period planets.

[Penners]

if i were to go backwards faster than light

I really don't recommend that. You risk meeting yourself coming the other way and disappearing up your own black hole.

Then who'd do the lime plastering?

 

[robgil]

here is a theory , two particles accelerated towards each other in a particle accelerator.
for the observer both particles will be travelling at just under the speed of light. put the observer along side one of the particles and now the oncoming particle will be travelling at just under twice the speed of light.
it wont be time travelling although the perspective of time would be effected slightly as neither particle is standing still. the faster you move away from something the light being reflected from it will slow down so the faster you move towards something the faster you encounter the light reflected from it so it would appear that time has sped up, and you dont have to be travelling at the speed of light to see this time travelling phenomenon..

 

[Flyfisher]

 

[Penners]

:lol: :lol: :lol:

 

[MdB]

here is a theory , two particles accelerated towards each other in a particle accelerator.
for the observer both particles will be travelling at just under the speed of light. put the observer along side one of the particles and now the oncoming particle will be travelling at just under twice the speed of light.

Nope sorry.

Relativity is a fun subject and you have to remember that time itself gets distorted. Nothing can go faster than the speed of light, however you measure it. If you stood on one particle looking at the other, it would appear to be moving towards you at just under the speed of light rather than just under twice the speed of light as time for you will have slowed down. Time goes slower the faster you travel which has been proved by flying clocks on planes. If you do a lot of travelling (at speed) then you will be younger than those who don't. If I remember correctly, a trip to the moon and back makes a difference of something like 10 seconds.

 

[robgil]

interesting stuff , i did read somewhere that because gravity distorts time people who live at high altitude live longer , or look younger , cant remember which now.

 

[Penners]

time itself gets distorted.

I have empirical evidence of this. When Mrs P says "I'll be ready in five minutes", I invariably find myself waiting for at least twenty minutes.

 

[FamilyWiggs]

And full marks to FW for waking the kids - such things are important.

Grrr - we're suffering from an abundance of liquid sunshine in Wales this evening... so we washed, stalked and froze 9kg of damsons and made 4 litres of damson gin and vodka together instead. We'll look for the Jovian experience tomorrow night if it is clear.

Nothing can go faster than the speed of light, however you measure it.

Is the speed of light a constant? If so, when I turn my headlights on in the driveway, then the light is travelling away from the bulb at, well, the speed of light. When I am doing 70mph on the motorway is the light travelling away from the bulb at the speed of light plus 70mph? If not, why not? And if not, how does the bulb know how fast I am going and adjust it's output speed ? :?: :?: :?:

:idea:

 

[Flyfisher]

So, astronomy is off but alcohol induction is a suitable alternative for 4 & 10 year olds. :lol:

Our damsons are being eaten too quickly to make such concoctions.

As for the headlight question, it's all a matter of relativity. You are in the car and would measure the light from the headlamps moving away from you at the speed of light, whatever the speed of the car. A stationary observer, e.g. a pedestrian you are driving towards, would also measure the light beam travelling towards them at the speed of light. Basically, relativity theory says that all observers measure light travelling at the same speed.

Don't ask me to explain why . . . that last sentence is about as far as I got with relativity theory!

 

[Penners]

Is the speed of light a constant? If so, when I turn my headlights on in the driveway, then the light is travelling away from the bulb at, well, the speed of light. When I am doing 70mph on the motorway is the light travelling away from the bulb at the speed of light plus 70mph? If not, why not? And if not, how does the bulb know how fast I am going and adjust it's output speed ?

Oh, come on, FW! You can't blind us with science. Do you really expect us to believe that you drive on a motorway at only 70 mph?

 

[MdB]

Is the speed of light a constant? If so, when I turn my headlights on in the driveway, then the light is travelling away from the bulb at, well, the speed of light. When I am doing 70mph on the motorway is the light travelling away from the bulb at the speed of light plus 70mph? If not, why not? And if not, how does the bulb know how fast I am going and adjust it's output speed ? :?: :?: :?:

My understanding is that if you are standing by the side of the road, the speed of photons leaving your torch and the speed of light of the photons leaving the car passing you is exactly the same. The same is true if you were sitting in the car. For both observers the photons of all light is travelling at the speed of light. The 70mph difference in relative speed between the person at the side of the road and the person in the car is taken up by the fact that for the person in the car, time is moving slower than the person by the side of the road. (*)

The speed of light in materials other than vacuum is less which may make the above not strictly true - I'm not sure. What I do know is that people cleverer than I have managed to slow light down until it actually stops for a few milliseconds or so. I've no idea how this works..

(*) Yes this is very strange. Relativity is very strange as is Quantum Electro Dynamics which also dictates how light travels. Just as unbelievable is my ability to type the above whilst rather drunk so if I were you, I wouldn't believe a word of it....

