What is the meaning of this generic equation in String Theory?

  • Thread starter ZeroZero2
  • Start date
In summary, the conversation discusses an equation found in an article about string theory. The original poster is looking for an explanation of what the equation means. Some users point out that the equation has typos and uses a mix of different notation. The equation is attributed to Michio Kaku and is described as a Lagrangian for a quantum field with a quartic self-interaction. However, it is noted that the equation is quite generic and could represent many different possibilities.
  • #1
ZeroZero2
28
0
what is this equation??

I remember an article on String Theory on either Popular Science or Scientific America, and it had this equation:

attachment.php?attachmentid=25592&stc=1&d=1272997753.png


I no longer have the article and would like to know what this equation means.

Thanks!
 

Attachments

  • Screen shot 2010-05-04 at 1.26.05 PM.png
    Screen shot 2010-05-04 at 1.26.05 PM.png
    2.5 KB · Views: 731
Physics news on Phys.org
  • #2


no one knows? :uhh:


not a history of it, just what it represents...
like how E=mc[tex]^{2}[/tex] means energy is equal to mass multiplied by the speed of light squared.
 
  • #3


It looks like a lagrangian miss-spelled...

g<psi^dagger | psi >^2

it should read
 
  • #4


ansgar said:
It looks like a lagrangian miss-spelled...

g<psi^dagger | psi >^2

it should read

I don't think so...

I copied it directly from the magazine (I have the actual clipping of the equation).
 
Last edited:
  • #5
Found it!
It's Michio Kaku's equation and it describes strings in 10 dimensions

It was on Discover magazine

attachment.php?attachmentid=25601&stc=1&d=1273046597.jpg


http://discovermagazine.com/2005/aug/cover/article_view?b_start:int=3"
 

Attachments

  • string-math.jpg
    string-math.jpg
    6.6 KB · Views: 562
Last edited by a moderator:
  • #6


sorry but that equation is crap
 
  • #7


ansgar said:
sorry but that equation is crap

haha.. troll
 
  • #8


imean they are mixing bra-ket and wavefunction notation, you don't usally write <psi^dagger| since <psi| is the dual correspondence to |psi> ..
 
  • #9


ansgar said:
imean they are mixing bra-ket and wavefunction notation, you don't usally write <psi^dagger| since <psi| is the dual correspondence to |psi> ..
Actually that's right... maybe the magazine mistranscribed it or something. (Unless this is some sort of weird notation unique to string theory, but I have my doubts... I've studied some string theory and never come across that sort of notation)
 
  • #10


That equation is using a lot off different equations and comparing them. The derivative of i with respect to a certain time interval and the it, obviously, has the wave function Psi which is the derivative of uppercase gamma and I am pretty sure the g is reffering to gravity or some kind of force acting on it. H could be planks constant or like an angular momentum symbol. The i may be an imaginary number which could change the whole format of the equation. As far as L it could be length or momentum or something. The guy who discovered that equation must have done something wrong otherwise we would have heard of it before and there would be no doubts the string theory exists. But there are multiple string theories and not just one so it could pretain to a certain one we haven't heard of before. It could also be saying that when the strings collide and when that happens it creates a force, tourque, which is tau in that equation and it creates angular momentum and they are using it to find the length or shape of the string. Torque is frsin theta so idk there is many ways one could think of it. I really don't know the one Kaku is reffering to though.
 
  • #11


The equation has some typos and mixes different kinds of notation...I would write it

[tex]L = \psi^\dagger (i\partial_t - H) \psi + g(\psi^\dagger \psi)^2[/tex]

Unfortunately, it's hard to guess what Kaku could possibly mean by this, because this is actually something quite generic: It is just the Lagrangian for a quantum field [itex]\psi[/itex] with a quartic self-interaction. H is the Hamiltonian, and g is a coupling constant.

It is completely unspecified what sort of background spacetime the field Psi lives in, or what representations of what groups Psi might carry. This expression could really mean almost anything.

Note: Practically everything in bradley613's post above is complete nonsense.
 

1. What is the purpose of using equations in science?

Equations are used in science to describe and explain relationships between different variables or quantities. They allow us to make precise calculations and predictions about the physical world.

2. How do I interpret an equation in a scientific context?

To interpret an equation in a scientific context, it is important to understand the meaning of each variable and how they are related. Additionally, paying attention to the units of measurement used in the equation can provide important information about the physical phenomenon being described.

3. Can an equation have multiple meanings?

Yes, an equation can have multiple meanings depending on the context in which it is used. For example, the equation E=mc2 has different meanings in the fields of physics and chemistry.

4. How can I use equations to solve scientific problems?

Equations can be used to solve scientific problems by plugging in known values for the variables and solving for the unknown variable. It is important to understand the properties and rules of the equations being used in order to correctly solve the problem.

5. What happens if I don't understand an equation in my scientific research?

If you encounter an equation that you do not understand in your scientific research, it is important to consult with a knowledgeable colleague or do further research to fully understand it. It is important to have a complete understanding of the equations used in your research in order to accurately interpret and communicate your findings.

Similar threads

  • Beyond the Standard Models
Replies
26
Views
494
Replies
47
Views
4K
  • Beyond the Standard Models
Replies
31
Views
2K
  • Beyond the Standard Models
Replies
3
Views
1K
  • Beyond the Standard Models
Replies
13
Views
1K
Replies
30
Views
5K
Replies
2
Views
1K
  • Beyond the Standard Models
Replies
9
Views
2K
  • Beyond the Standard Models
Replies
28
Views
2K
Replies
2
Views
1K
Back
Top