About 50 years ago, Sarachick and Schappert [Phys. Rev. D. 1, 2738-2752(1970] showed that relativistic Thomson scattering leads to wavelength shifts that are proportional to the laser intensity. About 28 years later Chen et al. [Nature 396, 653-655 (1998)] used these shifts to estimate their laser intensity near 10 18 W/cm 2 . More recently there have been several theoretical studies aimed at exploiting nonlinear Thomson scattering as a tool for direct measurement of intensities well into the relativistic regime. We present the first quantitative study of this approach for intensities between 10 18 and 10 19 W/cm 2 . We show that the spectral shifts are in reasonable agreement with estimates of the peak intensity extracted from images of the focal area obtained at reduced power. Finally, we discuss the viability of the approach, its range of usefulness and how it might be extended to gauge intensities well in excess of 10 19 W/cm 2 .

In this paper we will show that photon–photon collision experiments using extreme lasers can provide measurable effects giving fundamental information about the essence of QED, its Lagrangian. A possible scenario with two counterpropagating ultra-intense lasers for an experiment to detect scattering between optical photons is analyzed. We discuss the importance of the pulse widths and waists, the best scenario for overlapping the beams and signal detection, as well as ways to distinguish the signal from the noise. This would need a high-precision measurement, with control of temporal jitter and noise. We conclude that such experiment is barely feasible at 1023 W cm−2 and very promising at 1024 W cm−2.

With a mix of prose, critical reflection, and an accompanying series of drawings inside a daily planner, this intimate essay reimagines multiple conceptions of "space" in relation to different kinds of sickness and wellbeing. Meditating on COVID-19 quarantine spaces and bipolar disorder mood/mind-spaces allowed me to discover messied "third" spaces that explore margins, and complicate ideas of boundaries and binaries. Doing so allowed me to think through new possibilities of healing, restoration, and intimacy when we talk about mental health. I offer up my personal account of a young female Asian American graduate student navigating a ten-year struggle with clinical bipolar disorder, and the personal experiences of "madness," relapse, and recovery during the winter and spring of 2021. I reflect on my daily routines inside my 800-square-foot apartment and my growing realization that prevailing ideas of "space" are incomplete and contradictory—but can be replete with futurities and learning possibilities. Fittingly, this creative piece does not endeavor to offer any neatly packaged analysis or solid conclusions. Instead, I present one account of grappling with mental illness under extraordinary circumstances and hope it can speak to individual and collective discussions on mental health, disability, and spatiality.