Sign in to follow this  
snick

Do objects move faster when you move towards them?

Recommended Posts

Posted (edited)

Hey guys, this may sound stupid but I am quite new to theoretical physics and I want to learn more. So, my question is, do objects move faster when you move towards them, for example at the speed of light? If you, for instance, move towards Andromeda at the speed of light, which is around 2.5 million light years away from us, for 100 years(just theoretically), Andromeda will be 2 499 900 light years away from us. That means the light from Andromeda will reach you faster than at the Earth. Does not that mean that while moving it should be rotating faster from your perspective, for example?

Edited by snick

Share this post


Link to post
Share on other sites

By what you would visually see, then yes, you would see events occurring faster at Andromeda.

Though you couldn't actually travel at the speed of light, just close to it.

The equation for this relationship is

fo = fs sqrt((1+v/c)/(1-v/c))

Where fo is the observed frequency, fs is the source frequency, and c is the speed of light.

Note that if you make v=c then you end up with fo = fs sqrt(2)/0)

And the division by 0 is undefined. ( but since travel at the speed of light is not allowed, this never arises.)

However, just because you are seeing events unfold more quickly at Andromeda, does not mean that you would conclude that they were unfolding faster.  Once you account for the effect caused by the decreasing distance between you and Andromeda, you would conclude that events were actually unfolding slower at Andromeda.

For example, if you were traveling at 0.99c, you would see events at Andromeda as happening 14 times faster, but would conclude that they were happening 7 times slower.

The 7 times slower would be due to time dilation, while the 14 times faster you see is due to Relativistic Doppler effect, which is a combination of time dilation and the effect caused by the decreasing distance.

Even this is only a part of the whole picture.  In order to understand what happens over the whole trip from Earth to Andromeda according to both Earth and ship would involve delving more deeply into Special Relativity.

 

 

 

Share this post


Link to post
Share on other sites
On ‎10‎/‎3‎/‎2018 at 12:32 PM, Janus said:

By what you would visually see, then yes, you would see events occurring faster at Andromeda.

Though you couldn't actually travel at the speed of light, just close to it.

The equation for this relationship is

fo = fs sqrt((1+v/c)/(1-v/c))

Where fo is the observed frequency, fs is the source frequency, and c is the speed of light.

Note that if you make v=c then you end up with fo = fs sqrt(2)/0)

And the division by 0 is undefined. ( but since travel at the speed of light is not allowed, this never arises.)

However, just because you are seeing events unfold more quickly at Andromeda, does not mean that you would conclude that they were unfolding faster.  Once you account for the effect caused by the decreasing distance between you and Andromeda, you would conclude that events were actually unfolding slower at Andromeda.

For example, if you were traveling at 0.99c, you would see events at Andromeda as happening 14 times faster, but would conclude that they were happening 7 times slower.

The 7 times slower would be due to time dilation, while the 14 times faster you see is due to Relativistic Doppler effect, which is a combination of time dilation and the effect caused by the decreasing distance.

Even this is only a part of the whole picture.  In order to understand what happens over the whole trip from Earth to Andromeda according to both Earth and ship would involve delving more deeply into Special Relativity.

 

 

 

Could the speed of light be exceeded if the gravitational forces generated could be counteracted, in theory that is?

Share this post


Link to post
Share on other sites
14 minutes ago, Menan said:

Could the speed of light be exceeded if the gravitational forces generated could be counteracted, in theory that is?

Nothing can exceed the speed of light.

And what gravitational forces are you referring to?

Share this post


Link to post
Share on other sites
1 hour ago, Menan said:

Could the speed of light be exceeded if the gravitational forces generated could be counteracted, in theory that is?

Like Strange, I'm at a bit of a loss by what you mean by "gravitational forces generated".

Share this post


Link to post
Share on other sites
45 minutes ago, Janus said:

Like Strange, I'm at a bit of a loss by what you mean by "gravitational forces generated".

I could be wrong, but as speed increases g forces and weight increase.  I would assume that this continues all the way up the speed ladder.  If gravity could be counteracted upon, would not the g forces and weight not accumulate up the speed ladder, making for no increase in power needs at or near light speed.  Einstein just made observations, what if he tried to build something???????????????????????

