# The Naked Scientists Forum

### Author Topic: Does gravity vary with temperature?  (Read 33073 times)

#### Steve Wiles

• Guest
##### Does gravity vary with temperature?
« on: 13/01/2009 09:02:54 »
Steve Wiles asked the Naked Scientists:
Does gravity between 2 objects vary dependent on the heat of the two objects?
What do you think?

#### syhprum

• Neilep Level Member
• Posts: 3770
• Thanked: 15 times
##### Does gravity vary with temperature?
« Reply #1 on: 13/01/2009 11:30:59 »
gravitational force is proportional to the mass of the bodies involved.
The mass of a body consists of its rest mass and a relativic component due to the energy it possess M=E/c^2.
This is a tiny amount at everday temperatures and is probably undetectable

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #2 on: 13/01/2009 11:38:29 »
gravitational force is proportional to the mass of the bodies involved.
The mass of a body consists of its rest mass and a relativic component due to the energy it possess M=E/c^2.
This is a tiny amount at everday temperatures and is probably undetectable
If the body it's at rest, it's all (rest) mass = mass and this increases with temperature.

#### syhprum

• Neilep Level Member
• Posts: 3770
• Thanked: 15 times
##### Does gravity vary with temperature?
« Reply #3 on: 13/01/2009 13:08:46 »
The point I was rather ineffectively trying to make was although mass and energy are both affected by gravity how small the effect is in every day situations.
I calculate that heating one liter of water from 0°C to 100°C will increase its effective mass by .00464 nanograms.

A more interesting case arises when we look at the mass of Baryons although in this case the forces involved are strong nuclear mediated by Gluons

http://www.nature.com/news/2008/081120/full/news.2008.1246.html

PS this is a very interesting article now only available to members, if any kind soul could email me a copy I would be very grateful
« Last Edit: 13/01/2009 19:15:34 by syhprum »

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #4 on: 13/01/2009 15:27:06 »
The answer is yes gravity varies inversely with temperature the colder a galaxy the larger the gravitational force it will eventually implode.

#### yor_on

• Naked Science Forum GOD!
• Posts: 11652
• (Ah, yes:) *a table is always good to hide under*
##### Does gravity vary with temperature?
« Reply #5 on: 13/01/2009 19:24:53 »
When you heat up something you transfer energy to it, that energy can be seen as mass.
(Ah, I do have some views here, but I will keep quiet:)

On the other hand most (all?) matter will expand when heat is added.
That means that the density, and mass, of the object will become smaller smaller per unit volume.

But the answer is a definite yes.
Any which way:)
« Last Edit: 13/01/2009 19:28:16 by yor_on »

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #6 on: 13/01/2009 23:01:57 »
The answer is yes gravity varies inversely with temperature the colder a galaxy the larger the gravitational force it will eventually implode.

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Does gravity vary with temperature?
« Reply #7 on: 13/01/2009 23:05:38 »
The answer to the original question is no.  Gravity does not in any way depend on temperature.
« Last Edit: 14/01/2009 09:14:54 by Soul Surfer »

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #8 on: 13/01/2009 23:21:47 »
To lightarrow HUH if you don't understand my reply wouldn't it have been easier to say that you dont know where I am going with this one.

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #9 on: 14/01/2009 18:32:40 »
To lightarrow HUH if you don't understand my reply wouldn't it have been easier to say that you dont know where I am going with this one.
No, you are not even starting, because what you say is wrong.

#### Bikerman

• Sr. Member
• Posts: 119
##### Does gravity vary with temperature?
« Reply #10 on: 14/01/2009 19:14:50 »
How can a cold object possible have a higher gravitational 'field' than a hot one? That makes no sense to me. We know that gravity is proportional to mass. We know that mass increases as you add energy (although I agree the amount is very tiny indeed), and the corrolory is that it decreases with less energy. That means that a hot object has more mass than a cold one and the corollary of that is that a hot object has a higher gravity than a cold one (albeit so tiny that it would probably be undetectable)....
« Last Edit: 14/01/2009 19:18:17 by Bikerman »

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #11 on: 15/01/2009 01:28:46 »
We know that gravity is proportional to g (the gravitational constant) and the square of the masses but there are problems with the maths we now have dark matter which corrects the problem but we still don't know what it is, lets hope Stephen comes up with an answer.

