

Slowing light down isn't the same as mass going the speed of light (in a vacuum I should say).

Light travels slower through water, or very slowly through the sun. It's fastest through a vacuum as there's less in the way to slow it down!

Original Poster

tomwatts

This is all a load of trash since we aren't going to be able to travel … This is all a load of trash since we aren't going to be able to travel faster than light for the forseeable future.The only way this would work would be if you were driving so fast you overshot your destination so had to double back I imagine...

I would say that you can't ever travel the speed of light. It would require infinite energy, would accelerate you infinitely through time, your length would become zero as you would extend into time and not length anymore. You'd therefore be of infinite mass.

I can't see any way around it lol!

Benjimoron

I would say that you can't ever travel the speed of light. It would … I would say that you can't ever travel the speed of light. It would require infinite energy, would accelerate you infinitely through time, your length would become zero as you would extend into time and not length anymore.

plus youd probably be caught by a speed camera anyways

Original Poster

The way I see it, you are in 4 dimensions, x,y,z and time. If you travel at the speed of light, then you no longer have length and you will only exist as a 2d object that extends until the end of time.

Benjimoron

Because at the speed of light, travelling an inch would take you until … Because at the speed of light, travelling an inch would take you until the end of time to travel. Therefore isn't there a point at which travelling slower gets you somewhere quicker? Or maybe the magic point is just the speed of light?

??? how would travelling at 186000 miles in a second take you until the end of time to travel an inch ? that would be travelling at the slowest speed possible
at the speed of light to travel an inch would take.....
well you could travel 186000 miles in one second and there are 63000 inches in a mile so i guess it would be 8.5 -11 of a second so pretty instantaneous ....

Original Poster

KipperRSA

??? how would travelling at 186000 miles in a second take you until the … ??? how would travelling at 186000 miles in a second take you until the end of time to travel an inch ? that would be travelling at the slowest speed possible at the speed of light to travel an inch would take.....well you could travel 186000 miles in one second and there are 63000 inches in a mile so i guess it would be 8.5 -11 of a second so pretty instantaneous ....

Because if you actually hit the speed of light, the rest of the universe would be aging at an infinite rate. The end of the universe would happen the instant before you could actually get to the speed of light.

Remember that to get to the speed of light you'd have to accelerate there too, ie you'd be travelling at near the speed of light for some time and constantly accelerating, the instant before you hit the speed of light you'd have already gone to the end of time!

Banned

Remember that light travels at the speed of light. Light doesn't take an infinite amount of time to travel an inch and neither would anything else travelling at the speed of light.

Anyway, you're all over-thinking it. If you pass a police car at 40mph in a 30 zone you will arrive at your destination later than if you had been travelling at 30mph. I win.

r3tract

No, I think you would disappear, because the light reflects from a light … No, I think you would disappear, because the light reflects from a light source on the person travelling, then onto the eyes of the observer. If you are moving too fast for the light to catch up with you, then it can't reflect and so you will not be seen.

Benjimoron

Yes, but there would be plenty of light rebounding off your ship from … Yes, but there would be plenty of light rebounding off your ship from ahead of you, or 90 degrees etc, fair enough no light would catch up with you and bounce back tho. You may also have lights on the ship too?

r3tract

Ah, that's true. I didn't think of the lights on your ship. Yeah they'd … Ah, that's true. I didn't think of the lights on your ship. Yeah they'd probably appear as a solid trail.

If the observer took one step in the same direction you were travelling (whilst viewing you), the speed you were then travelling at would be less that the speed of light relative to the observer & you would come into view.

I think.

BFN,

fp.