Share this post


Link to post
Share on other sites
9 minutes ago, Menan said:

I could be wrong, but as speed increases g forces and weight increase. 

As speed increases the energy of the object increases. Energy and mass are equivalent so this increase in energy can be described as an increase in mass (called “relativistic mass”). Most people avoid using relativistic mass because it causes exactly this sort of confusion. 

12 minutes ago, Menan said:

If gravity could be counteracted

We cannot counteract gravity

Share this post


Link to post
Share on other sites

Janus claritatis magister est. 

(That had had me puzzled for years,although  I have it mostly learned  for a good while now....the Doppler vs the time dilation,to mangle it a bit)

 

Share this post


Link to post
Share on other sites
21 hours ago, Strange said:

As speed increases the energy of the object increases. Energy and mass are equivalent so this increase in energy can be described as an increase in mass (called “relativistic mass”). Most people avoid using relativistic mass because it causes exactly this sort of confusion. 

We cannot counteract gravity

Not so long ago we couldn't fly or go to space either.  In fact not so long ago the Earth was not a planet and space did not yet exist.  The odd thing is that some people are so ready to blabber about the big bang, black holes, offer proof that the speed of light can not be surpassed by anything in the universe when effectively exactly zero percent of the universe has been explored.  Fact, everything in theoretical physics is as proven as bigfoot. 

Share this post


Link to post
Share on other sites
2 minutes ago, Menan said:

Not so long ago we couldn't fly or go to space either.

True. Obviously, I was only referring to what we currently know. I can’t see into the future. 

3 minutes ago, Menan said:

Fact, everything in theoretical physics is as proven as bigfoot. 

Nonsense. 

Share this post


Link to post
Share on other sites
18 minutes ago, Strange said:

True. Obviously, I was only referring to what we currently know. I can’t see into the future. 

Nonsense. 

Nothing in theoretical physics is proved, if it were it would not be theory.  Bigfoot is a theory, one that I do not put much faith in.  That said that the universe was a static bubble (theory) until Hubble created another theory based on more significant evidence then Einstein offered.  Now there are physicist theorizing that the universe is really a computer simulation.

Moral, get laid, because you are never going to know where the universe came from or where it's going.  Someone might someday, but college professors have no clue, nor do they have the ability to teach any fact on this topic

Share this post


Link to post
Share on other sites
30 minutes ago, Menan said:

Nothing in theoretical physics is proved, if it were it would not be theory.  Bigfoot is a theory, one that I do not put much faith in.  That said that the universe was a static bubble (theory) until Hubble created another theory based on more significant evidence then Einstein offered.  Now there are physicist theorizing that the universe is really a computer simulation.

You are confusing theory with hypothesis and I think the nonsense that you speak comes from that confusion. A theory (for example General Relativity) is something that has been proven experimentally, something that has been tested and works. A hypothesis is something that has not been proven (Bigfoot)
You also need to understand that things can be added to a theory - for example we already know that Einsteins General Relativity is not a complete picture of reality but its not wrong, in fact we are sure it is right because it has been tested endless times and always works. Bigfoot hasn't been tested nor proven.

Quote

Moral, get laid, because you are never going to know where the universe came from or where it's going.  


I can agree as to the possibility that we might never understand the Universe in its fullness, its certainly possible that we are not evolved enough or the Universe is an endless onion-like layer of abstractions which we will never fully unfold.

 

Quote

Someone might someday, but college professors have no clue, nor do they have the ability to teach any fact on this topic

That's complete nonsense. You can't undermine the whole concept of science because it just works. You know - computers work, airplanes fly, etc. 

Edited by koti

Share this post


Link to post
Share on other sites
20 minutes ago, Menan said:

Nothing in theoretical physics is proved

Correct. That is the nature of science. Nothing is proved. Everything is subject to change. 

20 minutes ago, Menan said:

if it were it would not be theory. 

Not sure what that means. “Theory” is the best it gets in science. 

21 minutes ago, Menan said:

Bigfoot is a theory, one that I do not put much faith in. 

