When we view light from a distant galaxy, we do not see that galaxy where it is today, we see that galaxy where it WAS when it emitted the light. The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.

According to many sources, if I am in a rocket ship that accelerates at 1G, and if it continues to accelerate for that rate for close to one year, it will nearly reach the speed of light.
Link: https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/

My question is: If I am traveling at such speeds, and if I send a beam of light from one side of my ship to the other side, will the light travel in a straight line across the room as I see it, or will the light travel in a curved line down toward the floor?

I am emitting light in a direction that is at a right angle to MY direction of movement. Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle to my direction of movement, but in a straight line through space from the original point of emission?

If true, I could mark points on the far wall that would indicate where the light photons will hit when my rocket is moving at different speeds.

Of course, this would only be possible when traveling at a high enough speed so that the trajectory of the photons will measurably change while crossing a room that is only 10 or 20 feet wide.

Any thoughts?

Ed

Ed Lake <detect@outlook.com> wrote:
> When we view light from a distant galaxy, we do not see that galaxy where
> it is today, we see that galaxy where it WAS when it emitted the light.
> The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
>
>
> According to many sources, if I am in a rocket ship that accelerates at
> 1G, and if it continues to accelerate for that rate for close to one
> year, it will nearly reach the speed of light.
> Link:
> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
>
> My question is: If I am traveling at such speeds, and if I send a beam
> of light from one side of my ship to the other side, will the light
> travel in a straight line across the room as I see it, or will the light
> travel in a curved line down toward the floor?

Curved. See Clifford Will’s book “Was Einstein Right?”

It talks a lot about experimental tests of relativity.

>
> I am emitting light in a direction that is at a right angle to MY
> direction of movement. Wouldn’t light travel across the room to a point
> on the wall that is NOT at a right angle to my direction of movement, but
> in a straight line through space from the original point of emission?
>
> If true, I could mark points on the far wall that would indicate where
> the light photons will hit when my rocket is moving at different speeds.
>
> Of course, this would only be possible when traveling at a high enough
> speed so that the trajectory of the photons will measurably change while
> crossing a room that is only 10 or 20 feet wide.
>
> Any thoughts?
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Den 29.03.2022 17:55, skrev Ed Lake:
> When we view light from a distant galaxy, we do not see that galaxy where it is today, we see that galaxy where it WAS when it emitted the light. The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
>
> According to many sources, if I am in a rocket ship that accelerates at 1G, and if it continues to accelerate for that rate for close to one year, it will nearly reach the speed of light.
> Link: https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
>
> My question is: If I am traveling at such speeds, and if I send a beam of light from one side of my ship to the other side, will the light travel in a straight line across the room as I see it, or will the light travel in a curved line down toward the floor?
>
> I am emitting light in a direction that is at a right angle to MY direction of movement. Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle to my direction of movement, but in a straight line through space from the original point of emission?
>
> If true, I could mark points on the far wall that would indicate where the light photons will hit when my rocket is moving at different speeds.
>
> Of course, this would only be possible when traveling at a high enough speed so that the trajectory of the photons will measurably change while crossing a room that is only 10 or 20 feet wide.
>
> Any thoughts?
>
> Ed

Look up Galilean relativity.
When you have learned the relativity of the 17th, 18th.
and 19th centuries, you can start learning the 20th and 21th
centuries relativity.

Think about this question first:

You are in a spaceship with now windows somewhere in
the universe. The ship has no rockets, so it is not
accelerating.
What is your speed?
Can you measure it with instrument inside your ship?

--
Paul

https://paulba.no/

On Tuesday, March 29, 2022 at 8:55:46 AM UTC-7, det...@outlook.com wrote:
> According to many sources, if I am in a rocket ship that accelerates at 1G, and if it
> continues to accelerate for that rate for close to one year, it will nearly reach the
> speed of light. My question is: If I am traveling at such speeds, and if I send a beam
> of light from one side of my ship to the other side, will the light travel in a straight
> line across the room as I see it, or will the light travel in a curved line down toward
> the floor?

It's essential to distinguish between velocity and acceleration (rate of change of velocity). You mentioned that the ship is undergoing 1g of proper acceleration. This is what determines the amount of deflection ("downward curving") of a light pulse, i.e., you will find the same amount of deflection that you would find in a room stationary on the Earths surface, experiencing 1g of gravity. Note that the amount of deflection relative to your rocket depends only on the proper acceleration, not on the velocity. In other words, if you maintain 1 g of proper acceleration from the beginning (when you start with 0 velocity) to one year later (when your velocity relative to the earth is nearly c), you will always find the same deflection inside your rocket.

> I am emitting light in a direction that is at a right angle to MY direction of movement.
> Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle
> to my direction of movement, but in a straight line through space from the original
> point of emission?

The pulse will follow a straight path in terms of any system of inertial coordinates, though of course your accelerating space ship is not at rest in any such system, which is why you have the deflection in the ship. Also, note that the direction of the pulse is at right angles to the direction of the ship only in terms of one particular system of inertial coordinates, not in terms of others, because of the effect of aberration.

> If true, I could mark points on the far wall that would indicate where the light photons
> will hit when my rocket is moving at different speeds.

