Quotes About Invariance

Symmetry principles are principles governing the laws of nature that say those laws look the same if you change your point of view in certain ways.

All objects moved through space-time at the exact same rate.

Relativity asserts that all observers, whatever their velocities relative to one another, measure exactly the same number for the speed of light. The invariance of the speed of light allows two apparently unrelated quantities, the dimension of time and the three dimensions of space, to be united into one four-dimensional entity, spacetime.

Never make a calculation until you know the answer. Make an estimate before every calculation, try a simple physical argument (symmetry! invariance! conservation!) before every derivation, guess the answer to every paradox and puzzle. Courage: No one else needs to know what the guess is. Therefore make it quickly, by instinct. A right guess reinforces this instinct. A wrong guess brings the refreshment of surprise. In either case life as a spacetime expert, however long, is more fun!

The three discrete invariances - reflection invariance, charge conjugation invariance, and time reversal invariance - are connected by an important theorem called the CPT theorem.

37. If you've seen the present, then you've seen everything -- as it's been since the beginning, as it will be forever. The same substance, the same form. All of it.

I don't think human beings have changed in 2,000 years.

Mathematics takes us into the region of absolute necessity, to which not only the actual word, but every possible word, must conform.

Symmetry does mean something different for physicists than for members of the public. It means that an object or a theory does not change when you make some transformation - either rotating or moving it or doing something to the equations.

In reality, time doesn't pass; we pass. Time itself is invariant. It just is. Therefore, past and future aren't separate locations, the way New York and Paris are separate locations. And since the past isn't a location, you can't travel to it.

Thus, they are free to replace some objects by others so long as the relations remain unchanged.

The general laws of nature are to be expressed by equations that hold true for all systems of coordinates, that is they are covariant with respect to any substitutions whatever.

the problem is then to develop a theory of invariance with respect to arbitrary linear transformations, in which, however, in contra-distinction to the case of affine geometry, we have a definite invariant quadratic form, viz. the metrical groundform once and for all as an absolute datum.

And an equation is the same whether it's written in red or green ink

I don't think I've changed since I was a little kid.

Einstein argued that the laws of Nature should appear to be the same for all observers in the Universe, no matter where they were or how they were moving. If they were not then there would exist privileged observers for whom the laws of Nature looked simpler than they did for other observers.

Einstein enunciated what he called the Principle of Covariance: that laws of Nature should be expressed in a form that will look the same for all observers, no matter where they are located and no matter how they are moving.

j'ai pris conscience que ce qui est en mouvement – en dépit de ses dangers – sera toujours meilleur que ce qui est immobile, et que le changement sera toujours quelque chose de plus noble que l'invariance ; car ce qui stagne est voué inévitablement à la dégénérescence, à la décomposition et, en fin de compte, au néant, alors que tout ce qui évolue saura durer, et même éternellement.