It is a hypothesis with little credible evidence (and solid theoretical arguments against). Definitely not a theory. 

23 minutes ago, Menan said:

That said that the universe was a static bubble (theory) until Hubble created another theory based on more significant evidence then Einstein offered

Originally, the universe was thought to be static and infinite (Newton) based on the best evidence available. 

When more evidence became available the hypothesis of an expanding universe was confirmed and became a theory (currently the only viable theory of cosmology). 

That is the good thing about science, it adapts to fit the evidence. 

26 minutes ago, Menan said:

Now there are physicist theorizing that the universe is really a computer simulation.

Not a theory. Not even a hypothesis (because it is not based on evidence and is inherently untestable and therefore unscientific). 

27 minutes ago, Menan said:

Someone might someday, but college professors have no clue, nor do they have the ability to teach any fact on this topic

The “facts” that they teach is the evidence we have. They also teach past and current theories, and any hypotheses and speculations that might be relevant. 

You seem to be confusing “not knowing everything” with “knowing nothing”. Rookie mistake. Hopefully you won’t do it again. 

Share this post


Link to post
Share on other sites
46 minutes ago, koti said:

You are confusing theory with hypothesis and I think the nonsense that you speak comes from that confusion. A theory (for example General Relativity) is something that has been proven experimentally, something that has been tested and works. A hypothesis is something that has not been proven (Bigfoot)
You also need to understand that things can be added to a theory - for example we already know that Einsteins General Relativity is not a complete picture of reality but its not wrong, in fact we are sure it is right because it has been tested endless times and always works. Bigfoot hasn't been tested nor proven.


I can agree as to the possibility that we might never understand the Universe in its fullness, its certainly possible that we are not evolved enough or the Universe is an endless onion-like layer of abstractions which we will never fully unfold.

 

That's complete nonsense. You can't undermine the whole concept of science because it just works. You know - computers work, airplanes fly, etc. 

General Relativity from what I have read in several places, is a body of work that is not typically fully understood by more than 3 living people in the world at a time.  That said I am not one of those people, but every college kid in a physics class claims to understand this fully and puts Einstein up on a God pedestal.  I am going to say this and it is based on fundamental logic, which is claiming to have proof mathematical or otherwise (the math dictates that 85 percent of the universe is missing)(it's not missing, we just do not know what the universe is) that nothing can travel faster then light, without having knowledge of everything in the universe is an unprovable hypothesis or theory.  We all have the same percentage access to all knowable knowledge of the universe which might be expressed as 1 trillionth, of 1 trillionth, of 1 trillionth of a single percent.  Claiming that nothing can exceed light speed requires knowledge that we just do not possess. 

Note I do not reject any of theoretical physics, I just keep it in perspective

42 minutes ago, Strange said:

Correct. That is the nature of science. Nothing is proved. Everything is subject to change. 

Not sure what that means. “Theory” is the best it gets in science. 

It is a hypothesis with little credible evidence (and solid theoretical arguments against). Definitely not a theory. 

Originally, the universe was thought to be static and infinite (Newton) based on the best evidence available. 

When more evidence became available the hypothesis of an expanding universe was confirmed and became a theory (currently the only viable theory of cosmology). 

That is the good thing about science, it adapts to fit the evidence. 

Not a theory. Not even a hypothesis (because it is not based on evidence and is inherently untestable and therefore unscientific). 

The “facts” that they teach is the evidence we have. They also teach past and current theories, and any hypotheses and speculations that might be relevant. 

You seem to be confusing “not knowing everything” with “knowing nothing”. Rookie mistake. Hopefully you won’t do it again. 

Theory is not the best it gets in science. Physics is basically the study of everything, many if not most things are clear cut and proved.  People get mixed up and believe that theoretical physics is the main body of science.  It's not, in fact it only exist to explain what we really do not know

Share this post


Link to post
Share on other sites
1 minute ago, Menan said:

General Relativity from what I have read in several places, is a body of work that is not typically fully understood by more than 3 living people in the world at a time.

Nonsense. Thousands of postgraduate students (and even a few dedicated amateurs) understand it. 