By this method you are measuring the acceleration (rate of change of velocity), not the velocity. This is precisely how many modern navigational devices work, using lasers to measure rotational or longitudinal acceleration. Of course, we can then use dead reckoning to integrate our velocity and positions relative to our original location and state of motion.

On Tuesday, March 29, 2022 at 1:08:41 PM UTC-5, bodk...@gmail.com wrote:
> Ed Lake wrote:
> > When we view light from a distant galaxy, we do not see that galaxy where
> > it is today, we see that galaxy where it WAS when it emitted the light.
> > The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
> >
> >
> > According to many sources, if I am in a rocket ship that accelerates at
> > 1G, and if it continues to accelerate for that rate for close to one
> > year, it will nearly reach the speed of light.
> > Link:
> > https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
> >
> > My question is: If I am traveling at such speeds, and if I send a beam
> > of light from one side of my ship to the other side, will the light
> > travel in a straight line across the room as I see it, or will the light
> > travel in a curved line down toward the floor?
> Curved. See Clifford Will’s book “Was Einstein Right?”

Ah! Okay. At long last we agree on something.

Ed

On Tuesday, March 29, 2022 at 1:13:27 PM UTC-5, Paul B. Andersen wrote:
> Den 29.03.2022 17:55, skrev Ed Lake:
> > When we view light from a distant galaxy, we do not see that galaxy where it is today, we see that galaxy where it WAS when it emitted the light. The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
> >
> > According to many sources, if I am in a rocket ship that accelerates at 1G, and if it continues to accelerate for that rate for close to one year, it will nearly reach the speed of light.
> > Link: https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
> >
> > My question is: If I am traveling at such speeds, and if I send a beam of light from one side of my ship to the other side, will the light travel in a straight line across the room as I see it, or will the light travel in a curved line down toward the floor?
> >
> > I am emitting light in a direction that is at a right angle to MY direction of movement. Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle to my direction of movement, but in a straight line through space from the original point of emission?
> >
> > If true, I could mark points on the far wall that would indicate where the light photons will hit when my rocket is moving at different speeds.
> >
> > Of course, this would only be possible when traveling at a high enough speed so that the trajectory of the photons will measurably change while crossing a room that is only 10 or 20 feet wide.
> >
> > Any thoughts?
> >
> > Ed
> Look up Galilean relativity.
> When you have learned the relativity of the 17th, 18th.
> and 19th centuries, you can start learning the 20th and 21th
> centuries relativity.
>
> Think about this question first:
>
> You are in a spaceship with no windows somewhere in
> the universe. The ship has no rockets, so it is not
> accelerating.
> What is your speed?
> Can you measure it with instrument inside your ship?

Supposedly not. But the real question is: Does a photon ALWAYS travel
in a straight line away from the emitting atom, or can it also travel sideways
if the emitting atom is traveling sideways?
I've seen no reason to believe a photon can travel sideways.

If it can't also travel sideways, then why would a photon travel in a straight line
from wall to wall even when the ship is NOT accelerating?

I'm not advocating anything here. I'm just trying to figure out why you CAN'T
measure your speed (in theory) even when not accelerating. In practice, of
course, light would travel across a room so fast that there is no way to measure
whether it traveled in a straight line or not.

Ed

Ed Lake <detect@outlook.com> wrote:
> On Tuesday, March 29, 2022 at 1:08:41 PM UTC-5, bodk...@gmail.com wrote:
>> Ed Lake wrote:
>>> When we view light from a distant galaxy, we do not see that galaxy where
>>> it is today, we see that galaxy where it WAS when it emitted the light.
>>> The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
>>>
>>>
>>> According to many sources, if I am in a rocket ship that accelerates at
>>> 1G, and if it continues to accelerate for that rate for close to one
>>> year, it will nearly reach the speed of light.
>>> Link:
>>> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
>>>
>>>
>>> My question is: If I am traveling at such speeds, and if I send a beam
>>> of light from one side of my ship to the other side, will the light
>>> travel in a straight line across the room as I see it, or will the light
>>> travel in a curved line down toward the floor?
>> Curved. See Clifford Will’s book “Was Einstein Right?”
>
> Ah! Okay. At long last we agree on something.
>
> Ed
>

Well, the key thing here, Ed, as I said before, is that it’s better if you
abstain from forming a strong opinion about the answer until you learn
something about it first.

Otherwise your habit is to form a strong opinion first, then to mine small
soundbites that support your strong opinion, and to declare other things
wrong.

--
Odd Bodkin -- maker of fine toys, tools, tables

On Tuesday, March 29, 2022 at 1:50:20 PM UTC-5, Townes Olson wrote:
> On Tuesday, March 29, 2022 at 8:55:46 AM UTC-7, wrote:
> > According to many sources, if I am in a rocket ship that accelerates at 1G, and if it
> > continues to accelerate for that rate for close to one year, it will nearly reach the
> > speed of light. My question is: If I am traveling at such speeds, and if I send a beam
> > of light from one side of my ship to the other side, will the light travel in a straight
> > line across the room as I see it, or will the light travel in a curved line down toward
> > the floor?
> It's essential to distinguish between velocity and acceleration (rate of change of velocity). You mentioned that the ship is undergoing 1g of proper acceleration. This is what determines the amount of deflection ("downward curving") of a light pulse, i.e., you will find the same amount of deflection that you would find in a room stationary on the Earths surface, experiencing 1g of gravity. Note that the amount of deflection relative to your rocket depends only on the proper acceleration, not on the velocity. In other words, if you maintain 1 g of proper acceleration from the beginning (when you start with 0 velocity) to one year later (when your velocity relative to the earth is nearly c), you will always find the same deflection inside your rocket.

