Ernst Mach, who was one of the eminent physicists, considered the atoms of matter to be a mental concept and sensation of mind as the only reality. He wrote, "Atoms cannot be perceived by the senses. Like all substances, they are things of the thought (and) a mathematical model for facilitating the mental reproduction of the facts."[1] Thus, behind Mach's view lies the doctrine that nothing can count as real or existent except an element of sensation.[2]
French scientist Poincare is also one of the staunch supporters of Idealism. He believed it impossible that anything can exist without the mind. He writes, "Does the harmony which human intelligence thinks it discovers in Nature exist apart from such intelligence? Assuredly no. A reality completely independent of the spirit that conceives it, sees it or feels it, is an impossibility. A world so external as that, even if it existed, would be for ever inaccessible to us. What we call 'objective reality' is, strictly speaking, that which is common to several thinking beings and might be common to all this common part, we shall see,can only be the harmony expressed by mathematical laws."[1] This shows clearly that Poincare was an idealist.