Faster than light Galaxies

beenthere

Joined Apr 20, 2004
15,819
what if there are two ships coming together 180° apart at 3/4c?
The speed of light is invariant. Ship 1 sees 2 coming at .75 C. Ship 2 sees 1 coming at .75 C. Recall that clocks run slower at relativistic speeds. So, no matter how fast you are traveling, the speed of light is always measured as the same relative to you.

Check out that link I posted on relativistic effects.

I like one illustration I saw in another publication, involving a 30" hole and a meter stick. They are in the same orientation to one another (the hole looks like a circle to the meter stick). They travel in such a way that the meter stick encounters the hole so as to pass through it like being held flat across the hole. The meter stick can fit when it is at the correct speed, as it's length will have contracted just shy of 30".
 
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magnet18

Joined Dec 22, 2010
1,227
I think this explains what Bill Marsden was saying:


Source: Wikipedia = Faster-than-light

An observer may conclude that two objects are moving faster than the speed of light relative to each other, by adding their velocities according to the principle of Galilean relativity.

For example, two fast-moving particles approaching each other from opposite sides of a particle accelerator will appear to be moving at slightly less than twice the speed of light, relative to each other, from the point of view of an observer standing at rest relative to the accelerator. This correctly reflects the rate at which the distance between the two particles is decreasing, from the observer's point of view and is called the closing speed. However, it is not the same as the velocity of one of the particles as would be measured by a hypothetical fast-moving observer traveling alongside the other particle. To obtain this, the calculation must be done according to the principle of special relativity. If the two particles are moving at velocities v and −v, or expressed in units of c, β and −β, where



then this relative velocity (again in units of the speed of light c) is

,

which will always turn out to be less than the speed of light, regardless of the velocities of the two particles.
John
so, at what point must one use this equation instead of adding the velocities like a usual problem??

and beenthere, even though you're moving towards the other one, this becomes irrelevant and it is only seen as moving at 3/4c??
 

jpanhalt

Joined Jan 18, 2008
11,087
The relativistic equations apply at all velocities. However, the correction for relativity (i.e., the v/c component) becomes vanishingly small at low velocities. The result then looks like the classical result, i.e., the collision velocity for two particles with equal and opposite velocities is 2v.

John
 

magnet18

Joined Dec 22, 2010
1,227
All objects with mass travel with a constant "speed" through space-time (It's not really velocity, as velocity is motion over distance, not distance and time). If an object is stationary in relation to its surroundings, it is traveling only through time, at it's constant speed. In fact, the object is traveling through time alone at the speed of light. If the object begins to move, it's speed through space-time remains constant, but it's speed through time must slow down to compensate. If the object moves through space at a speed approaching the speed of light, it's speed through time diminishes significantly. If it moves through space at the speed of light, it will stop "moving" through time altogether.
so if one was to theoretically go faster than light they would go back in time!!
maybe??
 

beenthere

Joined Apr 20, 2004
15,819
Those relativistic effects again..

Approaching C, the length of the vessel shortens , explaining the meter stick trick. But the mass also increases (the current guess about mass involves interaction with Higgs bosons - if your motion involves interaction with more Higgs bosons, then mass increases) to the extent that any particle that makes it to C also has infinite mass. This is bound to be hard on the crew of any spaceship achieving that speed, not to mention the rest of the universe. It's hard to imagine the rocket motor that can accelerate a mass only slightly less than infinite.
 

magnet18

Joined Dec 22, 2010
1,227
I know, I saw that, thats why I said theoretically.
but if you were able to overcome the mass, via Higgs boson / graviton shielding or just by constructing something out of massless particles (I am aware this is completely and utterly impossible), and you passed the speed of light, velocity through time would need to become negative to compensate, correct?
If velocity through space-time is the sum of velocity through space and time...
 

beenthere

Joined Apr 20, 2004
15,819
It's worse than that. The Higgs particle has never been observed, so that theory has yet to get any confirmation. If the LHC can't turn a few up, one of the major underpinnings of the concept of gravity goes in the dumper, and the theoreticians go back to the drawing board. That would affect the understanding of spacetime.
 

magnet18

Joined Dec 22, 2010
1,227
So the theoretical Higgs boson is the theoretical particle for mass, the theoretical graviton is the theoretical particle for gravity...
are there any theories about time particles?
Could they be takions??
that might explain why time slows as we approach c, less interactions with takions similar to the way there is less Higgs boson interaction when stationary...