Actually, the question doesn't seem to have anything to do with velocity OR
acceleration. The only real question seems to be: Does a photon ALWAYS travel in a
straight line away from the POINT IN SPACE where the atom EMITTED the photon
EVEN WHEN the atom is moving at some angle?

> > I am emitting light in a direction that is at a right angle to MY direction of movement.
> > Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle
> > to my direction of movement, but in a straight line through space from the original
> > point of emission?
> The pulse will follow a straight path in terms of any system of inertial coordinates, though of course your accelerating space ship is not at rest in any such system, which is why you have the deflection in the ship. Also, note that the direction of the pulse is at right angles to the direction of the ship only in terms of one particular system of inertial coordinates, not in terms of others, because of the effect of aberration.

The "system of inertial coordinates" appears to begin at the atom that emitted the
photon AT THE INSTANT the photon was emitted. The atom then goes in one direction
while the photon travels at a right angle to where the atom WAS.

> > If true, I could mark points on the far wall that would indicate where the light photons
> > will hit when my rocket is moving at different speeds.
> By this method you are measuring the acceleration (rate of change of velocity), not the velocity. This is precisely how many modern navigational devices work, using lasers to measure rotational or longitudinal acceleration. Of course, we can then use dead reckoning to integrate our velocity and positions relative to our original location and state of motion.

I would think that if "modern navigational devices" measure acceleration, they measure it
the way radar guns do, by measuring a change in frequencies caused by velocity time dilation.
But, I could be wrong.

Ed

On Tuesday, March 29, 2022 at 2:53:51 PM UTC-5, bodk...@gmail.com wrote:
> Ed Lake wrote:
> > On Tuesday, March 29, 2022 at 1:08:41 PM UTC-5, bodk...@gmail.com wrote:
> >> Ed Lake wrote:
> >>> When we view light from a distant galaxy, we do not see that galaxy where
> >>> it is today, we see that galaxy where it WAS when it emitted the light.
> >>> The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
> >>>
> >>>
> >>> According to many sources, if I am in a rocket ship that accelerates at
> >>> 1G, and if it continues to accelerate for that rate for close to one
> >>> year, it will nearly reach the speed of light.
> >>> Link:
> >>> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
> >>>
> >>>
> >>> My question is: If I am traveling at such speeds, and if I send a beam
> >>> of light from one side of my ship to the other side, will the light
> >>> travel in a straight line across the room as I see it, or will the light
> >>> travel in a curved line down toward the floor?
> >> Curved. See Clifford Will’s book “Was Einstein Right?”
> >
> > Ah! Okay. At long last we agree on something.
> >
> > Ed
> >
> Well, the key thing here, Ed, as I said before, is that it’s better if you
> abstain from forming a strong opinion about the answer until you learn
> something about it first.
>
> Otherwise your habit is to form a strong opinion first, then to mine small
> soundbites that support your strong opinion, and to declare other things
> wrong.

Actually, I don't think I have any "strong opinions" about physics. I think I
just look at the facts and evidence. If the facts and evidence indicate that
something is true, I'll stick with what seems to be true. It's not an opinion,
it is just what seems to be true based upon the facts and evidence. NEW
FACTS could INSTANTLY change my evaluation of the facts and evidence.

Personal attacks won't change anything.

Ed

Ed Lake <detect@outlook.com> wrote:
> On Tuesday, March 29, 2022 at 1:50:20 PM UTC-5, Townes Olson wrote:
>> On Tuesday, March 29, 2022 at 8:55:46 AM UTC-7, wrote:
>>> According to many sources, if I am in a rocket ship that accelerates at 1G, and if it
>>> continues to accelerate for that rate for close to one year, it will nearly reach the
>>> speed of light. My question is: If I am traveling at such speeds, and if I send a beam
>>> of light from one side of my ship to the other side, will the light travel in a straight
>>> line across the room as I see it, or will the light travel in a curved line down toward
>>> the floor?
>> It's essential to distinguish between velocity and acceleration (rate of
>> change of velocity). You mentioned that the ship is undergoing 1g of
>> proper acceleration. This is what determines the amount of deflection
>> ("downward curving") of a light pulse, i.e., you will find the same
>> amount of deflection that you would find in a room stationary on the
>> Earths surface, experiencing 1g of gravity. Note that the amount of
>> deflection relative to your rocket depends only on the proper
>> acceleration, not on the velocity. In other words, if you maintain 1 g
>> of proper acceleration from the beginning (when you start with 0
>> velocity) to one year later (when your velocity relative to the earth is
>> nearly c), you will always find the same deflection inside your rocket.
>
> Actually, the question doesn't seem to have anything to do with velocity OR
> acceleration. The only real question seems to be: Does a photon ALWAYS travel in a
> straight line away from the POINT IN SPACE where the atom EMITTED the photon
> EVEN WHEN the atom is moving at some angle?