And it is not accepted because “Einstein is on a pedestal” but because of the evidence. 

Share this post


Link to post
Share on other sites
8 minutes ago, Strange said:

Nonsense. Thousands of postgraduate students (and even a few dedicated amateurs) understand it. 

And it is not accepted because “Einstein is on a pedestal” but because of the evidence. 

I can't find my first source of this as I read it years ago, at a time when many of you were not yet eggs and sperm yet, but here is another source for the three persons list

https://www.physicsforums.com/threads/only-three-people-understand-general-relativity.935624/

Note the people who truly comprehend the entire work should all in theory be able to add to it and have those additions verified.  All people try to do is either prove or disprove it. 

Share this post


Link to post
Share on other sites
39 minutes ago, Menan said:

General Relativity from what I have read in several places, is a body of work that is not typically fully understood by more than 3 living people in the world at a time.  That said I am not one of those people, but every college kid in a physics class claims to understand this fully and puts Einstein up on a God pedestal.  I am going to say this and it is based on fundamental logic, which is claiming to have proof mathematical or otherwise (the math dictates that 85 percent of the universe is missing)(it's not missing, we just do not know what the universe is) that nothing can travel faster then light, without having knowledge of everything in the universe is an unprovable hypothesis or theory.  We all have the same percentage access to all knowable knowledge of the universe which might be expressed as 1 trillionth, of 1 trillionth, of 1 trillionth of a single percent.  Claiming that nothing can exceed light speed requires knowledge that we just do not possess. 

Note I do not reject any of theoretical physics, I just keep it in perspective

Theory is not the best it gets in science. Physics is basically the study of everything, many if not most things are clear cut and proved.  People get mixed up and believe that theoretical physics is the main body of science.  It's not, in fact it only exist to explain what we really do not know

There are some very complex implications of Relativity which are difficult to grasp because of the counterintuitive nature of spacetime. Humans do not posses the mental tools to understand these things automatically the same way that we understand that a thrown rock will fall somewhere in front of you. This doesn't mean that you can't study Relativity on your own level...light speed cannot be exceeded (or even achieved) by a massive object because mass/energy would become infinite if that happened -> its not possible to achieve infinite energy to propell something massive to light speed.  There is a retired NASA engineer in this very thread who understands Relativity in its fullness, there is another guy who builds atomic clocks for the military, he understands ReIativity in its fullness as well. Instead of asserting nonsense you could ask questions, it really does work better that way. And it really does not get any better in science than a Scientific Theory. You can't just barge into a science forum straight into the Relativity section and undermine physics and the whole concept of science, that's just completely crazy don't you think? Especially that the device youre using to type your posts here depends entirely on scientific theories - nothing more. It is clear to everyone reading that you are missing knowledge on Relativity (like most of us), why don't you ask questions, I assure you many smart people will take time to give you answers. Just shoot.

 

Edited by koti

Share this post


Link to post
Share on other sites
35 minutes ago, koti said:

There are some very complex implications of Relativity which are difficult to grasp because of the counterintuitive nature of spacetime. Humans do not posses the mental tools to understand these things automatically the same way that we understand that a thrown rock will fall somewhere in front of you. This doesn't mean that you can't study Relativity on your own level...light speed cannot be exceeded (or even achieved) by a massive object because mass/energy would become infinite if that happened -> its not possible to achieve infinite energy to propell something massive to light speed.  There is a retired NASA engineer in this very thread who understands Relativity in its fullness, there is another guy who builds atomic clocks for the military, he understands ReIativity in its fullness as well. Instead of asserting nonsense you could ask questions, it really does work better that way. And it really does not get any better in science than a Scientific Theory. You can't just barge into a science forum straight into the Relativity section and undermine physics and the whole concept of science, that's just completely crazy don't you think? Especially that the device youre using to type your posts here depends entirely on scientific theories - nothing more. It is clear to everyone reading that you are missing knowledge on Relativity (like most of us), why don't you ask questions, I assure you many smart people will take time to give you answers. Just shoot.

 

Thanks everyone, but I am a little flustered right now, my son just came home after joining the Navy with top secret military clearance and will be in the computer field on subs.

