Things you always wanted to know the answer to [Vol. 3]

[Ayahuasca]

GroundEffect said:

1) At speed of light time does not pass, therefore you cannot communicate with another ship as there's no time for the light to travel between the two ships

2) IF however both were at 0.99999c they would communicate between each other with no issue as the relative speeds are zero

2 is true because of relativity - just like a laser between earth and the moon is measured purely in the relative distance and speed, not any absolute speed compared to some fixed point in space or in the galaxy

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

[MartG]

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

[Truckosaurus]

ambuletz said:

Is there some law that means all car seat belt buttons have to be red? ....

Yes. But not in America though: http://jalopnik.com/heres-why-teslas-dont-have-red...

[GroundEffect]

Ayahuasca said:

GroundEffect said:

1) At speed of light time does not pass, therefore you cannot communicate with another ship as there's no time for the light to travel between the two ships

2) IF however both were at 0.99999c they would communicate between each other with no issue as the relative speeds are zero

2 is true because of relativity - just like a laser between earth and the moon is measured purely in the relative distance and speed, not any absolute speed compared to some fixed point in space or in the galaxy

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

As Mart says, this whole thing is about relativity - time dilation & length contraction kicks in and the object traveling at basically-light-speed would appear to be going very very slow and distorted to the observer - therefore never violating relativity.

The jist of the whole thing is: light speed is always constant and its time/distance that much change around it for the universe to hold.

I'm going to stop thinking about this now

[Ayahuasca]

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

[MartG]

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

Because neither of the ships are doing lightspeed, but just under it

[Ayahuasca]

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

Because neither of the ships are doing lightspeed, but just under it

What if they were doing light speed?

[MartG]

Ayahuasca said:

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

Because neither of the ships are doing lightspeed, but just under it

What if they were doing light speed?

They can't

[Ayahuasca]

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

Because neither of the ships are doing lightspeed, but just under it

What if they were doing light speed?

They can't

FFS. What if it was a photon ship, made of photons? Pretty sure they can travel at light speed.

[dudleybloke]

ukaskew said:

How are these big concrete blocks held in place?



I walk directly underneath those blocks on a 23m tower crane every day at the moment to get to my office. My non-engineering brain is uncomfortable with the fact that there is nothing beneath them holding them in place.

On the plus side, if they did let go, I wouldn't feel a thing. Has it ever happened?

https://youtu.be/oMsNynMknD0

[GroundEffect]

Ayahuasca said:

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

Because neither of the ships are doing lightspeed, but just under it

What if they were doing light speed?

They can't

FFS. What if it was a photon ship, made of photons? Pretty sure they can travel at light speed.

Ffs indeed!

I've already answered this! The light never reaches the ship in front because photons don't experience time! There is no time during which anything can travel anywhere, therefore the photon can never catch up. Ever.

Edited by GroundEffect on Tuesday 16th May 22:03

[glazbagun]

Ayahuasca said:

MartG said:

Ayahuasca said:

So a stationery observer would see a beam of light that is traveling at 2x the speed of light?

No he'd see a beam of light travelling at the speed of light, as would an observer on one of the ships - the perception of the shipboard observer being altered by the time dilation effect

In that case how would the light manage to leave the second spacecraft to hit the back of the first one?

Say a fighter plane flying at 500mph behind another plane also flying at 500 mph, and firing a bullet that can travel at a maximum of 500 mph. The bullet can never close the gap. So why can light do it?

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

[zollburgers]

glazbagun said:

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

This video uses a different example but also helps explain the speed of light. It makes sense but is also very strange.

https://www.youtube.com/watch?v=83TF2IBHZ3s

[Ayahuasca]

glazbagun said:

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

What if the guilloutine doors were wired to the same trigger so they had to drop at the same time?

[SilverSixer]

Ayahuasca said:

GroundEffect said:

A problematic hypothetical because nothing with mass can travel at light speed!

Only if you believe Einstein.

And pretty sure I heard the other day that they had discovered a particle that seems to travel faster than light.