 

[FamilyWiggs]

Curiouser and curiouser. Light is very strange. I think I read somewhere that it has properties of both a wave and a particle. I wonder what happens to time when you slow down light?

What is time anyway - outside of our subjective perception of the passing of it - which slows and speeds up according to what we're doing. If I read a really boring book for the rest of my life will I live longer, or will it just seem that way? Is there a difference?

I think Steven Hawking's latest book is out round about now. I tried A Brief History of Time when I was a teenager - not sure I got past a couple of pages. I may get the new one - since he apparently sets out "creation" without the need for a God or other sky-faeries. I think from previous reading it goes like this "If you have an infinite period of time to wait around, since it is not possible to prove that matter/big bang can't spontaneously appear, then sooner or later it will". It has a superficial circular sense, but I hope he can expand it a little!

Maybe I should take MdB's advice and get drunk instead?

 

[FamilyWiggs]

Yes - it is out and down to a tenner on Amazon (other bookstores exist, etc):

http://www.amazon.co.uk/Grand-Design-Stephen-Hawking/dp/0593058291/ref=sr_1_1?s=books&ie=UTF8&qid=1285219574&sr=1-1

"Product Description
When and how did the universe begin? Why are we here? What is the nature of reality? Is the apparent 'grand design' of our universe evidence for a benevolent creator who set things in motion? Or does science offer another explanation? In "The Grand Design", the most recent scientific thinking about the mysteries of the universe is presented, in language marked by both brilliance and simplicity. "The Grand Design" explains the latest thoughts about model-dependent realism (the idea that there is no one version of reality), and about the multiverse concept of reality in which there are many universes. There are new ideas about the top-down theory of cosmology (the idea that there is no one history of the universe, but that every possible history exists). It concludes with a riveting assessment of m-theory, and discusses whether it is the unified theory Einstein spent a lifetime searching for. This is the first major work in nearly a decade by one of the world's greatest thinkers. A succinct, startling and lavishly illustrated guide to discoveries that are altering our understanding and threatening some of our most cherished belief systems, "The Grand Design" is a book that will inform - and provoke - like no other. "

 

[MdB]

http://news.bbc.co.uk/1/hi/sci/tech/1124540.stm

 

[robgil]

http://news.bbc.co.uk/1/hi/sci/tech/1124540.stm

i dont get it , they fire a laser at some gas while it is transparent then make it opaque so the laser cant penetrate then say ''look , ive stopped light dead in its tracks'' , i can do that by shining a torch at the end of my garden then holding a large book in front of it!

 

[MdB]

i dont get it , they fire a laser at some gas while it is transparent then make it opaque so the laser cant penetrate then say ''look , ive stopped light dead in its tracks'' , i can do that by shining a torch at the end of my garden then holding a large book in front of it!

1) Stand in front of lit torch - see light from torch
2) Place book in front of torch - no light.
3) Switch torch off - still no light
4) Remove book - see light that was stored in the book (be it for a brief period)

I would guess that it is step 4 that you would have difficulties with. This is what they claim to have done to my very limited understanding.

 

[LadyArowana]

i dont get it , they fire a laser at some gas while it is transparent then make it opaque so the laser cant penetrate then say ''look , ive stopped light dead in its tracks'' , i can do that by shining a torch at the end of my garden then holding a large book in front of it!

1) Stand in front of lit torch - see light from torch
2) Place book in front of torch - no light.
3) Switch torch off - still no light
4) Remove book - see light that was stored in the book (be it for a brief period)

I would guess that it is step 4 that you would have difficulties with. This is what they claim to have done to my very limited understanding.

I didn't have any difficulty with step 4) at all once I stopped using the electric torch and tried something a little more Olympian, the burning book provided quite a good light, but you were right that it didn't last all that long. Maybe I should use a bigger book next time? Is that what they built underneath the Franco/ Swiss border, a really really big book? I'm guessing all the talk of recreating the big bang conditions is when a team of mules is used to rapidly slam this very large book?

 

[Penners]

Maybe I should take MdB's advice and get drunk instead?

Ah - sorry, I thought you were already.

 

[MdB]

Oh dear - seem to have managed to get drunk again...



For those worrying about ageing - All you need to do is sleep downstairs....

http://www.newscientist.com/article/dn19494-standing-on-a-stepladder-makes-you-age-faster.html

 

[FamilyWiggs]

For those worrying about ageing - All you need to do is sleep downstairs....

http://www.newscientist.com/article/dn19494-standing-on-a-stepladder-makes-you-age-faster.html

Hmm - it has long been a personal motto of mine to "Lie low to live longer" - seems those clever boffins at New Scientist have finally caught on. :wink:

Maybe I should take MdB's advice and get drunk instead?

Ah - sorry, I thought you were already.

Pennersh, thatsh a dreadful slur on my character. (D'ya see what I did there? :lol: )