The Hubble Ultra Deep Field in 3D

[silverpig]

Originally posted by: nick1985

Originally posted by: RESmonkey
How are the galaxies traveling away from us faster than the speed of light? Isn't that not allowed by special relativity? I haven't studied any of that yet; just read some stuff.

We are moving away from them, and they are moving away from us. Add that speed together and its > light

Think of two people walking away from each other. Sure, both people are just walking, but add those 2 speeds together and its a jog.

That's not how relativity works.

If head away from me at 0.6c and someone else heads away from me in the opposite direction at 0.6c, the combined speed is not 1.2c.

 

[DrPizza]

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[RESmonkey]

Originally posted by: destrekor

Originally posted by: RESmonkey

Originally posted by: destrekor

Originally posted by: silverpig

Originally posted by: Analog
Interesting. However, they claim some galaxies are moving away from us at greater than the speed of light. I thought that to be impossible.

http://www.youtube.com/watch?v=oAVjF_7ensg

It's impossible to have a relative velocity greater than light in space yes, but space is expanding.

that poses an interesting, mind-boggling question:

while nothing can move faster than the speed of light in space, can the expansion of space cause matter to move faster than light?

While it makes sense that two objects moving away from each other, when viewed from one object, would represent movement at faster than light (point a looking at point b, both moving away, by observing from point a makes point b appear to move faster than light away from point a. yes i just repeated, in different terms. no i don't care. )... could it be possible that an object (point A) would remain stationary in terms of relative space, while another object actually moved 'away' at a speed faster than light? Not two objects moving away from each other, but one object moving away from the other, 'on its own', so to speak.
The expansion of space itself, on many levels, at this current point in time, breaks just about every theory we have established, and while 'proving' a few, doesn't help any situation. It completely shatters our elementary understanding of what it is we occupy. So to say we have an absolute grip of astrophysical laws is really perplexing, when we haven't physically observed or proven many of the ones we've established. Most are very well grounded and while nearly impossible to physically prove, observed evidence helps establish those 'rules'. But others, are beyond being pegged 'scientific theories' and are strictly 'theories', because while astrophysicists and mathematicians think they are grand rules, we really don't have the depth and physically observed evidence that would paint the picture clearly.

No because the emitted photons from b would never reach A, IIRC. Then again, I don't know.

Wouldn't it just take longer?

Think of it like a speed limit. Say light can only go 60mph, but two cars are moving in opposite directions at 35mph each. Say it takes one year from the two positions the cars at at for light to reach each other. If they then started moving apart, and Car A began flashing a light at Car B... hmm this is going to require math. I give up. :laugh: But wouldn't Car A's light reach Car B at some point, since both objects on their own are actually moving far less than the speed of light? Their might be a growing distance in between the two, but that's just distance.

The way I look at it, it's not as if light is constantly pulled by the one object moving to the rear of it. At the moment Car A flashes the light, we can immediately forget about Car A, and now focus on the light, which is now moving toward Car B at 60mph, from whatever point in space, while Car B, some years away, is moving forward at barely over half that speed. Eventually the light will catch up.

I guess it could *eventually* reach A. Again, I have not studied any of this. I really want to,t though.

 

[SKORPI0]

Originally posted by: BUTCH1

Originally posted by: Vic
Uh... I didn't say there was any space outside the universe.

Wow, awesome, thanks OP. This begs the question though, If I was in a car traveling at the speed of light and turned on my headlights, what would happen??.

The beam of light will never leave the filaments it is created from or not even be visible at all. Perhaps if you slow down just a little little bit, it should project at a certain length.

 

[silverpig]

Originally posted by: destrekor
It just seems that matter randomly drifting, if not in orbit, would mean something would have to had provided a force of acceleration, and the expansion of space seems to be the only answer in that instance.

So Einstein realized that the universe was filled with matter, and he also knew that matter has gravity. He wondered why the universe hadn't collapsed in on itself due to gravity. He also assumed that the universe was static (ie, not expanding or collapsing), and came up with a force called the "cosmological constant" which counteracted gravity at large scales.

Upon Hubble's measurement of the expansion of the universe, Einstein called his cosmological constant his greatest blunder, and it stemmed from his assumption that the universe was static and unchanging.

The funny thing is, with the realization that the expansion of the universe is accelerating, the inclusion of dark energy to drive this expansion ends up looking a lot like Einstein's cosmological constant.

 

[RESmonkey]

Originally posted by: BUTCH1

Originally posted by: Vic
Uh... I didn't say there was any space outside the universe.

Wow, awesome, thanks OP. This begs the question though, If I was in a car traveling at the speed of light and turned on my headlights, what would happen??.

You can't go that fast.

 

[DrPizza]

Originally posted by: BUTCH1

Originally posted by: Vic
Uh... I didn't say there was any space outside the universe.

Wow, awesome, thanks OP. This begs the question though, If I was in a car traveling at the speed of light and turned on my headlights, what would happen??.

Einstein's theory of special relativity: the speed of light is the same in all inertial frames of reference.

Since your car has mass, it *can't* travel at the speed of light. But let's say that relative to the earth, you were traveling toward the earth at 99.99999999% of the speed of light. (No repeating decimal.) If you turned on your headlights and were able to measure the speed at which they radiated away from you, it would be... <drum roll> The speed of light.

The person on Earth observing the light coming from your spaceship would measure it at... <drum roll> The Speed of Light!

WTF?! There's only one explanation: The river of time is ticking away at two different rates.

 

[RESmonkey]

Originally posted by: DrPizza

Originally posted by: BUTCH1

Originally posted by: Vic
Uh... I didn't say there was any space outside the universe.