If you had an accelerating rocket ship and you had a bunch of equally
spaced sheets of paper between the source and the wall, and you punched
holes in the cardboard sheets where you saw a spot, until the beam could
travel all the way to the wall, then the succession of holes would not be
something you could pass a straight broomstick through.

>
>>> I am emitting light in a direction that is at a right angle to MY direction of movement.
>>> Wouldn’t light travel across the room to a point on the wall that is
>>> NOT at a right angle
>>> to my direction of movement, but in a
>>> straight line through space from the original
>>> point of emission?
>> The pulse will follow a straight path in terms of any system of inertial
>> coordinates, though of course your accelerating space ship is not at
>> rest in any such system, which is why you have the deflection in the
>> ship. Also, note that the direction of the pulse is at right angles to
>> the direction of the ship only in terms of one particular system of
>> inertial coordinates, not in terms of others, because of the effect of aberration.
>
> The "system of inertial coordinates" appears to begin at the atom that emitted the
> photon AT THE INSTANT the photon was emitted. The atom then goes in one direction
> while the photon travels at a right angle to where the atom WAS.
>
>>> If true, I could mark points on the far wall that would indicate where the light photons
>>> will hit when my rocket is moving at different speeds.
>> By this method you are measuring the acceleration (rate of change of
>> velocity), not the velocity. This is precisely how many modern
>> navigational devices work, using lasers to measure rotational or
>> longitudinal acceleration. Of course, we can then use dead reckoning to
>> integrate our velocity and positions relative to our original location
>> and state of motion.
>
> I would think that if "modern navigational devices" measure acceleration, they measure it
> the way radar guns do, by measuring a change in frequencies caused by
> velocity time dilation.
> But, I could be wrong.
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Ed Lake <detect@outlook.com> wrote:
> On Tuesday, March 29, 2022 at 2:53:51 PM UTC-5, bodk...@gmail.com wrote:
>> Ed Lake wrote:
>>> On Tuesday, March 29, 2022 at 1:08:41 PM UTC-5, bodk...@gmail.com wrote:
>>>> Ed Lake wrote:
>>>>> When we view light from a distant galaxy, we do not see that galaxy where
>>>>> it is today, we see that galaxy where it WAS when it emitted the light.
>>>>> The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
>>>>>
>>>>>
>>>>> According to many sources, if I am in a rocket ship that accelerates at
>>>>> 1G, and if it continues to accelerate for that rate for close to one
>>>>> year, it will nearly reach the speed of light.
>>>>> Link:
>>>>> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
>>>>>
>>>>>
>>>>>
>>>>> My question is: If I am traveling at such speeds, and if I send a beam
>>>>> of light from one side of my ship to the other side, will the light
>>>>> travel in a straight line across the room as I see it, or will the light
>>>>> travel in a curved line down toward the floor?
>>>> Curved. See Clifford Will’s book “Was Einstein Right?”
>>>
>>> Ah! Okay. At long last we agree on something.
>>>
>>> Ed
>>>
>> Well, the key thing here, Ed, as I said before, is that it’s better if you
>> abstain from forming a strong opinion about the answer until you learn
>> something about it first.
>>
>> Otherwise your habit is to form a strong opinion first, then to mine small
>> soundbites that support your strong opinion, and to declare other things
>> wrong.
>
> Actually, I don't think I have any "strong opinions" about physics. I think I
> just look at the facts and evidence.

Frankly, Ed, your history doesn’t suggest that.

What you do is form an opinion based on what makes common sense to you.
Then you look at the evidence, and selectively categorize evidence
according to whether it agrees with your common sense or not. That which
doesn’t, you call wrong or misinterpreted.

> If the facts and evidence indicate that
> something is true, I'll stick with what seems to be true. It's not an opinion,
> it is just what seems to be true based upon the facts and evidence. NEW
> FACTS could INSTANTLY change my evaluation of the facts and evidence.
>
> Personal attacks won't change anything.
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On 3/29/22 10:55 AM, Ed Lake wrote:
> When we view light from a distant galaxy, we do not see that galaxy
> where it is today, we see that galaxy where it WAS when it emitted
> the light. The light traveled in a STRAIGHT LINE from POINT OF
> EMISSION to me.

Actually it follows a null geodesic through spacetime. Gravitational
lensing conclusively demonstrates this -- there are many instances
of observing multiple images of a single distant quasar or galaxy, so
the light trajectories cannot possibly be "straight".

> According to many sources, if I am in a rocket ship that accelerates
> at 1G, and if it continues to accelerate for that rate for close to
> one year, it will nearly reach the speed of light. Link:
> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/

As always, you MUST specify the coordinates relative to which you
measure a speed (or velocity). Ditto for an acceleration and a duration.

Note it simply is not possible to accelerate at 1g (=9.8m/s^2) relative
to an inertial frame for a year, even in a gedanken. But rockets are
usually specified by their PROPER acceleration. If a rocket started from
rest in an inertial frame and had a proper acceleration of 1g for a year
(either in that frame or elapsed proper time), it would indeed approach
speed c relative to that frame.