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #12 on: 15/01/2009 15:58:40 »
Did the Maths again gravity is invesely proportioal to temperature.

g proportional to C/T

It was derived from the Curie_ Wiess Law.
g is the gravitational constant, C is the Curie constant and T the absolute temperatue.

A Davis B.Sc.  15th January 2009.

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #13 on: 15/01/2009 18:02:29 »
Did the Maths again gravity is invesely proportioal to temperature.

g proportional to C/T

It was derived from the Curie_ Wiess Law.
g is the gravitational constant, C is the Curie constant and T the absolute temperatue.

A Davis B.Sc.  15th January 2009.

You mean "magnetic susceptibility" not "gravitational constant":
http://en.wikipedia.org/wiki/Curie-Weiss_law

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #14 on: 16/01/2009 17:04:57 »
You are correct but I have used another equation to convert magnetic susceptibility to g. Not shown.

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #15 on: 16/01/2009 18:01:24 »
You are correct but I have used another equation to convert magnetic susceptibility to g. Not shown.
Ok, but it would be science fiction...

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #16 on: 17/01/2009 00:21:56 »
I worked out the equation but forgot to test it numericaly in order to see if it had a significant effect. Been doing that today. So assuming that a star has some Iron in it's core and that it's temperature is about three million degrees then mu,r is approximately one, now if the star cools down to 1100degK the Curie temp then mu,r is 5000 a very large change. I am saying that the gravity will change by this amount as well provided there is no significant change in its spin. A cold Galaxy will implode. I am reluctant to put the full equation in at this point in time, thinking  of setting up a Website.

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Does gravity vary with temperature?
« Reply #17 on: 17/01/2009 09:34:04 »
A Davis  what you are saying sounds like rubbish to me but if you want to explain it in more detail post it in the "new theories" area not here.  This is the place for well established scientific explanations.

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #18 on: 18/01/2009 23:57:39 »

Has Cambridge University solved J12 + 1/2

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Does gravity vary with temperature?
« Reply #19 on: 19/01/2009 09:16:25 »
That question is not clearly understandable without giving proper context and just looks like mystic rubbish to me.

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #20 on: 19/01/2009 15:59:49 »

Jn + 1/2 are half integer Bessel Functions and are used in the solution for the Proton. Has Cambridge University solved J12 + 1/2
« Last Edit: 19/01/2009 17:33:59 by A Davis »

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Does gravity vary with temperature?
« Reply #21 on: 19/01/2009 22:23:39 »
I now understand it a bit better.  Bessel functions are used for lots of things inculding analysing the harmonic series of bells but I still do not see the significance of the question. Bessel functions have been known for hundreds of years

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #22 on: 19/01/2009 23:45:15 »

Half integer bessel functions are different from ordinary bessel functions. They take into account that action at a distance is not possible it's given the word {retarded potential} it takes time to act. There was a programme on BBC4 about Stephen one of His young Students said that they were working on the 12th solution I understood what he meant. I am looking for someone with the same understanding on this site who has a link with Cambridge University and can answer the question, I apologise but I was testing you. I still need to know. Has Cambridge University
solved J12 + 1/2

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Does gravity vary with temperature?
« Reply #23 on: 20/01/2009 12:01:15 »

Half integer bessel functions are different from ordinary bessel functions. They take into account that action at a distance is not possible it's given the word {retarded potential} it takes time to act. There was a programme on BBC4 about Stephen one of His young Students said that they were working on the 12th solution I understood what he meant. I am looking for someone with the same understanding on this site who has a link with Cambridge University and can answer the question, I apologise but I was testing you. I still need to know. Has Cambridge University
solved J12 + 1/2
There is no need to look for "strange" mathematics. Try to solve:
y'(x) = log[x + y(x)];
y(0) = 1.

#### A Davis

• Sr. Member
• Posts: 106
##### Does gravity vary with temperature?
« Reply #24 on: 30/01/2009 01:59:53 »
I've put the equation you require on the new theory forum.

#### The Naked Scientists Forum

##### Does gravity vary with temperature?
« Reply #24 on: 30/01/2009 01:59:53 »