Astronomy & Space Exploration

Well, I've been told!

That's all very interesting, actually. Not the shite they taught me in physics at school.

I wish I were smart enough to understand it!
 
Right, can someone in simple terms, explain how time essentially comes to a stop as you travel at the speed of light?

If something is four billion light years away, and you travelled as light does, why would it not take four billion years?
 
Liam147 said:
Right, can someone in simple terms, explain how time essentially comes to a stop as you travel at the speed of light?

If something is four billion light years away, and you travelled as light does, why would it not take four billion years?
Click to expand...

It's the theory of relativity.

Light always travels at the same speed relative to everything else.

Time x Speed = Distance

Let's say light travels at 100mph.

You stand still and someone turns a torch on and you record the light to past you and it travels at 100mph.

The thing with light though is that if you were moving away from the source at 50mph it should travel at 50mph past you but it doesn't, it moves at 100mph still which suggests that Space must bend to balance the equation.

Therefore if you are travelling at the speed of light you actually make space and time 0 in the equation meaning you travel any distance in no time.


I think that's about right in pay and terms.
 
It would take 4 billion years for you to reach it. Lots of bad shit would happen though.


(not a video explaining anything, just a game trying to make science fun!)

There is a great blog explaining quantum weirdness from the point of view of light "riding on a beam of light".

I cant find it though.
 
This might be it. I haven't read it in years so who knows. But from it:

The photon lives in a “go-splat” world. The clock of a photon completely stops the instant it is emitted and stays stopped throughout its journey. The distance traveled by a photon becomes zero as compared to the distance measured by the stationary observer. It may take a photon a billion years to cross from a distant galaxy to our telescope from our perspective, but for the photon, as soon as it is emitted, it arrives – splat; there is no time elapse in the photon world. In effect, the space and time between the photon’s emission and its destination are severely warped.

Therefore, the photon’s world is flat and stapled together, front-to-back, between its start point and its end point. In effect, the photon is touching its emitter on one end and our eye on the other with zero depth of field. Whatever phase it has at the time of emission, it has when it hits our telescope because it is all frozen in time. Physicists call the time experienced by the photon null time and the path the null time path.

It is this stapled together, zero time world that I believe explains much of the quantum weirdness we experience. Our life and experimental experiences are so strong that we can’t easily get our minds around the relativistic phenomena.
Click to expand...

Liam147 said:
Right, can someone in simple terms, explain how time essentially comes to a stop as you travel at the speed of light?

If something is four billion light years away, and you travelled as light does, why would it not take four billion years?
Click to expand...

By the way the last I will say on this, but Quantum Weirdness is very strange.

Riding on the back of a photon.

That blog is great though, even if its wrong.
 
Liam147 said:
Right, can someone in simple terms, explain how time essentially comes to a stop as you travel at the speed of light?

If something is four billion light years away, and you travelled as light does, why would it not take four billion years?
Click to expand...

Time is really the speeding up and slowing down of particles. Remember chemistry in school? Well, you can speed up some chemical reactions by adding heat to the equation and slow some down by cooling them. Some animals can even go into suspended animation when their bodies encounter extremely cold temperatures, which means that the chemical reactions in their body have slowed right down. From the animal's point of view, time has almost stood still. However, everything around it continues at the same speed (eg: a scientist who has frozen the poor critter in the first place). Same thing happens when you approach the speed of light - the particles in your body slow right down because if they didn't, they would actually be travelling faster than the speed of light, WHICH IS IMPOSSIBLE. Therefore, if you were in a spaceship that travelled at near the speed of light, you would not experience much time passing at all. It would appear instantaneous to you, but 4 billion years would've passed on earth.

HTH.
 