Wow, awesome, thanks OP. This begs the question though, If I was in a car traveling at the speed of light and turned on my headlights, what would happen??.

Einstein's theory of special relativity: the speed of light is the same in all inertial frames of reference.

Since your car has mass, it *can't* travel at the speed of light. But let's say that relative to the earth, you were traveling toward the earth at 99.99999999% of the speed of light. (No repeating decimal.) If you turned on your headlights and were able to measure the speed at which they radiated away from you, it would be... <drum roll> The speed of light.

The person on Earth observing the light coming from your spaceship would measure it at... <drum roll> The Speed of Light!

WTF?! There's only one explanation: The river of time is ticking away at two different rates.

In the Earth viewpoint, an observer would see the ship people as SUPPPPPPER slow (almost frozen), and the photons coming from the ship and ship people are still at the speed of light in the frame of Earth, right?

Say I went on a ship and went 99.9999999% lightspeed. I turn on my high beams, and they appear normal.
They appear to be still at light speed since you are rediculously slow at this point (traveling through time) and the .000000001% leftover lightspeed appears to be 100% since your time rate is diff?

 

[destrekor]

Originally posted by: silverpig

Originally posted by: nick1985

Originally posted by: RESmonkey
How are the galaxies traveling away from us faster than the speed of light? Isn't that not allowed by special relativity? I haven't studied any of that yet; just read some stuff.

We are moving away from them, and they are moving away from us. Add that speed together and its > light

Think of two people walking away from each other. Sure, both people are just walking, but add those 2 speeds together and its a jog.

That's not how relativity works.

If head away from me at 0.6c and someone else heads away from me in the opposite direction at 0.6c, the combined speed is not 1.2c.

In terms of relativity, in relation to how light travels, no it isn't 1.2c. But if simply measuring the distance using the speed of light, it would be 1.2c, unless I am greatly misunderstood.

The way I am looking at it, those two objects are moving away from each other. At one measurement point, they are 1 light year away. At another point, they are two lights years away, but in terms of their relative movement, that 2ly distance was reached faster than light would reach that distance.
But specifically regarding the speed of light, no, those objects could never reach distances apart from each other than the speed of light.

The speed of light is often rather confusing, because there are different approaches, determining on how the speed C is being utilized in discussion. It is often used as a means of figuring distance, which is actually unrelated to the speed at which light travels in some instances, such as this.

Think of my analogy a few posts up. And let me expand on that.

Say there are 4 points on a line, not counting 0.

<----4----2----0----2----4---->

Car A and Car B both start at zero. Car A moves towards the left on that line, towards the negative side, at 40mph. Car B moves toward the right, the positive direction, also at 40mph.
In this instance, C, the speed of light, is 60mph.
In total, Car A and Car B are expanding the distance between them faster than C, specifically at 80mph.

Car A reaches point -2, and Car B reaches point 2.
At this point, we'll say they have reached the distance light can travel in a year.

Continuing on, both cars reach their point 4. At this point, they are now 2ly apart, meaning light takes 2 years to reach point -4 if originating from point 4.

In practice, these two objects increased the distance in between them to 2ly total, in less time than light could travel 2ly.

However, neither object traveled faster than C, and neither object could ever escape light from the other object.

 

[PowerEngineer]

Originally posted by: destrekor
The expansion of the universe really just means everything within the universe, all the galaxies, move further away from one another. Thus, space in between the universal bodies expands. But, one way of interpreting the phrase "the expansion of space", and only that phrase, could mean that all of space, even the space within galaxies, would expand. This would most definitely result in the heat death of the universe, but in the end that cannot happen, because all the objects in a galaxy are orbitally tied to one another, the space in between two orbiting bodies should theoretically never expand unless the orbit is not a stable orbit.

I'm not sure why you think the "space within galaxies" is exempt from expansion. My understanding is that expansion of space is supposed to be uniform across all space. It effects over "short" distances, however, is very small and virtually imperceptible when looking at the matter's behavior under the four forces (gravity, electromagnetic, weak nuclear, and strong nuclear). As an example, the small expansion of space inside a nucleus doesn't cause it to split; the strong nuclear forces keep the protons and neutrons pulled together.

 

[BoomerD]

Originally posted by: tranceport
Wow.

I feel so small.

That's what she said too...



Pics like this are pretty humbling...How the fuck can Earth be the ONLY planet in all the universe that could produce life?

 

[Born2bwire]

Originally posted by: coloumb
This proves that WE are at the center of the Universe!

Egocentricity aside, there is no center of the Universe.

 

[PlasmaBomb]

MFL...

 

[PlasmaBomb]

In memory of Plasmabomb's post.

YGPM.

 

[drum]

I can't begin to comprehend the boundaries of space.

 

[Paperdoc]

Mind-boggling stuff, astronomy. From one who does not understand: if some deep space objects appear to be moving away from us faster than the speed of light, how did the light they emitted ever get to us for observation?

Ignoring that question, we are told the light we see today was actually emitted 13 billion years ago. So that's not where those galaxies are - it's where there WERE 13 billion years ago. Where are they now? I presume this is built into the estimates of the current size of the universe, with some estimate of their speed through space over that last 13 billion years.

 

[Nik]

Originally posted by: RESmonkey
How are the galaxies traveling away from us faster than the speed of light? Isn't that not allowed by special relativity? I haven't studied any of that yet; just read some stuff.

take two ends of a rubber band and pull them apart. Each individual end is moving at a certain speed, but the relative departing speed between the two points (ends of the rubber bands) is faster than each individual point's speed.