Who's familiar with the conversion? - "In 15 years' ship-time they could reach Andromeda

@layman,

Between the two (the earth and the rocket which is under constant acceleration) which one is really moving? Don't say both are right. Which one is right when they claim the "other guy" is moving?

1 Reply

@layman,

Are you asking this because you want to get a better understanding of the science? Or are you asking this to justify your refusal to accept that the science is valid?

I could explain the science to you, but if you are just trying to argue against science, then I would just be wasting my time since you aren't going to accept it anyway.

This has ceased to be interesting or fun for me. If anyone wants to understand the science, I can help (up to the point of my education in science).

1 Reply

@maxdancona,

Quote:

Are you asking this because you want to get a better understanding of the science?

I'm asking for the purpose of trying to get a direct, sensible answer to simple questions, Max. I'm not looking for long strings of unsupported and irrelevant assertions.

So far, as an example, you have said that:

(1) both are correct when claiming the other guy is the one moving (which is non-sensical, for reasons I've fully explained) AND

(2) made a vague reference to the twin paradox and special relativity's "prediction." That prediction says only ONE of the two is moving, i.e., only ONE is "really" aging slower, even though both think it's the other guy.

They contradict each other. One makes sense, one doesn't.

1 Reply

@layman,

You insist that basic high school Physics in wrong. When I try to give you the correct explanation, as understood by any smart high school student, you just brush it off.

If you are not going to accept the answers because you believe that Physics is wrong, why should I keep giving them to you?

You either accept science... or you don't. If you aren't willing to accept the correct answers according to science, then it isn't worth me trying to explain to you what is believed by Physicists and taught in University Physics courses, is it.

If you don't accept the answers given by science (as practiced by physicists) then fine... but what's the point of continuing this discussion?

Maybe you are smarter than the people who have Science degrees and are now discovering planets, building new airplanes and sending robots to Mars. Who knows.

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@maxdancona,

The fact that something doesn't make sense to you, doesn't mean that it doesn't make sense.

I believe that if you took the time to understand it, rather than just rejecting every explanation you are given, you might be able to see why it really does make sense. You seem to be so set that you are right, and that science is wrong, that you aren't even willing to try to understand.

I could try to explain it again to you. Do you really think this is worth the time since you have already decided it doesn't make sense to you?

1 Reply

@maxdancona,

Quote:

You insist that basic high school Physics in wrong

I've never made any such claim, Max.

The suggestion here is that a spaceship can REALLY (not just mathematically) go 13.7 billion light years in just 23 years WITHOUT exceeding the speed of light. That should seem non-sensical to anyone who reads it. Reference to math tables won't answer the questions it raises. It is the APPLICATION of that math which is extremely suspect, to say the least.

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@maxdancona,

The question was this:

Quote:

Between the two (the earth and the rocket which is under constant acceleration) which one is really moving? Don't say both are right. Which one is right when they claim the "other guy" is moving?

Have an answer?

And I only mean as between the two of them. Obviously both of them are moving in one way or another (the earth is moving while orbiting the sun, for example). Which one speeded up?

1 Reply

@layman,

In high school physics students learn about Galilean relativity. This is far more basic than Special relativity. Galilean relativity is called that because it was understood by Galileo in the 1500s and all Physicists since.

In Galilean relativity person A in one inertial frame of reference can say that he is motionless and person B is moving. Person B can say that he is motionless in one inertial frame and that person A is moving.

Both people are correct in their frames of reference, and both frames of reference are equally valid.

This was understood for centuries before Einstein discovered Special relativity.

You are rejecting basic high school physics...

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@maxdancona,

Again... I will ask you. Are you interested in learning this so that you can understand it? Or are you going to keep just rejecting out of hand because it doesn't make sense to you? You can understand this... it just takes a little effort.

If you aren't going to make the effort to learn the science, then this isn't worth either of our time.

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@maxdancona,

Quote:

In Galilean relativity person A in one inertial frame of reference can say that he is motionless and person B is moving. Person B can say that he is motionless in one inertial frame and that person A is moving.

Sure they "can say" that. But both can't be right.