Badunk said:
Time is really the speeding up and slowing down of particles. Remember chemistry in school? Well, you can speed up some chemical reactions by adding heat to the equation and slow some down by cooling them. Some animals can even go into suspended animation when their bodies encounter extremely cold temperatures, which means that the chemical reactions in their body have slowed right down. From the animal's point of view, time has almost stood still. However, everything around it continues at the same speed (eg: a scientist who has frozen the poor critter in the first place). Same thing happens when you approach the speed of light - the particles in your body slow right down because if they didn't, they would actually be travelling faster than the speed of light, WHICH IS IMPOSSIBLE. Therefore, if you were in a spaceship that travelled at near the speed of light, you would not experience much time passing at all. It would appear instantaneous to you, but 4 billion years would've passed on earth.

HTH.
Click to expand...


Even if you traveled at the 99.999% of the speed of light compared to Earth you could still move around your spaceship happily. There is no fixed frame of reference. There is only measure one thing against another. As you approach the speed of light your particles DO NOT slow down compared to anything going the same velocity in the same frame of reference as you. Such as the rest of your body.



Edit: I've removed the No's because last time I argued about this I ended up arguing something untrue. feck physics :D
 
rcoobc said:
No. No. No. No. No. No.

Even if you traveled at the 99.999% of the speed of light compared to Earth you could still move around your spaceship happily. There is no fixed frame of reference. There is only measure one thing against another. As you approach the speed of light your particles DO NOT slow down compared to anything going the same velocity in the same frame of reference as you. Such as the rest of your body.

Click to expand...


It's almost instantaneous. I know I mentioned suspended animation, but that was only to describe how time wouldn't have seemed to pass from the animal's point of view. I didn't mean to imply that the space traveller would be in suspended animation.
 
Yeah I think I got what you meant on second reading, I apolligise for my over use of the No's ;)


Going back to that blog its bloody interesting to explain.

There are two processes going here. One process is the real time that our experimenter sees, about 1 nanosecond per foot of photon travel. The photon is traveling through the experiment with real and measurable delays from the emitter to the first slit and from there to the double slits and from there to the film.

The other process is that the photon’s relativistic path is zero so it is in contact with the film and the emitter at once and all of its paths in between are of zero length and require zero time. All paths that can lead to the same path are conjoined. Time of flight and distances for the photon expand only as it passes through the setup. The photon and the observer see simultaneous events differently.

All the events are simultaneous to the photon, but none are to the experimenter.
Click to expand...

In many experiments causality is very different to the observer and the particle in question, but massless particles are something else.

577530301_60ead143c3.jpg
 
MichaelS said:
I can't really wrap my head around energy. I just don't understand, that if photons are not material, it would mean that light is non-physical, while it it clearly is physical. Luckily there are much brighter people than I who can enlighten me.
Click to expand...

Light is matter, photons are matter. But, the matter doesn't mean that it always have mass, it could be substance like atoms, it could be energy or it could be gravitational/magnetic field.

Photons doesn't have mass, I think that this is pretty easy to understand. Just imagine, how many gazillions of photons hit us every day with 300000km/s speed. We would have been destroyed if they had mass. Also, if you set light in an environment, the mass of the entire environment will remain the same, regardless of how long or how many amount of light you inject there.
 
Going out of topic, for people who think that the special theory of relativity is the ultimate knowledge



It makes you think for some time.
 
So, theoretically, things have already happened in the future? But by looking so far away, that the light is still travelling towards us, it's technically looking back in time, so the first we see of something, is technically delayed, as it's already happened?
If that makes sense?
 
Yeah. For example if a star were to go supernova right this second, we wouldn't know about it until the light reached our eyes. Which could be in thousands or millions of years.

The most powerful telescopes are technically looking back in time to billions of years ago. As the objects are so far away the light is only reaching us after almost 13billion years of travel (or more actually). So if you could instantaneously travel from here to there things would look very different than what they do through a telescope.

In essence everything you see happened in the past as the light takes time, billionths of a second, to each your eyes. Which also means that to a human the present doesn't really exist, nor does the past as its already been and gone, and nor does the future as it hasn't happened yet.

Mindfeck.
 