When considering relativistic speeds like this, one must evaluate the
accuracy of an inertial frame over such large distances and times. In
this case, if the ship started from earth, the ICRF would remain an
accurately-inertial reference frame, as the rocket never approaches any
star. But not necessarily for 10 years....

> My question is: If I am traveling at such speeds, and if I send a
> beam of light from one side of my ship to the other side, will the
> light travel in a straight line across the room as I see it, or will
> the light travel in a curved line down toward the floor?

As usual, your words are ambiguous. You REALLY need to learn how to ask
a specific, self-consistent question. Of course to be able to do that
you would have to understand some basic physics, which you have
repeatedly refused to do.

"At such speeds" kind of implies you are no longer considering the
acceleration. If the rocket ceased accelerating after a year, and you
then do this, the light beam will traverse the ship in a straight line
(measured relative to the rocket's inertial frame).

But that implication is not necessarily what you meant, and "floor"
implies it keeps accelerating. If the rocket is still accelerating at 1g
when you to this, then the light beam will traverse the ship in a
parabola (measured relative to the rocket's locally inertial frame).
This applies at all times during the acceleration, not just after one
year; the spot position on the far wall depends on the proper
acceleration, not time or speed relative to anything. This assumes that
the laser is affixed to its wall with sufficient rigidity so it does not
rotate relative to the ship, and the far wall is similarly rigid.

Note it is not possible to accurately measure the difference between a
straight line and that parabola, unless you can measure the difference
between acceleration on and off -- in that case, if the ship is 10
meters wide then the difference would be ~5E-15 meters; even ignoring
the impossibility of measuring a laser spot position to such accuracy,
with current technology that is not possible to measure [#].

[#] Today the highest-resolution measurement of distance
is ~1E-12 meters, which just happens to be in our
Precision Laser Metrology Lab at IIT.

> I am emitting light in a direction that is at a right angle to MY
> direction of movement.

Not really. You are implicitly assuming some sort of "absolute motion",
which is invalid.

> Wouldn’t light travel across the room to a point on the wall that is
> NOT at a right angle to my direction of movement, but in a straight
> line through space from the original point of emission?

I must guess what you are trying to say. My interpretation of your words
means the answer is: No. In particular, the laser is affixed to the
ship, not somewhere in "space" (whatever you mean by that).

> If true, I could mark points on the far wall that would indicate
> where the light photons will hit when my rocket is moving at
> different speeds.

Nope. The position of the light beam at the other wall depends on the
ship's proper acceleration, not its velocity (relative to anything). And
for the difference to be measurable in a 10-meter-wide spaceship the
acceleration would need to be far too great for humans to survive.

A simple spring scale with a calibrated weight would measure such a
ship's proper acceleration vastly better than the position of a laser
spot on the opposite wall.

> [... further nonsense ignored]

Tom Roberts

On Tuesday, March 29, 2022 at 4:01:44 PM UTC-4, det...@outlook.com wrote:
> The only real question seems to be: Does a photon ALWAYS travel in a
> straight line away from the POINT IN SPACE where the atom EMITTED the photon

Now, that's a 'good' question for you to ponder.

The only way to know, is to test it, in many environments. Luckily, past and present physicists have done that.
Their conclusion: sometimes it goes in a straight line, sometimes it doesn't.
But this is what they have noticed in every case: if the Observer (his reference frame) was an inertial one, the photons always travel in a straight line. If however is reference frame was not an inertial one, the photon typically did travel in a straight line.

SR/GR say/models the above by using equations.

On Tuesday, March 29, 2022 at 1:01:44 PM UTC-7, det...@outlook.com wrote:
> > > According to many sources, if I am in a rocket ship that accelerates at 1G, and if it
> > > continues to accelerate for that rate for close to one year, it will nearly reach the
> > > speed of light. My question is: If I am traveling at such speeds, and if I send a beam
> > > of light from one side of my ship to the other side, will the light travel in a straight
> > > line across the room as I see it, or will the light travel in a curved line down toward
> > > the floor?
> > It's essential to distinguish between velocity and acceleration (rate of change of velocity). You mentioned that the ship is undergoing 1g of proper acceleration. This is what determines the amount of deflection ("downward curving") of a light pulse, i.e., you will find the same amount of deflection that you would find in a room stationary on the Earths surface, experiencing 1g of gravity. Note that the amount of deflection relative to your rocket depends only on the proper acceleration, not on the velocity. In other words, if you maintain 1 g of proper acceleration from the beginning (when you start with 0 velocity) to one year later (when your velocity relative to the earth is nearly c), you will always find the same deflection inside your rocket.
>
> The question doesn't seem to have anything to do with velocity OR acceleration.

The question said "a rocket ship accelerates at 1G..." and "traveling at such speeds...", so I don't understand what you mean when you say the question had nothing to do with velocity or acceleration.

To re-iterate, the "curving" that you asked about is due to the proper acceleration, not to velocity, but the aberration that implies the path is not perpendicular to the rocket's axis is due to velocity, not acceleration. Also, bear in mind that the rocket could (in principle) maintain constant proper acceleration, but it's acceleration in terms of (say) the Earth's inertial coordinate system will asymptotically approach zero as its speed approaches c.