I can calculate the next solar eclipse by assuming the earth is absolutely motionless and the sun and all planets revolve around it. So what? Does that mean that the sun REALLY revolves around the earth? I mean, like, the math works, dammit.

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@maxdancona,

Quote:

Both people are correct in their frames of reference, and both frames of reference are equally valid.

Yeah, "in their frames of reference." That does NOT mean "in the real world."

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@layman,

I am not going to waste my time if you are not interested in learning how scientists view this. There is a correct answer... you aren't the first person to ask these questions (most of them were answered in the 1500s). You are having trouble with Galileo and Newton.

You have to make the effort to understand the science.

Are you interested in learning the correct science answer for this question (as taught in science courses in high school and college)?

If not, then you can believe whatever makes sense to you. And this discussion is a waste of my time and yours.

1 Reply

@maxdancona,

Quote:

You are having trouble with Galileo and Newton.

Heh, ya think? You're the one who has no clue about what Galileo said about what "valid" means, in the context you're using it. He certainly did NOT say that both A and B would be "right." In fact he denied it. As did Newton.

YOU don't understand the true meaning and implications of Newtonian relativity, I'm afraid.

1 Reply

@layman,

Ok. Just keep thinking what makes sense to you. Let's not waste any more time.

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@layman,

Quote:

I can calculate the next solar eclipse by assuming the earth is absolutely motionless and the sun and all planets revolve around it. So what? Does that mean that the sun REALLY revolves around the earth? I mean, like, the math works, dammit.

I can do the same calculations and get the same answer if I assume everything in the solar system revolve around the moon, or Mars, or Jupiter, or a point 100 feet away from Jupiter or...

Any of an infinite number of "points." They are all "equally valid" for purposes of predicting an eclipse. Are they all also equally TRUE (reflective of objective reality), ya think? Hmmmmmm?

Newsflash Max: Math aint "reality."

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@maxdancona,

If I'm going down the road at 60 mph, and I want to measure the difference between my speed and that of the road, I will get the same answer whether I assume:

1. That the road is not moving, but I am OR
2. That I am not moving, but the road is.

Both are "equally valid" if all I'm trying to determine is an absolute difference in speed.

But that doesn't mean that either proposition is "equally (likely to be) true."

Even LESS does it mean that BOTH are true (i.e., that BOTH my car AND the road are not moving). There could be no speed difference if that were true.

Just one of many things you seem incapable of understanding. I would withdraw from the discussion if I were you too, and if I only wanted to pontificate, rather than understand, or God forbid, answer questions if I spoke nonsense.

1 Reply

@layman,

By the way, Max, I hope you don't think I'm trying to make you "look foolish." You're doing that all on your own.

I'm just pointing out that you are saying foolish things. I wish there was no call for that.

1 Reply

@layman,

Quote:

I hope you don't think I'm trying to make you "look foolish." You're doing that all on your own

I love irony.

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@maxdancona,

maxdancona wrote:

I just want to point out that the basic point that someone in a spaceship travelling at near C will experience less time going to the nearest star than someone on Earth watching is not theoretical.

Lorentz contraction has been demonstrated by experiment, both by particles (see https://en.wikipedia.org/wiki/Time_dilation_of_moving_particles) and by experiments with Atomic clocks.

This is something that we have shown really happens.

Yeah, it is fairly clear.

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@oristarA,

Quote:

Yeah, it is fairly clear.

Indeed it is, Oris, as I said a long time back. Of course that does not enable it to exceed the speed of light.

Time does slow down for the MOVING OBJECT. Now, if the moving object says (as SR requires), that time for it has not slowed down, but rather that time on earth has slowed down, then that "object" is just plain wrong.

In order to make that claim, the people on the ship have to (erroneously) say that they are not the moving clock. They are at rest (or so they think, when making that claim). Of course, if they claim (as they are required to by SR), that they are "at rest," then needless to say they can't possibly be exceeding the speed of light (in their "frame of reference") no matter how fast they are going, because they are not moving at all.

See the point, Oris?

0 Replies

Who's familiar with the conversion? - "In 15 years' ship-time they could reach Andromeda

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