So technically, if I supposedly use a telescope from Venus looking at the earth? I'll be? Seeing the past of the earth, because of the distance needed for the particles to travel to my eyes?

Mindfeck indeed.. but very interesting
 
Yep, it doesn't matter what you are looking it, it all happened in the past. But the further away it is in the distance the further back in time you are seeing it.

Looking at your phone is billionths and billionths of a second in the past, but looking at the sun is about 8 mins in the past.
 
Which means if im from venus coming to earth, ill be commingto the future earth? But does time have central axis thouugh?

Whos the future whose the past in this instance? Who goes first? Paralel existence?
 
JohnLocke said:
Yep, it doesn't matter what you are looking it, it all happened in the past. But the further away it is in the distance the further back in time you are seeing it.

Looking at your phone is billionths and billionths of a second in the past, but looking at the sun is about 8 mins in the past.
Click to expand...

Next time I play online games I'm going to sit closer to the screen to give myself an advantage.
 
Poxbo said:
Next time I play online games I'm going to sit closer to the screen to give myself an advantage.
Click to expand...

It will gave you a great advantage of some nano seconds. You will be unbeatable.
 
Sky1981 said:
Which means if im from venus coming to earth, ill be commingto the future earth? But does time have central axis thouugh?

Whos the future whose the past in this instance? Who goes first? Paralel existence?
Click to expand...

No you will still be observing earth a few minutes behind what the people on earth are experiencing at that exact moment.

Time doesn't have a central axis as it isn't constant. No one goes first, they both exist at the same time it's just that they observe each other at different times relative to where they are.

Edit: It's not that they always exist at the same time, but in the case of the example of Venus and Earth they do.
 
There was an excellent documentary on 'time' a while back, think on the Science Channel or Discovery Channel. It talked about how people seemingly experience time differently. Time may seem quicker to you while another feels it is slow. The show delved into all kinds of theories and explanations. I tried to find the show online last night but after a few minutes of research I stopped.
 
For anyone interested in physics I do recommend this blog. Purely because it actually attempts to solve the problems even if it gets them wrong

And if anyone who can tell me where that blog is wrong, I would be very interested :D
 
Earth had two moons, scientists claim

The Earth’s moon may once have not been on its own, according to lunar scientists.

By Claire Carter
07 Jul 2013

BMBA29_2372236b.jpg

The scientists noted that their proposition differed from the current leading theory, which holds that the Moon was created from material from a giant body that struck the Earth.

The smaller ‘twin’ moon is believed to have only survived a few million years before it collided with the one we see today, leaving just one.

The theory will be explained by Professor Erik Asphaug, from the University of California at Santa Cruz at a conference about the moon to be held at the Royal Society this September.

He said: "The second moon would have lasted for only a few million years; then it would have collided with the moon to leave the one large body we see today.

“It would have orbited Earth at the same speed and distance and just got slowly sucked in until they hit and then coalesced.”

Prof Asphaug told the Sunday Times he believes the landscape of the moon, which appears to have mountains, are the remains of Earth’s smaller moon when the pair collided. The moon's smaller twin is believed to have been about onethirtieth of the size.

The Earth and its moon are thought to have been formed between 30 million and 130 million years after the birth of the solar system, about 4.6 billion years ago.

A total of nine ‘super-Earths’, planets between one and 10 times the mass of Earth. have previously been found.

Scientists from Harvard put forward a theory last year that suggested the Moon was once part of Earth that spun off after they collided with another body. The study was published in journal Science.

Last month astronomers reported discovered three planets, similar to Earth, orbiting around a single star which may be able to support life.

Researchers estimate there could be as many as 100 billion planets similar to the Earth in our galaxy, the Milky Way.

http://www.telegraph.co.uk/science/space/10165036/Earth-had-two-moons-scientists-claim.html
Click to expand...
 
Asteroid could collide with Earth in 2032, say Ukrainian astronomers

Scientists say there is a chance an asteroid could hit our planet in 2032, creating an explosion 50 times greater than the most powerful nuclear bomb.

