New Perspectives on Einstein's E = Mc2
SKU: 34447413475

New Perspectives on Einstein's E = Mc2

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New Perspectives on Einstein's E = Mc2Einstein's energy momentum relation is applicable to particles of all speeds, including the particle at rest and the massless particle moving with the speed of light. If one formula or formalism is applicable to all speeds, we say it is "Lorentz covariant." As for the internal space time symmetries, there does not appear to be a clear way to approach this problem. For a particle at rest, there are three spin degrees of freedom. For a massless

Einstein's energy-momentum relation is applicable to particles of all speeds, including the particle at rest and the massless particle moving with the speed of light. If one formula or formalism is applicable to all speeds, we say it is "Lorentz-covariant." As for the internal space-time symmetries, there does not appear to be a clear way to approach this problem. For a particle at rest, there are three spin degrees of freedom. For a massless particle, there are helicity and gauge degrees of freedom. The aim of this book is to present one Lorentz-covariant picture of these two different space-time symmetries. Using the same mathematical tool, it is possible to give a Lorentz-covariant picture of Gell-Mann's quark model for the proton at rest and Feynman's parton model for the fast-moving proton. The mathematical formalism for these aspects of the Lorentz covariance is based on two-by-two matrices and harmonic oscillators which serve as two basic scientific languages for many different branches of physics. It is pointed out that the formalism presented in this book is applicable to various aspects of optical sciences of current interest.

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SKU: 34447413475

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jin
Whiting, US
★★★★★ 5
Most comfortable pillow I’ve ever slept on
Size: Queen (1 Count), Color: Crescent White(cooling)
This is the most comfortable pillow I have ever slept on. It doesn't mash down like other pillows. Cradles my neck perfectly plus it’s cool. I broke my neck a couple of years ago and this pillow feels very good and comfortable. Definitely recommend to everyone. Ive used it since May and it’s retained its shape.
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Reviewed in the United States on June 6, 2026
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Verified Purchase
AreTrue
Belleville, US
★★★★★ 4
Smell
Size: Queen (2 Count), Color: Original White (Cooling)
The fact that there are not more comments on the smell of these pillows has me worried about some of yall. Listen, I LOVE the weight, and the firmness, it’s perfect for that. However, these pillows are RANK. They have a very strong mildew-ish smell that lingers. I took the outer cover off and washed it and let the pillow air out for a few days, the smell is still very strong when you press your face against it, which one does because it is in fact designed for that purpose. It smells so bad. It’s nauseating. I can smell it through two pillowcases and blanket that I threw on top of them hoping an extra layer would trap the smell. I’ll bake them in the Texas sun tomorrow and hope that helps, because otherwise these are the perfect pillows for someone who wants to feel like they are hugging a torso but can’t stand the sound/feel of someone else breathing. I don’t know…4 stars, if the smell goes away I’ll come back. Update: many many days later. Either they don’t really smell anymore or I got use to it. They’ve held their firmness and shape well. I like them.
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Reviewed in the United States on March 9, 2026
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Verified Purchase
Samantha
Birmingham, US
★★★★★ 5
Actually Cooling Pillow
Size: Queen (1 Count), Color: Original White (Cooling)
This is a really nice pillow, I was worried it would be too soft or too firm but it's just right and it's actually cooling, it feels cool every time I touch it. I've noticed an improvement in sleep since using it. Would recommend!
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Reviewed in the United States on May 27, 2026
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Tyler and Kaela
Port Orchard, US
★★★★★ 5
Repurchased in King Size – Still Love These Cooling Pillows
Size: King (2 Count), Color: Original White (Cooling), Size: King (2 Count), Color: Original White (Cooling)
After using the queen-size version of these pillows for over a year, we purchased the king-size set when we upgraded to a king mattress. Both my husband and I really like them. The cooling feature works well, and we like that each side feels different—when I run cold, I use the softer bamboo side, while my husband prefers the cooler side since he tends to sleep hot. They fit well in our king-size pillowcases and feel supportive in all sleeping positions, whether I’m on my stomach, side, or back. I also appreciate that you can remove some of the filling to adjust the firmness. The covers are washable, which makes them easy to maintain. Overall, we’re very happy with this repurchase and the long-lasting comfort.
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Reviewed in the United States on April 15, 2026
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Mystery Fan
Los Angeles, US
★★★★★ 3
Not great at cooling
Size: Queen (2 Count), Color: Original White (Cooling)
Each pillow cover has 2 sides, one marked for cooling, and the other a different fabric. The cooling side is about the same effectiveness as having a silk or satin pillow cover. It's only cool when you first touch it. The cooling side doesn't seem to absorb or wick moisture, so if you are sweaty - it keeps the moisture in place. You'll definitely want a regular pillow case over the pillow cover. In fact, if you suffer from night sweats, the non-cooling side is actually more comfortable. The pillow fill is ample, and simple to squish around for more support for your neck, etc. Think bean bag. But it will retain your impression after use. I find I need to do as I did when I had down pillows - give it a few good shakes in the morning when I make the bed to get it evened out for the coming night. In all, it is a well-made and comfortable pillow to sleep on, but it does not excel in cooling.
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Reviewed in the United States on May 29, 2026

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