> Does a photon ALWAYS travel in a straight line away from the POINT IN SPACE
> where the atom EMITTED the photon EVEN WHEN the atom is moving at some angle?

It's essential to distinguish between curving paths versus aberration. Neglecting the effects of quantum uncertainty, a photon propagates in a straight line in terms of any local system of inertial coordinates, though not in terms of accelerating coordinates (such as those in which your accelerating rocket is at rest), and not in terms of a global coordinate system in the presence of gravity. In contrast, the angle that a photon's path makes with the rocket's axis depends on the system of inertial coordinates, because of aberration, but the path is still straight, it's just the angle that is dependent on the coordinate system.

> The "system of inertial coordinates" appears to begin at the atom that emitted the
> photon AT THE INSTANT the photon was emitted. The atom then goes in one direction
> while the photon travels at a right angle to where the atom WAS.

Again, the angle between the path of a photon and the axis of the rocket depends on the system of inertial coordinates in which you express that angle.. This is called aberration, and has always been part of physics (discovered in 1727), although the relativistic expression for aberration is different to account for the relativity of simultaneity. But don't confuse this with the curving of paths in terms of accelerating coordinates (e.g., in your rocket), nor with the curving of paths in a gravitational field.

By the way, there's no need to put "system of inertial coordinates" in quotation marks. It is a perfectly objective and well defined system of measure, as given by a grid of standard rulers with clocks inertially synchronized at each node. These are the coordinate systems in terms of which the laws of physics take their simple homogeneous and isotropic form, so they are very important and physically meaningful.

> I would think that if "modern navigational devices" measure acceleration....

Again, no need for quotation marks. Accelerometers and ring laser gyroscopes, etc., are commonplace. These are used in most modern navigation devices, although there are still some mechanical gyros and accelerometers in use. Same principle of operation.

> they measure it the way radar guns do, by measuring a change in frequencies
> caused by velocity time dilation.

It's possible to measure the rate of change of distance to some other object using radar, giving the relative velocity, but navigation devices are intended to measure *absolute* acceleration, not the relative velocity or acceleration between the device and some other arbitrary object.

On Tuesday, 29 March 2022 at 20:13:27 UTC+2, Paul B. Andersen wrote:
> Den 29.03.2022 17:55, skrev Ed Lake:
> > When we view light from a distant galaxy, we do not see that galaxy where it is today, we see that galaxy where it WAS when it emitted the light. The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
> >
> > According to many sources, if I am in a rocket ship that accelerates at 1G, and if it continues to accelerate for that rate for close to one year, it will nearly reach the speed of light.
> > Link: https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
> >
> > My question is: If I am traveling at such speeds, and if I send a beam of light from one side of my ship to the other side, will the light travel in a straight line across the room as I see it, or will the light travel in a curved line down toward the floor?
> >
> > I am emitting light in a direction that is at a right angle to MY direction of movement. Wouldn’t light travel across the room to a point on the wall that is NOT at a right angle to my direction of movement, but in a straight line through space from the original point of emission?
> >
> > If true, I could mark points on the far wall that would indicate where the light photons will hit when my rocket is moving at different speeds.
> >
> > Of course, this would only be possible when traveling at a high enough speed so that the trajectory of the photons will measurably change while crossing a room that is only 10 or 20 feet wide.
> >
> > Any thoughts?
> >
> > Ed
> Look up Galilean relativity.

All people on Earth must observe and claim, that Sun is rotating
around! That's what The Laws of Nature are!!!

On Tuesday, 29 March 2022 at 22:57:02 UTC+2, bodk...@gmail.com wrote:
> Ed Lake <det...@outlook.com> wrote:
> > On Tuesday, March 29, 2022 at 2:53:51 PM UTC-5, bodk...@gmail.com wrote:
> >> Ed Lake wrote:
> >>> On Tuesday, March 29, 2022 at 1:08:41 PM UTC-5, bodk...@gmail.com wrote:
> >>>> Ed Lake wrote:
> >>>>> When we view light from a distant galaxy, we do not see that galaxy where
> >>>>> it is today, we see that galaxy where it WAS when it emitted the light.
> >>>>> The light traveled in a STRAIGHT LINE from POINT OF EMISSION to me.
> >>>>>
> >>>>>
> >>>>> According to many sources, if I am in a rocket ship that accelerates at
> >>>>> 1G, and if it continues to accelerate for that rate for close to one
> >>>>> year, it will nearly reach the speed of light.
> >>>>> Link:
> >>>>> https://www.technologyreview.com/2020/01/10/238139/can-constant-acceleration-be-used-to-produce-artificial-gravity-in-space/
> >>>>>
> >>>>>
> >>>>>
> >>>>> My question is: If I am traveling at such speeds, and if I send a beam
> >>>>> of light from one side of my ship to the other side, will the light
> >>>>> travel in a straight line across the room as I see it, or will the light
> >>>>> travel in a curved line down toward the floor?
> >>>> Curved. See Clifford Will’s book “Was Einstein Right?”
> >>>
> >>> Ah! Okay. At long last we agree on something.
> >>>
> >>> Ed
> >>>
> >> Well, the key thing here, Ed, as I said before, is that it’s better if you
> >> abstain from forming a strong opinion about the answer until you learn
> >> something about it first.
> >>
> >> Otherwise your habit is to form a strong opinion first, then to mine small
> >> soundbites that support your strong opinion, and to declare other things
> >> wrong.
> >
> > Actually, I don't think I have any "strong opinions" about physics. I think I
> > just look at the facts and evidence.
> Frankly, Ed, your history doesn’t suggest that.
>
> What you do is form an opinion based on what makes common sense to you.
> Then you look at the evidence, and selectively categorize evidence

And see, that forbidden by insane relativistic
maniacs TAI keep measuring t'=t, just like
all serious clocks always did.

