Go Back   Physics Help Forum > College/University Physics Help > Special and General Relativity

Special and General Relativity Special and General Relativity Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Nov 13th 2015, 01:01 AM   #1
Member
 
Join Date: Jul 2013
Posts: 63
Example relativity

When E=m*c^2
1) Root(c^2)=c=Root(E/m)
2) 3*c*Root(c^2)=3*c*Root(E/m)=3*c^2

From 1) to 2) as an example,
As velocity is faster, mass is increased.
It means when velocity is increased, sec(time) is slower, and m(distance) is increased.
philipishin is offline   Reply With Quote
Old Nov 13th 2015, 10:51 AM   #2
Forum Admin
 
topsquark's Avatar
 
Join Date: Apr 2008
Location: On the dance floor, baby!
Posts: 2,857
Originally Posted by philipishin View Post
When E=m*c^2
1) Root(c^2)=c=Root(E/m)
2) 3*c*Root(c^2)=3*c*Root(E/m)=3*c^2

From 1) to 2) as an example,
As velocity is faster, mass is increased.
It means when velocity is increased, sec(time) is slower, and m(distance) is increased.
Most current interpretations of Relativity is that the momentum of the particle increases, but not the mass. The Mathematics are the same but the interpretation seems to me to be more comfortable. The (spatial) momentum component in the direction of travel is p = (gamma) mv. Since m can't change we can interpret it as the "rest mass" of the object. (There is also a convention to write m as m_0 but I think this is unnecessary notation.)

What are you doing in 2)? I don't see why you multiplied by 3c?

-Dan
__________________
Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup.

See the forum rules here.
topsquark is offline   Reply With Quote
Old Dec 1st 2015, 06:31 PM   #3
Pmb
Physics Team
 
Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,576
Originally Posted by topsquark
Most current interpretations of Relativity is that the momentum of the particle increases, but not the mass.
In my very humble opinion I contend that this not the best way to state your position. First of all nobody has ever counted who uses what. It's simply impossible to do and it would be unwise as well. And you cannot make any assumptions about what a person is thinking or what thought processes got him to a logical point based solely on what they've written. I know this as a fact. Also the usefulness of relativistic mass and invariant mass is dependent on which field is being studied at the moment.

I myself have decided never to try to tell people how to think but merely to tell them the physics of what they're dealing with.
Pmb is offline   Reply With Quote
Old Dec 1st 2015, 06:38 PM   #4
Pmb
Physics Team
 
Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,576
Originally Posted by philipishin
When E=m*c^2
1) Root(c^2)=c=Root(E/m)
2) 3*c*Root(c^2)=3*c*Root(E/m)=3*c^2

From 1) to 2) as an example,
As velocity is faster, mass is increased.
It means when velocity is increased, sec(time) is slower, and m(distance) is increased.
What exactly is the point that you're trying to make here? In 1) and 2) you're merely playing with algebra. The rest is independent of that and comes from special relativity.

But time does not slow down because of it. Time as measured in the frame in which he mass increases neither increases nor decreases.
Pmb is offline   Reply With Quote
Old Dec 1st 2015, 06:48 PM   #5
Forum Admin
 
topsquark's Avatar
 
Join Date: Apr 2008
Location: On the dance floor, baby!
Posts: 2,857
Originally Posted by Pmb View Post
In my very humble opinion I contend that this not the best way to state your position. First of all nobody has ever counted who uses what. It's simply impossible to do and it would be unwise as well. And you cannot make any assumptions about what a person is thinking or what thought processes got him to a logical point based solely on what they've written. I know this as a fact. Also the usefulness of relativistic mass and invariant mass is dependent on which field is being studied at the moment.

I myself have decided never to try to tell people how to think but merely to tell them the physics of what they're dealing with.
Point in fact this is the way I was taught, at least beyond casual comments in High School. I'm not trying to tell people what to think I'm merely telling them what the standard convention is. (At least to the best of my knowledge.)

-Dan

Edit: Okay, I'm looking at this from the POV of a particle Physicist. Perhaps a Relativist would describe things differently.
__________________
Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup.

See the forum rules here.

Last edited by topsquark; Dec 1st 2015 at 08:25 PM.
topsquark is offline   Reply With Quote
Old Dec 5th 2015, 01:48 AM   #6
Pmb
Physics Team
 
Join Date: Apr 2009
Location: Boston's North Shore
Posts: 1,576
Originally Posted by topsquark View Post
Point in fact this is the way I was taught, at least beyond casual comments in High School. I'm not trying to tell people what to think I'm merely telling them what the standard convention is. (At least to the best of my knowledge.)

-Dan

Edit: Okay, I'm looking at this from the POV of a particle Physicist. Perhaps a Relativist would describe things differently.
But you have to think of it like this: There are various applications of relativity in which its more convenient to use proper mass. One of them is in particle physics. In applications such as cosmology and general relativity (when you're speaking of the active gravitational mass) then relativistic mass is more convenient to use and actually better. Also when one is learning relativity. If one has a very good teacher and wants to give the student a thorough education on the concept of mass then he should teach them all possible scenarios one can run into. Then the reason for the use of relativistic mass becomes very clear. But teachers just don't do that anymore. They just don't want to spend time teaching tensors in SR. They leave that to their GR class. But when they get to their GR class they learn about the stress-energy-momentum tensor, which describes completely the mass of an object, but they don't teach about mass because they assume you learned everything you need to know in your SR class.

There just aren't teachers who know about all the possible scenarios that mass has to cover.

But in the end, the number of particle physicists dominate the relativity community. Therefore the use of proper mass dominates relativity. That's how people view what the standard convention is. They never learn why its like that. It in no way means that it's better to use it all around. That's why Alan Guth did that video for me on this. It's also why he makes a point to place it in his lecture notes for his Early Universe course. These lecture notes will eventually be made into a text. You read my website and article on this subject, didn't you?
Pmb is offline   Reply With Quote
Reply

  Physics Help Forum > College/University Physics Help > Special and General Relativity

Tags
relativity



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Relativity problem isaac Special and General Relativity 1 Apr 7th 2014 01:11 AM
Gravitation relativity philipishin Special and General Relativity 7 Sep 30th 2013 04:39 AM
Relativity Question? muon321 Special and General Relativity 1 Jun 18th 2013 05:26 AM
Relativity omkar13 Special and General Relativity 1 Dec 26th 2008 05:01 AM
special relativity evabern Special and General Relativity 2 Oct 6th 2008 04:26 AM


Facebook Twitter Google+ RSS Feed