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The offsets between the radial velocities of the rotational transitions ofcarbon monoxide and the fine structure transitions of neutral and singlyionized carbon are used to test the hypothetical variation of the finestructure constant, alpha. From the analysis of the [CI] and [CII] finestructure lines and low J rotational lines of 12CO and 13CO, emitted by thedark cloud L1599B in the Milky Way disk, we find no evidence for fractionalchanges in alpha at the level of |$\Delta \alpha/\alpha$| < 3*10^-7. For theneighbour galaxy M33 a stringent limit on Delta alpha/alpha is set fromobservations of three HII zones in [CII] and CO emission lines: |$\Delta\alpha/\alpha$| < 4*10^-7. Five systems over the redshift interval z = 5.7-6.4,showing CO J=6-5, J=7-6 and [CII] emission, yield a limit on |$\Delta\alpha/\alpha$| < 1.3*10^-5. Thus, a combination of the [CI], [CII], and COemission lines turns out to be a powerful tool for probing the stability of thefundamental physical constants over a wide range of redshifts not accessible tooptical spectral measurements.

[CI], [CII] and CO emission lines as a probe for alpha variations at low and high redshifts