On Tuesday, 29 March 2022 at 23:27:38 UTC+2, tjrob137 wrote:
> On 3/29/22 10:55 AM, Ed Lake wrote:
> > When we view light from a distant galaxy, we do not see that galaxy
> > where it is today, we see that galaxy where it WAS when it emitted
> > the light. The light traveled in a STRAIGHT LINE from POINT OF
> > EMISSION to me.
> Actually it follows a null geodesic through spacetime. Gravitational
> lensing conclusively demonstrates this -- there are many instances
> of observing multiple images of a single distant quasar or galaxy, so
> the light trajectories cannot possibly be "straight".

Tom, poor idiot, have you ever heard of non euclidean
geometries? Oh, yes, it can, and that's one of the main
assumptions of your idiot guru.

As always, the problem is that most people here cannot discuss reality.
They only understand mathematics.

It’s a demonstration of Einstein’s famous quote: ““As far as the laws of
mathematics refer to reality, they are not certain; and as far as they are
certain, they do not refer to reality.”

My question is very simple: If I am traveling through space, away from
the Earth and toward Alpha Centauri, will a light photon that I emit at a
right angle to my direction of travel continue to move at a right angle to
me, or will it move at a right angle to the point where the photon was emitted?

The answer seems obvious: The photon will move away from the point
where it was emitted, not away from me.

And it doesn’t make any difference if I emit the photon while accelerating
or while coasting. The photon will move away from the point where it
was emitted, not away from me.

Yes, I know that the photon may eventually change its trajectory if it passes
through or near some massive galaxy, but that has nothing to do with the
question. It’s just a way to create an argument instead of answering the
question. And you can also create arguments about what words I use, but
that’s just another way to avoid answering the question.

Ed

On 3/30/2022 10:51 AM, Ed Lake wrote:

> My question is very simple: If I am traveling through space, away from
> the Earth and toward Alpha Centauri, will a light photon that I emit at a
> right angle to my direction of travel continue to move at a right angle to
> me, or will it move at a right angle to the point where the photon was emitted?

In which frame? That of the spaceship or of Earth (or Alpha Centauri)?
Since I already know you don't understand the concept of frames in
physics, I don't expect a rational answer to this, or a rational
response to anyone who answers you.
>
> The answer seems obvious: The photon will move away from the point
> where it was emitted, not away from me.

Did you do the special relativity math to work out the answer? Oh that's
right, "mathematicians" are your boogeymen so math is the incantation of
evil.

On Wednesday, March 30, 2022 at 7:51:14 AM UTC-7, det...@outlook.com wrote:

> My question is very simple: If I am traveling through space, away from
> the Earth and toward Alpha Centauri, will a light photon that I emit at a
> right angle to my direction of travel continue to move at a right angle to
> me, or will it move at a right angle to the point where the photon was emitted?
>
> The answer seems obvious: The photon will move away from the point
> where it was emitted, not away from me.
>

Imbecile,

In the frame of the rocket, the photon will not move at a right angle wrt the wall of the rocket.
In the frame of the Earth, the photon will move at a right angle wrt the wall of the rocket

I do not expect you to EVER get the above.

On Wednesday, March 30, 2022 at 11:05:59 AM UTC-5, Michael Moroney wrote:
> On 3/30/2022 10:51 AM, Ed Lake wrote:
>
> > My question is very simple: If I am traveling through space, away from
> > the Earth and toward Alpha Centauri, will a light photon that I emit at a
> > right angle to my direction of travel continue to move at a right angle to
> > me, or will it move at a right angle to the point where the photon was emitted?
> In which frame? That of the spaceship or of Earth (or Alpha Centauri)?
> Since I already know you don't understand the concept of frames in
> physics, I don't expect a rational answer to this, or a rational
> response to anyone who answers you.
> >
> > The answer seems obvious: The photon will move away from the point
> > where it was emitted, not away from me.
> Did you do the special relativity math to work out the answer? Oh that's
> right, "mathematicians" are your boogeymen so math is the incantation of
> evil.

No, it just clouds the issue. It is as Einstein once said, "“As far as the laws of
mathematics refer to reality, they are not certain; and as far as they are certain,
they do not refer to reality.”

I'm trying to discuss reality, and all you can understand is mathematics.