[/stream of thought]
 

bribri

Joined Feb 20, 2011
143
we were taught this in school, grade 7 or so. i can't remember if it was the teacher, or some AV material... we were told that the universe was expanding, continually increasing in velocity.. the galaxies on the 'outer-rim' (so to speak) would be turning invisible once they get too fast for their light to reach us.
 

magnet18

Joined Dec 22, 2010
1,227
Some of the universe is invisible because the light hasn't had time to reach us yet
http://primaxstudio.com/stuff/scale_of_universe/index.php

and I now take everything any teacher tells me with some skepticism, my 8th grade science teacher told us that transformers make electricity DC so they can send it long distances... we had an argument over that; I ended up staying in her room for lunch.
No matter how right you are a middle schooler cant win an argument with a teacher.

She also told us that electrons go from the positive terminal of a battery to the negative terminal... :mad:

And I noticed looking at the periodic table that unstable atoms all had lower neutron ratios, but she told be that they didn't contribute to stability.

And that wiring three light-bulbs in parallel with a hub is different than daisy chaining them and counted me off!!! :mad:

I WAS FED LIES!!!!!!
[/RANT]
sorry... sore subject for me...
 

beenthere

Joined Apr 20, 2004
15,819
And you wonder why being entertained is more important to most people than doing something significant? In some ways, you learn less in secondary school than grade schoolers did 100 years ago. Education realistically takes supportive parents, competent teachers (both in pedagogy and their subjects) and motivated students.

I had a similarly bad science teacher in the 8th grade. I learned despite the poor instruction. Libraries come in handy.
 

magnet18

Joined Dec 22, 2010
1,227
I had a similarly bad science teacher in the 8th grade. I learned despite the poor instruction. Libraries come in handy.
Library?
whats a library?;)

I was educated by Google.

And yes, it does.
This is why I can't wait to get to college, where there are people who know what they're talking about.

My sister is currently in that teachers class and I'm just waiting for the chance to go chew her out about something.
 

thatoneguy

Joined Feb 19, 2009
6,359
The problem with quantum mechanics is that when it is broken down for most people to understand the concept, important aspects are left out.

Similar issues occur when describing magnetic forces. The removal of "hard math" for the explanation leads an unbelievable number of people to think they can create energy or perpetual motion, based on the analogies they were given.

Those who say "The scientists are snobbish and don't want the information released because of <insert big oil, world domination, etc here>" are those who create complex theories based on rudimentary explanations. When the idea/invention doesn't work, those people rarely try to understand all the details, it's easier to blame others for "lying to them".

The video linked is an example, the math wasn't done correctly, leading to the question in this thread, which has been answered.
 

bribri

Joined Feb 20, 2011
143
i still really like the idea of Tesla's "dynamic theory of gravity"... mainly just because i'm fond of the intuitive feel of gravity conforming to electro-magnetic laws on some level. well, that and the idea of time-machines being way easier to build ; )
 

beenthere

Joined Apr 20, 2004
15,819
it's easier to blame others for "lying to them".
That attitude is why we no longer engage in attempts to convince people that their free energy projects can't possibly work.

They may not know much, but they are quite good at casting blame.
 

Wendy

Joined Mar 24, 2008
23,415
galaxies dont travel at the speed of light, its just the space between them is expanding at a rate that is "faster than the speed of light"
Fraid not, that rule still holds, there is no faster than light with galaxies moving away from Earth. It is the same scenario I mentioned earlier.
 

magnet18

Joined Dec 22, 2010
1,227
The dough represents space itself, and in our expanding Universe space itself is expanding, carrying the galaxies (represented by the raisins) along on a ride.
So the vacuum that is space is expanding??
 

Wendy

Joined Mar 24, 2008
23,415
John, you mean this?

Universe Expands Faster Than Light?

Did the Universe expand faster than light? If not, why does light, up to 12 billion years old, reach us only now? The Universe did not expand faster than light. The Universe was big enough 12 billion years ago that the light from some distant objects is only getting to us now. That doesn't mean that the Universe was more than 12 billion light years wide 12 billion years ago. Because we're moving away from the object, the light has had to catch up to us.
Dr. Eric Christian
 
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