So perhaps I will solve the weight problem at light speed tomorrow. (somebody will someday, or we die here)(Hawking)

Thanks to everyone!

Share this post


Link to post
Share on other sites
10 minutes ago, Menan said:

 

So perhaps I will solve the weight problem at light speed tomorrow. (somebody will someday, or we die here)(Hawking)

Thanks to everyone!

Remember that weight and mass are two different properties. 

Mass

Weight

Share this post


Link to post
Share on other sites
29 minutes ago, koti said:

Remember that weight and mass are two different properties. 

Mass

Weight

But if you could remove by some means the weight of a mass, the amount of energy needed to move the mass would be reduced or eliminated and light speed might be possible. 

Laugh, but once Von Braun was laughed at by the brightest minds for proposing that it should be possible to shoot an object to the moon. He hadn't built squat yet, minus the bicycle with fireworks attached that is.

We achieve faster than light speed, or die here

 

How I know that no one really understands relativity.  Because no one adds to it, or continues it in any way, its a dead field, like studying history, it can't change, real science is an unstoppable forward march and is not missing 85 percent of the equation

 

50 minutes ago, koti said:

Remember that weight and mass are two different properties. 

Mass

Weight

If mass increases at light speed, why.  Would atoms get bigger? or increase in number.

 

?

Share this post


Link to post
Share on other sites
8 hours ago, Menan said:

I can't find my first source of this as I read it years ago, at a time when many of you were not yet eggs and sperm yet, but here is another source for the three persons list

 

It was a joke made 100 years ago. It wasn’t true then and certainly isn’t true now. It is taught in every university. It is used in many areas of science and technology. 

6 hours ago, Menan said:

How I know that no one really understands relativity.  Because no one adds to it, or continues it in any way, its a dead field, like studying history, it can't change, real science is an unstoppable forward march and is not missing 85 percent of the equation

What!? It is constantly being studied and developed. One of the challenges is understanding more complex situations where GR applies. There are only analytical solutions for a few simple cases like symmetrical spheres in an empty universe (which is a good enough approximation for many real world applications). Another area of work is understanding the relationship between GR and quantum theory. There has been (and continues to be) a lot of new ideas coming from that - from Hawking radiation to ideas to explain dark matter or dark energy. 

It is relativity (and evidence) that tells us that 85% is unknown!

6 hours ago, Menan said:

If mass increases at light speed, why.  Would atoms get bigger? or increase in number.

LRelativistic mass is just a measure of increased energy (mass and energy are related, remember: e=mc2). A lot of people say the concept should not be used because it causes too much confusion (as in your question). 

Edited by Strange

Share this post


Link to post
Share on other sites
6 hours ago, Menan said:

But if you could remove by some means the weight of a mass, the amount of energy needed to move the mass would be reduced or eliminated and light speed might be possible.

 

 

Can you think of any circumstances where the weight is removed? 

Tip 1 - it is very much possible.

Tip 2 - the amount of energy needed to push a mass to a certain velocity when the weight is „removed” is the same.

Please take the time to read throught the wikipedia descriptions of mass and weight I posted. 

Share this post


Link to post
Share on other sites
7 hours ago, Menan said:

But if you could remove by some means the weight of a mass, the amount of energy needed to move the mass would be reduced or eliminated and light speed might be possible. 

If you could remove the mass, then the object would move at light speed. However, mass appears to be a fundamental property of things so there certainly isn't any way, currently, to remove mass without destroying the object in the process - e.g. turning it into photons.

But, of course, being able to manipulate mass and inertia is a fundamental trope in SF.

Share this post


Link to post
Share on other sites
1 hour ago, Strange said:

If you could remove the mass, then the object would move at light speed. However, mass appears to be a fundamental property of things so there certainly isn't any way, currently, to remove mass without destroying the object in the process - e.g. turning it into photons.

But, of course, being able to manipulate mass and inertia is a fundamental trope in SF.

Was there a way to the moon before the way was created?

 

Again creation is not an option, we create a way off, or die here. (adapted from Hawking)

Edited by Menan

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this