Sorry, it was a mistaken observation. The search goes on.

https://en.wikipedia.org/wiki/Faster-than-light_ne...

[SpeckledJim]

Ayahuasca said:

glazbagun said:

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

What if the guilloutine doors were wired to the same trigger so they had to drop at the same time?

I haven't fully understood this, but I think the point is that you can perceive a pair of events happening at the same time but in different places, which another observer perceives as happening at different times - because his 'time' and 'place' are not the same as your 'time' and 'place'.

The only thing the two of you share is the speed of light - the other measurements are 'flexible'.

Edited by SpeckledJim on Wednesday 17th May 10:34

[Ayahuasca]

SpeckledJim said:

Ayahuasca said:

glazbagun said:

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

What if the guilloutine doors were wired to the same trigger so they had to drop at the same time?

I haven't fully understood this, but I think the point is that you can perceive a pair of events happening at the same time but in different places, which another observer perceives as happening at different times - because his 'time' and 'place' are not the same as your 'time' and 'place'.

The only thing the two of you share is the speed of light - the other measurements are 'flexible'.

Edited by SpeckledJim on Wednesday 17th May 10:34

If the electrical signal that triggered the doors was sent at the same time, it would arrive at the doors at the same time (speed of light and all that, kind of) so the doors would close at the same time and the train is either in the tunnel or it is not.

[SpeckledJim]

Ayahuasca said:

SpeckledJim said:

Ayahuasca said:

glazbagun said:

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

What if the guilloutine doors were wired to the same trigger so they had to drop at the same time?

I haven't fully understood this, but I think the point is that you can perceive a pair of events happening at the same time but in different places, which another observer perceives as happening at different times - because his 'time' and 'place' are not the same as your 'time' and 'place'.

The only thing the two of you share is the speed of light - the other measurements are 'flexible'.

Edited by SpeckledJim on Wednesday 17th May 10:34

If the electrical signal that triggered the doors was sent at the same time, it would arrive at the doors at the same time (speed of light and all that, kind of) so the doors would close at the same time and the train is either in the tunnel or it is not.

I think you're falling into the counter-intuitive trap that makes this subject so difficult. You refer to 'the same time' but you mean 'at the same time from my perspective'.

The train has a very different experience of time and space to you - what's true for you may be false for the train. And you're both right.

I wish I had a better handle on this, it's fascinating.

[Halmyre]

Ayahuasca said:

SpeckledJim said:

Ayahuasca said:

glazbagun said:

The speed of light is the constant. It is distance and time itself that changes according to your reference frame. It either speeds up or slows down to allow light to travel at the same speed.

Here's the train in a tunnel at Near Light Speed which will either make you understand or blow your mind and maybe both:

https://www.youtube.com/watch?v=kGsbBw1I0Rg

What if the guilloutine doors were wired to the same trigger so they had to drop at the same time?

I haven't fully understood this, but I think the point is that you can perceive a pair of events happening at the same time but in different places, which another observer perceives as happening at different times - because his 'time' and 'place' are not the same as your 'time' and 'place'.

The only thing the two of you share is the speed of light - the other measurements are 'flexible'.

Edited by SpeckledJim on Wednesday 17th May 10:34

If the electrical signal that triggered the doors was sent at the same time, it would arrive at the doors at the same time (speed of light and all that, kind of) so the doors would close at the same time and the train is either in the tunnel or it is not.

Not if you're on the train.

Bit more explanation here:

https://en.wikipedia.org/wiki/Ladder_paradox

I can cope with that but this really does my head in:

https://en.wikipedia.org/wiki/Ehrenfest_paradox

[Dr Jekyll]

What gets me is the time dilation effect.

Our space travellers head off the Alpha Centuri at close to the speed of light, take a few pictures and head back. When they return several years have passed on Earth but much less for them so they appear younger than expected. Except from their point of view those of us on earth have receded into the distance at close to speed of light then come back, so they expect us to have experienced time dilation.

Apparently time dilation has been demonstrated on a small scale via clocks in spacecraft but the same problem arises. Is it the acceleration that's causing the dilation in this case?