By Theo Merz
18 Oct 2013

Astronomers say the 1,345-foot (410m) rock could pass by or hit the Earth on 26 August 2032.

The asteroid was discovered moving through the Camelopardalis – or Giraffe - constellation by scientists at the Crimean Astrophysical Observatory in southern Ukraine last week.

“I was watching the Giraffe constellation, monitoring it as part of our comet search programme,” astronomer Gennady Borisov said.

“The first observations show that it moves quickly and is relatively close.”

Astronomers in Italy, Spain, the UK and Russia have now confirmed the presence of the rock, and it has been added to the Minor Planet Center’s list of potentially hazardous asteroids.

If it hit the Earth, the asteroid would create an explosion equivalent to 2,500 megatons of TNT, or 50 times greater than the most powerful nuclear bomb ever used.

However, in reality the threat is minor, with astronomers putting the chance of direct impact at one in 63,000 - the likelihood being that its orbit will miss our planet by some 1.7 million kilometres.

But this did not stop Russian Deputy Prime Minister Dmitry Rogozin announcing that the asteroid would pose a “great challenge for our national space industry” on Twitter.

Mr Rogozin has previously pushed for the development of anti-asteroid defence systems, like former MP Lembit Opik in the UK.

Nasa played down the possibility of impact, with Don Yeoman, manager of the administration’s Near-Earth Object Profram Office, saying: "The current probability of no impact in 2032 [is] about 99.998 per cent.

"This is a relatively new discovery. With more observations, I fully expect we will be able to significantly reduce, or rule out entirely, any impact probability for the foreseeable future."

http://www.telegraph.co.uk/science/...-Earth-in-2032-say-Ukrainian-astronomers.html
Click to expand...
 
Redcafe.net the gift that keeps giving, I came here for the football, but through exploring I have found so many more different/interesting threads.

Just watched Regan's address after the Challenger disaster I was brought there by the West Wing, it all comes from a poem 'High Flight' by John Gillespie Magee Jnr.


Oh! I have slipped the surly bonds of Earth
And danced the skies on laughter-silvered wings;
Sunward I’ve climbed, and joined the tumbling mirth
of sun-split clouds, — and done a hundred things
You have not dreamed of — wheeled and soared and swung
High in the sunlit silence. Hov’ring there,
I’ve chased the shouting wind along, and flung
My eager craft through footless halls of air....

Up, up the long, delirious, burning blue
I’ve topped the wind-swept heights with easy grace.
Where never lark, or even eagle flew —
And, while with silent, lifting mind I've trod
The high untrespassed sanctity of space,
- Put out my hand, and touched the face of God..
 
adexkola said:
Did you take any classes relating to orbital dynamics or spacecraft?
Click to expand...

Yes. Part of my degree program (Aeronautical Science) dealt with Flight (Aerospace) physiology; which deals with the effects on airplanes (and spacecraft) in high altitudes. These effects are like low oxygen, air pressure and the stresses in puts on the human body. Not because you're in an aircraft with cabin pressure means your body isn't under any form of 'stress'.
 
Il Prete Rosso said:
Yes. Part of my degree program (Aeronautical Science) dealt with Flight (Aerospace) physiology; which deals with the effects on airplanes (and spacecraft) in high altitudes. These effects are like low oxygen, air pressure and the stresses in puts on the human body. Not because you're in an aircraft with cabin pressure means your body isn't under any form of 'stress'.
Click to expand...

Interesting, seems your program was more holistic. Why did/do you hate space? Lack of air is much easier to deal with on paper ;-)
 
adexkola said:
Interesting, seems your program was more holistic. Why did/do you hate space? Lack of air is much easier to deal with on paper ;-)
Click to expand...

I always found the idea of being up there a scary one. Even during classes we had videos of shuttles in orbit and just the view up there looking down at the earth with nothing but darkness around you is already creeping me out.
 
You must log in or register to reply here.