Speed of light

[Over9000]

Firstly, would it be possible to travel at the speed of light?

Now, assuming we can instantly 'teleport' to a planet 65 million light years away and use a telescope that could view anything on the earth, would it be possible to see the dinosaurs living on earth? Assuming they existed.

Theory: I think that because the light from the dinosaur's reflected off the sun is travelling in space at the speed of light so that means after 65 million years, it is 65 million light years away. Therefore if we travel to a planet 65 million light years away instantly, we would be able the light that has just reached this point in space after 65 million years. So theoretically we could view the dinosaurs even though they are extinct.

Secondly (Hardest one which I can not get my head aruond)

So imagine you are able to travel to the edge of the universe. 1. What would we see 2. What would happen if we go beyond the expansion(if at all possible)?

Please do not go off topic, I am very interested in scientific discussions in this thread because I want to join NASA

[TrueTears]

I am honestly not sure about this, but I do not think we can ever travel at the speed of light.

Looking at the equation where c is the speed of light, v is the speed at which someone travelling, t' is the time dilation. So if v = c, then that means an observer seeing someone travel at the speed of light will take FOREVER to see them go by which does not make any sense.

For the dinosaur, I think it is quite possible given the assumptions that you have the telescope and teleporting abilities, then yes I think it would be possible to view the dinosaurs. A famous quote from Hubble, "Equipped with his five senses, man explores the universe around him and calls the adventure Science" shows that anything is possible.

[Over9000]

Interesting TT, however just because we may see the person travelling at the speed of light forever doesn't mean it is entirely impossible.
Also, isn't it interesting how large the universe is, if we arent able to even travel at the speed of light, the universe will never be explored which kind of sucks.

[spesh-gun]

You will learn later in the year (if u study synchotron) that as you appraoch the speed of light, your mass increases, and other properties of the objects dramatically change. This is called the relativistic effect. So it's impossible to travel at the speed of light, the speed is like an aysmptote which u can approach but never touch.

[spesh-gun]

yeh wat true tears said about time dilation is true

Time dilation would, in principle, allow astronauts to travel vast distances well within their own lifetimes. However, relativistic mass increase would make it more and more difficult to continue to accelerate a spacecraft. The factor that determines the amount of mass increase and other relativistic effects is called  (gamma). For an object moving with speed v relative to an observer considered to be at rest (for example, on Earth),  is given by:


 = 1/√(1 - v2/c2)


where c is the speed of light.

The relativistic mass, m, of a body moving at velocity, v, is then


m = m0 = m0/√(1 - v2/c2)


where m0 is the rest mass. Note that when v = 0, this reduces to the non-relativistic result, m = m0. The impossibility of accelerating an object up to the speed of light is shown by the fact that when v = c, m becomes infinite.

Similarly, the relativistic time dilation is given by:


t = t0 = t0/ = t0√(1 - v2/c2)

[Over9000]

You will learn later in the year (if u study synchotron) that as you appraoch the speed of light, your mass increases, and other properties of the objects dramatically change. This is called the relativistic effect. So it's impossible to travel at the speed of light, the speed is like an aysmptote which u can approach but never touch.

good point, however, I wouldn't say it can never touch, in theory it actually can. Light in the form of photons travels at the speed of light, so the speed of light can be reached, maybe what can be said is that objects like metal spacecrafts or carbon life humans can't travel at the speed as their body wouldn't take it

Note: Perhaps we can travel at the speed of light, but we will need to alter our genetic composition, which im sure, in the future wont be too hard

[mark_alec]

Light in the form of photons travels at the speed of light, so the speed of light can be reached, maybe what can be said is that objects like metal spacecrafts or carbon life humans can't travel at the speed as their body wouldn't take it

The only things that can travel at the speed of light have no inertial mass (i.e. photons). In order to make a mass travel at the speed of light, it would require an infinite force (as F = dP/dt, but P approaches infinity asymptotically as v approaches c).

What you said about looking at dinosaurs roaming the Earth from a location 65 million light years away is correct. This is the manner in which scientists know so much about the evolution of the universe, from looking into the distant past by detecting radiation from the furthest reaches of the universe.

[Over9000]

So it would be possible for us to travel at the speed of light if we were able to somehow convert ourselves into pure energy or something?
Would be pretty cool, but then I wonder if we can travel even further beyond the speed of light as it's a pretty useless speed for traveling the universe

Btw: anyone wanna try and have a go at answering this
So imagine you are able to travel to the edge of the universe. 1. What would we see 2. What would happen if we go beyond the expansion(if at all possible)?

[kurrymuncher]

What you said about looking at dinosaurs roaming the Earth from a location 65 million light years away is correct. This is the manner in which scientists know so much about the evolution of the universe, from looking into the distant past by detecting radiation from the furthest reaches of the universe.

I find that concept so incredibly awesome.   

[Over9000]

What you said about looking at dinosaurs roaming the Earth from a location 65 million light years away is correct. This is the manner in which scientists know so much about the evolution of the universe, from looking into the distant past by detecting radiation from the furthest reaches of the universe.

I find that concept so incredibly awesome.  

Yeh, just to think, we could look back at earth before we were even born. Makes me  :smitten:

[mark_alec]

So it would be possible for us to travel at the speed of light if we were able to somehow convert ourselves into pure energy or something?

Sure, if you combine yourself with anti-matter in just the right way, you could be annihilated, with high energy photons emitted (there may be other elementary particles, I am not well conversed with elementary particle physics), but that is kind of useless for travel, since you would not be living

Btw: anyone wanna try and have a go at answering this
So imagine you are able to travel to the edge of the universe. 1. What would we see 2. What would happen if we go beyond the expansion(if at all possible)?

You can't begin to answer this question until you discuss the shape of the universe. If it is infinite, then there is no edge. But if it is finite, there could also be no edge.

Think about the universe being constrained to the surface of a balloon (which is growing or shrinking as you desire), there is no way to get 'off' the balloon, you are always in the universe.

To get a satisfactory answer to your questions, you'll have to undertake graduate in cosmology/astrophysics.

[Over9000]

Yeh, thats what I was thinking mark alec, what is the shape of the universe like?
I think, just my guess, that the universe's shape is incomprehensible. Consider this, you have the center of the universe right, and then as you approach the edge of the universe, what you are actually doing, is in effect, you are approaching the centre of the universe once more (the edge of the universe has light from the initial big bang or whatever caused the universe, so the edge of the universe should in theory contain light from the inital big bang, which was the centre of the universe). So as you go further away from the center of the universe, your actually approaching the center again. Just a thought of mine 

[UprightMan]

Funnily enough, that's exactly the opinion that I have formed after reading a book...an example I read of this theory is something along the lines of this...

Imagine that a man could only think in two dimensions.  If he were to circumnavigate the globe in a straight line, he would eventually return to the same point.  To him, it would seem that he inexplicably came around to the same point, as he, unable to think in more than 2 dimensions, cannot comprehend the notion of a sphere or anything 3D for that matter.

As with us human beings, we are yet to be able to, visualise in more than three dimensions.  Until we can break this barrier, I doubt we will be able to truly understand the 'shape' of the universe.  Perhaps we will evolve into it, perhaps not.

[Mao]

What do you define as the 'universe'? What is beyond the universe?

[Over9000]

What do you define as the 'universe'? What is beyond the universe?

The universe contains all the super clusters of galaxies, beyond the universe, I believe is going further back in time, before the universe began