Using different frames of reference will just give different answers.
The question is about REALITY. In REALITY, the photon moves away from
the POINT where it was emitted by an atom. Once the atom has moved
on, there is nothing at that point. There is just a photon moving through
empty space. And mathematicians cannot comprehend an object
moving through empty space. They REQUIRE that ALL OBJECTS move
relative to some other object. But the photon is not moving relative to any object.

Ed

Ed Lake <detect@outlook.com> wrote:
> On Wednesday, March 30, 2022 at 11:05:59 AM UTC-5, Michael Moroney wrote:
>> On 3/30/2022 10:51 AM, Ed Lake wrote:
>>
>>> My question is very simple: If I am traveling through space, away from
>>> the Earth and toward Alpha Centauri, will a light photon that I emit at a
>>> right angle to my direction of travel continue to move at a right angle to
>>> me, or will it move at a right angle to the point where the photon was emitted?
>> In which frame? That of the spaceship or of Earth (or Alpha Centauri)?
>> Since I already know you don't understand the concept of frames in
>> physics, I don't expect a rational answer to this, or a rational
>> response to anyone who answers you.
>>>
>>> The answer seems obvious: The photon will move away from the point
>>> where it was emitted, not away from me.
>> Did you do the special relativity math to work out the answer? Oh that's
>> right, "mathematicians" are your boogeymen so math is the incantation of
>> evil.
>
> No, it just clouds the issue.

For you. Not for people who are mathematically literate.

And just to remind you, mathematical literacy is not confined to
mathematicians, though you’d live to partition them off,

Mathematical literacy is something that is expected of anyone in a wide
variety of fields ranging from chemistry to medicine to economics.

You are mathematically illiterate and this is a debilitating disadvantage
in discussing any of a wide number of topics, including this one.

> It is as Einstein once said, "“As far as the laws of
> mathematics refer to reality, they are not certain; and as far as they are certain,
> they do not refer to reality.”
>
> I'm trying to discuss reality, and all you can understand is mathematics.
>
> Using different frames of reference will just give different answers.
> The question is about REALITY. In REALITY, the photon moves away from
> the POINT where it was emitted by an atom. Once the atom has moved
> on, there is nothing at that point. There is just a photon moving through
> empty space. And mathematicians cannot comprehend an object
> moving through empty space. They REQUIRE that ALL OBJECTS move
> relative to some other object. But the photon is not moving relative to any object.
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On Wednesday, 30 March 2022 at 19:03:20 UTC+2, bodk...@gmail.com wrote:

> For you. Not for people who are mathematically literate.
>
> And just to remind you, mathematical literacy is not confined to
> mathematicians, though you’d live to partition them off,

Speaking of mathematics, it's always good to remind
that your bunch of idiots had to announce its oldest, very
important and successful part false, as it didn't want to
cooperate with your madness.

On Wednesday, March 30, 2022 at 7:51:14 AM UTC-7, det...@outlook.com wrote:
> If I am traveling through space, away from the Earth and toward Alpha
> Centauri, will a light photon that I emit at a right angle to my direction of
> travel continue to move at a right angle to me...

Yes, if you are not accelerating, then in terms of your co-moving inertial reference system the pulse of light will propagate in a straight line in whatever direction you emitted it. So, if you emitted it perpendicular to the rocket axis in terms of your co-moving inertial system of reference, it will continue to move in that direction at speed c in terms of that system of reference.

Of course, in terms of the Earth's inertial reference system you emitted the pulse at a forward angle, not perpendicular to the axis of your rocket, and the pulse will continue in that non-perpendicular direction in terms of that system of reference. Likewise the pulse will move in a straight line at whatever angle it was emitted in terms of any specified inertial reference system, and it will move at speed c in terms of each of those systems.

Note that this is a different question than you asked originally. You began by describing a ship that is undergoing constant proper acceleration of 1G, and you were asking about the curving of light paths in terms of an accelerating reference system, related to the curving of paths in a gravitational field. Now you have discarded the acceleration, and are purely talking about special relativity in flat spacetime.

> or will it move at a right angle to the point where the photon was emitted?

That phrase doesn't make sense, because a pulse of light is emitted from an event (time and place), and there is no absolute rest frame to enable you to identify spatial points at different times. For example, suppose you emit the pulse of light when you are passing a several space beacons in various states of motion that all coincided with your rocket at the time of the emission. Thereafter, which of those beacons do you regard at "the point where the photon was emitted"? It would have to be the beacon that is at absolute rest, but there is no such thing. So you can't talk meaningfully about "the [spatial] point where the pulse was emitted" at any time after the emission.

> The answer seems obvious: The photon will move away from the point
> where it was emitted, not away from me.

No, that's not correct. In general, the pulse will not be moving in a direction perpendicular to the ship's axis in any system of reference other than that of the ship itself, given that you emitted it perpendicularly in terms of that system of reference.

> And it doesn’t make any difference if I emit the photon while accelerating
> or while coasting.

That too is incorrect. If you are accelerating, then your co-moving system of inertial reference is constantly changing, and the pulse will follow a curved path in terms of your co-moving system of coordinates (which is necessarily limited, since it is accelerating).

On Wednesday, March 30, 2022 at 9:33:16 AM UTC-7, det...@outlook.com wrote:
> Using different frames of reference will just give different answers.
It is called "relativity", stubborn imbecile.